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Renske Penning, Adele McKinney, Joris C. Verster, Alcohol Hangover Symptoms and Their Contribution to the Overall Hangover Severity, Alcohol and Alcoholism, Volume 47, Issue 3, May/June 2012, Pages 248–252, https://doi.org/10.1093/alcalc/ags029
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Abstract
Aims: Scientific literature suggests a large number of symptoms that may be present the day after excessive alcohol consumption. The purpose of this study was to explore the presence and severity of hangover symptoms, and determine their interrelationship. Methods: A survey was conducted among n = 1410 Dutch students examining their drinking behavior and latest alcohol hangover. The severity of 47 presumed hangover symptoms were scored on a 10-point scale ranging from 0 (absent) to 10 (maximal). Factor analysis was conducted to summarize the data into groups of associated symptoms that contribute significantly to the alcohol hangover and symptoms that do not. Results: About half of the participants (56.1%, n = 791) reported having had a hangover during the past month. Most commonly reported and most severe hangover symptoms were fatigue (95.5%) and thirst (89.1%). Factor analysis revealed 11 factors that together account for 62% of variance. The most prominent factor ‘drowsiness’ (explained variance 28.8%) included symptoms such as drowsiness, fatigue, sleepiness and weakness. The second factor ‘cognitive problems’ (explained variance 5.9%) included symptoms such as reduced alertness, memory and concentration problems. Other factors, including the factor ‘disturbed water balance’ comprising frequently reported symptoms such as ‘dry mouth’ and ‘thirst’, contributed much less to the overall hangover (explained variance <5%). Conclusion: Drowsiness and impaired cognitive functioning are the two dominant features of alcohol hangover.
INTRODUCTION
The morning after a night of excessive drinking, many people wake up with a familiar but unpleasant feeling. The symptoms experienced during this post-intoxication state are caused by the alcohol hangover, which develops when blood alcohol concentrations return to zero (Verster et al., 2010). The feeling of general misery can persist up to 24 h and can significantly affect the planned activities and cognitive functioning (Stephens et al., 2008; Ling et al., 2010). While the majority of people are familiar with this phenomenon, ∼28% of drinkers report never having a hangover (Howland et al., 2008a,b). At present, no theoretical model accounts for the pathology of alcohol hangover (Penning et al., 2010). This lack of knowledge is reflected by our limited ability to accurately define the alcohol hangover, its vital symptoms and how they are interrelated. The lack of scientific interest in the pathology of alcohol hangover is remarkable, since its socioeconomic consequences are much higher when compared with various common diseases and health risk factors (Wiese et al., 2000; Lopez et al., 2006).
To increase our knowledge about the phenomenon of alcohol hangover, it is important to determine which symptoms are experienced during the hangover state, their severity and how these symptoms are interrelated.
Up to now, only a small number of studies has systematically examined the frequency and severity of (some) hangover symptoms (Slustke et al., 2003; Rohsenow et al., 2007; Howland et al., 2008a,b). Other studies experimentally induced hangovers and reviewed the effects on the human body. In a social environment, Chapman (1970) administered bourbon and vodka to induce hangovers in volunteers. Subjects were asked to report on 11 predetermined symptoms, i.e. thirst, fatigue, drowsiness, trouble sleeping, general malaise, dizziness, loss of appetite, nausea, headache, depression and anxiety. All symptoms were reported by one or more subjects, but their severity was not rated (Chapman, 1970). Ylikahri et al. (1974) also induced hangover in healthy volunteers. Subjects rated a number of predetermined symptoms, and an overall hangover severity score was computed. The authors reported that nausea, fatigue, thirst and tension correlated best with the overall hangover severity (Ylikahri et al., 1974). Rohsenow et al. (2007) combined the symptoms mentioned in the studies of Chapman and Ylikhari to compose a new list of symptoms, the Acute Hangover Scale. They induced hangover in marine cadets. Although all symptoms of the list were experienced, they differed in severity. Thirst scored the highest on severity, where heart racing was on average experienced as being the least severe.
In their review, Swift and Davidson (1998) distinguished eight groups of symptoms that were reported during alcohol hangover. The symptoms were categorized according to their assumed common biological relationship and include constitutional, pain, gastrointestinal, sleep and biological rhythms, sensory, cognitive, mood and sympathetic hyperactivity. On theoretical grounds, Swift and Davidson (1998) proposed that symptoms that are caused by the same mechanism are interrelated. Hence, tremor and sweating were categorized in the same category (i.e. symptoms caused by sympathetic hyperactivity) as cardiovascular effects. On first sight, this results in a plausible categorization. The categorization was however not derived from data.
Nevertheless, Slustke et al. (2003) selected the items for their hangover scale solely based on the symptoms mentioned by Swift and Davidson. Therefore, it is unsure if the Hangover Symptom Scale adequately reflects the core symptoms of the alcohol hangover. Also, a number of symptoms that have been listed by various researches (including Swift and Davidson, 1998; Slustke et al., 2003) are being criticized as representing states of withdrawal or acute alcohol intoxication effects (Verster et al., 2010). For example, trouble sleeping/insomnia should not be considered as a hangover symptom because it is experienced before the hangover occurs. Furthermore, the Acute Hangover Scale (Rohsenow et al., 2007) was based on the results of experimental studies, and was not designed, nor aimed to be comprehensive. It is therefore likely that it misses symptoms that should be assessed to conduct a comprehensive factor analysis.
An extensive literature search (including PubMed/Medline, Embase, Psychinfo and cross-references) yielded 47 presumed hangover symptoms. It was evident from the literature search that some of the symptoms seem to occur much more frequently than others (e.g. frequent reports of drowsiness versus rare symptoms such as suicidal thoughts). Also, the impact on daily activities differs significantly between symptoms (e.g. dry mouth has no significant impact on performance, while headache or dizziness can be very impairing). The purpose of the present survey was to explore the presence and severity of all alcohol hangover symptoms mentioned in the literature and determine how they are interrelated.
MATERIALS AND METHODS
Dutch students were approached on different locations of Utrecht University, and asked to complete a survey. The survey comprised questions about their drinking habits, and, if applicable, the symptoms they experienced during their latest hangover. Hangover symptoms included in this survey were chosen because they had been mentioned in the previous literature, experimental and survey studies that examined alcohol hangover. Participants rated the severity of 47 symptoms on a 10-point scale ranging from 0 (absent) to 10 (maximal).
Participants who agreed to take part, completed the survey on the location where they were approached, such as the campuses, colleges and the library. There was no recruitment rate recorded; however, the vast majority was willing to cooperate. Students were not compensated for their participation. The Institutional Review Board reviewed the protocol. No medical ethics committee approval was needed for conducting the anonymous survey.
Data from those subjects aged 18–30 were used for the statistical analyses. Statistical analyses were conducted with SPSS, version 19. Mean score and standard deviation (SD) was computed for each hangover symptom, and the sum of the 47 items was computed to generate an overall hangover score. A principal component factor analysis was conducted, applying an orthogonal rotation (Varimax with Kaizer Normalization) to check for interrelation between the items. Mean scores were computed for each factor and correlated with the overall hangover score. Cronbach's alpha was computed to establish the reliability of each factor.
RESULTS
A total of 1410 participants completed the questionnaire, of which 56.1% (n = 791, 31.3% men and 68.7% women) had experienced at least one hangover during the last month. Their mean (SD) age was 20.1 (2.1) years; on average, they consume 17.0 (14.8) alcoholic drinks per week and experience 2.5 (2.3) hangovers per month. There was a significant correlation between the number of alcoholic drinks consumed per week and number of hangovers experienced per month (r = 0.688, P = 0.0001). Data from these participants were included in the statistical analyses. The evening before their latest hangover they consumed 10.6 (5.9) alcoholic consumptions, followed by 6.4 (2.0) h of sleep. The frequency and severity of hangover symptoms experienced the following day are summarized in Table 1.
Symptom . | Reported (%) . | Mean (SD) score . |
---|---|---|
Fatigue (being tired) | 95.5 | 6.8 (2.3) |
Thirst | 89.1 | 6.4 (2.5) |
Drowsiness | 88.3 | 6.4 (2.4) |
Sleepiness | 87.7 | 6.4 (2.4) |
Headache | 87.2 | 5.8 (2.6) |
Dry mouth | 83.0 | 5.9 (2.6) |
Nausea | 81.4 | 5.8 (2.7) |
Weakness | 79.9 | 5.5 (2.5) |
Reduced alertness | 78.5 | 4.6 (2.4) |
Concentration problems | 77.6 | 5.0 (2.6) |
Apathy (lack of interest/concern) | 74.0 | 5.7 (2.6) |
Increased reaction time | 74.0 | 4.5 (2.4) |
Reduced appetite | 61.9 | 5.3 (2.8) |
Clumsiness | 51.4 | 4.3 (2.5) |
Agitation | 49.5 | 4.1 (2.3) |
Vertigo | 48.0 | 4.4 (2.6) |
Memory problems | 47.6 | 4.8 (2.6) |
Gastrointestinal complaints | 46.7 | 4.6 (2.6) |
Dizziness | 46.0 | 4.4 (2.6) |
Stomach pain | 44.7 | 4.2 (2.5) |
Tremor | 38.9 | 4.6 (2.6) |
Balance problems | 38.6 | 4.2 (2.5) |
Restlessness | 36.8 | 4.3 (2.6) |
Shivering | 34.4 | 4.3 (2.6) |
Sweating | 33.9 | 3.8 (2.3) |
Disorientation | 33.8 | 4.0 (2.4) |
Audio-sensitivity | 33.3 | 4.0 (2.3) |
Photo-sensitivity | 33.1 | 4.1 (2.4) |
Blunted affect | 29.9 | 4.1 (2.6) |
Muscle pain | 29.4 | 4.5 (2.6) |
Loss of taste | 28.0 | 3.8 (2.5) |
Regret | 27.1 | 4.4 (2.6) |
Confusion | 25.8 | 4.1 (2.6) |
Guilt | 25.2 | 4.1 (2.6) |
Gastritis | 23.4 | 4.2 (2.7) |
Impulsivity | 22.7 | 4.2 (2.5) |
Hot/cold flashes | 21.4 | 4.3 (2.4) |
Vomiting | 20.8 | 5.9 (3.2) |
Heart pounding | 19.4 | 3.9 (2.5) |
Depression | 18.9 | 3.7 (2.5) |
Palpitations | 17.0 | 4.0 (2.5) |
Tinnitus | 16.8 | 3.6 (2.2) |
Nystagmus | 16.1 | 3.8 (2.5) |
Anger | 10.1 | 3.4 (2.4) |
Respiratory problems | 9.7 | 3.2 (2.3) |
Anxiety | 7.4 | 3.2 (2.3) |
Suicidal thoughts | 1.8 | 4.7 (3.3) |
Symptom . | Reported (%) . | Mean (SD) score . |
---|---|---|
Fatigue (being tired) | 95.5 | 6.8 (2.3) |
Thirst | 89.1 | 6.4 (2.5) |
Drowsiness | 88.3 | 6.4 (2.4) |
Sleepiness | 87.7 | 6.4 (2.4) |
Headache | 87.2 | 5.8 (2.6) |
Dry mouth | 83.0 | 5.9 (2.6) |
Nausea | 81.4 | 5.8 (2.7) |
Weakness | 79.9 | 5.5 (2.5) |
Reduced alertness | 78.5 | 4.6 (2.4) |
Concentration problems | 77.6 | 5.0 (2.6) |
Apathy (lack of interest/concern) | 74.0 | 5.7 (2.6) |
Increased reaction time | 74.0 | 4.5 (2.4) |
Reduced appetite | 61.9 | 5.3 (2.8) |
Clumsiness | 51.4 | 4.3 (2.5) |
Agitation | 49.5 | 4.1 (2.3) |
Vertigo | 48.0 | 4.4 (2.6) |
Memory problems | 47.6 | 4.8 (2.6) |
Gastrointestinal complaints | 46.7 | 4.6 (2.6) |
Dizziness | 46.0 | 4.4 (2.6) |
Stomach pain | 44.7 | 4.2 (2.5) |
Tremor | 38.9 | 4.6 (2.6) |
Balance problems | 38.6 | 4.2 (2.5) |
Restlessness | 36.8 | 4.3 (2.6) |
Shivering | 34.4 | 4.3 (2.6) |
Sweating | 33.9 | 3.8 (2.3) |
Disorientation | 33.8 | 4.0 (2.4) |
Audio-sensitivity | 33.3 | 4.0 (2.3) |
Photo-sensitivity | 33.1 | 4.1 (2.4) |
Blunted affect | 29.9 | 4.1 (2.6) |
Muscle pain | 29.4 | 4.5 (2.6) |
Loss of taste | 28.0 | 3.8 (2.5) |
Regret | 27.1 | 4.4 (2.6) |
Confusion | 25.8 | 4.1 (2.6) |
Guilt | 25.2 | 4.1 (2.6) |
Gastritis | 23.4 | 4.2 (2.7) |
Impulsivity | 22.7 | 4.2 (2.5) |
Hot/cold flashes | 21.4 | 4.3 (2.4) |
Vomiting | 20.8 | 5.9 (3.2) |
Heart pounding | 19.4 | 3.9 (2.5) |
Depression | 18.9 | 3.7 (2.5) |
Palpitations | 17.0 | 4.0 (2.5) |
Tinnitus | 16.8 | 3.6 (2.2) |
Nystagmus | 16.1 | 3.8 (2.5) |
Anger | 10.1 | 3.4 (2.4) |
Respiratory problems | 9.7 | 3.2 (2.3) |
Anxiety | 7.4 | 3.2 (2.3) |
Suicidal thoughts | 1.8 | 4.7 (3.3) |
Severity was scored on a 10-point scale ranging from 0 (absent) to 10 (extreme).
Symptom . | Reported (%) . | Mean (SD) score . |
---|---|---|
Fatigue (being tired) | 95.5 | 6.8 (2.3) |
Thirst | 89.1 | 6.4 (2.5) |
Drowsiness | 88.3 | 6.4 (2.4) |
Sleepiness | 87.7 | 6.4 (2.4) |
Headache | 87.2 | 5.8 (2.6) |
Dry mouth | 83.0 | 5.9 (2.6) |
Nausea | 81.4 | 5.8 (2.7) |
Weakness | 79.9 | 5.5 (2.5) |
Reduced alertness | 78.5 | 4.6 (2.4) |
Concentration problems | 77.6 | 5.0 (2.6) |
Apathy (lack of interest/concern) | 74.0 | 5.7 (2.6) |
Increased reaction time | 74.0 | 4.5 (2.4) |
Reduced appetite | 61.9 | 5.3 (2.8) |
Clumsiness | 51.4 | 4.3 (2.5) |
Agitation | 49.5 | 4.1 (2.3) |
Vertigo | 48.0 | 4.4 (2.6) |
Memory problems | 47.6 | 4.8 (2.6) |
Gastrointestinal complaints | 46.7 | 4.6 (2.6) |
Dizziness | 46.0 | 4.4 (2.6) |
Stomach pain | 44.7 | 4.2 (2.5) |
Tremor | 38.9 | 4.6 (2.6) |
Balance problems | 38.6 | 4.2 (2.5) |
Restlessness | 36.8 | 4.3 (2.6) |
Shivering | 34.4 | 4.3 (2.6) |
Sweating | 33.9 | 3.8 (2.3) |
Disorientation | 33.8 | 4.0 (2.4) |
Audio-sensitivity | 33.3 | 4.0 (2.3) |
Photo-sensitivity | 33.1 | 4.1 (2.4) |
Blunted affect | 29.9 | 4.1 (2.6) |
Muscle pain | 29.4 | 4.5 (2.6) |
Loss of taste | 28.0 | 3.8 (2.5) |
Regret | 27.1 | 4.4 (2.6) |
Confusion | 25.8 | 4.1 (2.6) |
Guilt | 25.2 | 4.1 (2.6) |
Gastritis | 23.4 | 4.2 (2.7) |
Impulsivity | 22.7 | 4.2 (2.5) |
Hot/cold flashes | 21.4 | 4.3 (2.4) |
Vomiting | 20.8 | 5.9 (3.2) |
Heart pounding | 19.4 | 3.9 (2.5) |
Depression | 18.9 | 3.7 (2.5) |
Palpitations | 17.0 | 4.0 (2.5) |
Tinnitus | 16.8 | 3.6 (2.2) |
Nystagmus | 16.1 | 3.8 (2.5) |
Anger | 10.1 | 3.4 (2.4) |
Respiratory problems | 9.7 | 3.2 (2.3) |
Anxiety | 7.4 | 3.2 (2.3) |
Suicidal thoughts | 1.8 | 4.7 (3.3) |
Symptom . | Reported (%) . | Mean (SD) score . |
---|---|---|
Fatigue (being tired) | 95.5 | 6.8 (2.3) |
Thirst | 89.1 | 6.4 (2.5) |
Drowsiness | 88.3 | 6.4 (2.4) |
Sleepiness | 87.7 | 6.4 (2.4) |
Headache | 87.2 | 5.8 (2.6) |
Dry mouth | 83.0 | 5.9 (2.6) |
Nausea | 81.4 | 5.8 (2.7) |
Weakness | 79.9 | 5.5 (2.5) |
Reduced alertness | 78.5 | 4.6 (2.4) |
Concentration problems | 77.6 | 5.0 (2.6) |
Apathy (lack of interest/concern) | 74.0 | 5.7 (2.6) |
Increased reaction time | 74.0 | 4.5 (2.4) |
Reduced appetite | 61.9 | 5.3 (2.8) |
Clumsiness | 51.4 | 4.3 (2.5) |
Agitation | 49.5 | 4.1 (2.3) |
Vertigo | 48.0 | 4.4 (2.6) |
Memory problems | 47.6 | 4.8 (2.6) |
Gastrointestinal complaints | 46.7 | 4.6 (2.6) |
Dizziness | 46.0 | 4.4 (2.6) |
Stomach pain | 44.7 | 4.2 (2.5) |
Tremor | 38.9 | 4.6 (2.6) |
Balance problems | 38.6 | 4.2 (2.5) |
Restlessness | 36.8 | 4.3 (2.6) |
Shivering | 34.4 | 4.3 (2.6) |
Sweating | 33.9 | 3.8 (2.3) |
Disorientation | 33.8 | 4.0 (2.4) |
Audio-sensitivity | 33.3 | 4.0 (2.3) |
Photo-sensitivity | 33.1 | 4.1 (2.4) |
Blunted affect | 29.9 | 4.1 (2.6) |
Muscle pain | 29.4 | 4.5 (2.6) |
Loss of taste | 28.0 | 3.8 (2.5) |
Regret | 27.1 | 4.4 (2.6) |
Confusion | 25.8 | 4.1 (2.6) |
Guilt | 25.2 | 4.1 (2.6) |
Gastritis | 23.4 | 4.2 (2.7) |
Impulsivity | 22.7 | 4.2 (2.5) |
Hot/cold flashes | 21.4 | 4.3 (2.4) |
Vomiting | 20.8 | 5.9 (3.2) |
Heart pounding | 19.4 | 3.9 (2.5) |
Depression | 18.9 | 3.7 (2.5) |
Palpitations | 17.0 | 4.0 (2.5) |
Tinnitus | 16.8 | 3.6 (2.2) |
Nystagmus | 16.1 | 3.8 (2.5) |
Anger | 10.1 | 3.4 (2.4) |
Respiratory problems | 9.7 | 3.2 (2.3) |
Anxiety | 7.4 | 3.2 (2.3) |
Suicidal thoughts | 1.8 | 4.7 (3.3) |
Severity was scored on a 10-point scale ranging from 0 (absent) to 10 (extreme).
It is evident from Table 1 that most hangover symptoms that were mentioned in the literature are commonly experienced, but only about a quarter of these symptoms were reported by >75% of subjects. Also, the severity of most symptoms was mild-to-moderate, with mean scores <5 (out of 10). There was a small but significant relationship between the number of alcoholic drinks consumed the evening before the hangover day and the overall hangover severity (r = 0.25, P = 0.0001).
Factor analysis revealed 11 factors that together account for 62% of variance (R2). The factors and the loading of each symptom are summarized in Table 2.
. | Factor . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
. | 1 . | 2 . | 3 . | 4 . | 5 . | 6 . | 7 . | 8 . | 9 . | 10 . | 11 . |
Explained variance (%) | 28.8 | 5.9 | 4.5 | 4.1 | 3.5 | 3.0 | 2.7 | 2.5 | 2.5 | 2.3 | 2.2 |
Cumulative (%) | 28.8 | 34.6 | 39.1 | 43.2 | 46.7 | 47.7 | 52.4 | 54.9 | 57.4 | 59.7 | 62.0 |
Fatigue (being tired) | 0.834 | 0.163 | 0.075 | 0.091 | 0.075 | 0.091 | 0.081 | 0.057 | 0.019 | −0.017 | 0.016 |
Sleepiness | 0.798 | 0.160 | 0.081 | 0.085 | 0.082 | 0.108 | 0.081 | 0.083 | 0.007 | −0.013 | 0.069 |
Drowsiness | 0.727 | 0.273 | 0.112 | 0.057 | 0.049 | 0.090 | 0.089 | 0.042 | −0.006 | 0.074 | 0.066 |
Apathy (lack of interest/concern) | 0.623 | 0.186 | 0.152 | 0.181 | 0.051 | 0.074 | 0.036 | 0.243 | 0.082 | 0.118 | −0.102 |
Weakness | 0.511 | 0.343 | 0.257 | 0.156 | 0.178 | 0.152 | 0.051 | 0.008 | 0.197 | 0.146 | −0.023 |
Increased reaction time | 0.385 | 0.715 | 0.108 | 0.019 | 0.106 | 0.101 | 0.035 | 0.046 | 0.084 | 0.161 | 0.033 |
Reduced alertness | 0.448 | 0.703 | 0.095 | 0.035 | 0.104 | 0.080 | 0.050 | 0.042 | 0.094 | 0.123 | −0.004 |
Concentration problems | 0.465 | 0.624 | 0.121 | 0.056 | 0.060 | 0.060 | 0.055 | 0.111 | 0.099 | 0.112 | −0.125 |
Disorientation | 0.070 | 0.587 | 0.072 | 0.246 | 0.273 | 0.083 | 0.179 | 0.194 | −0.024 | 0.037 | 0.176 |
Memory problems | 0.174 | 0.572 | 0.132 | 0.126 | −0.017 | 0.096 | 0.147 | 0.285 | 0.272 | 0.049 | −0.114 |
Clumsiness | 0.197 | 0.572 | 0.279 | 0.031 | 0.446 | 0.077 | 0.032 | 0.194 | 0.084 | 0.077 | 0.052 |
Confusion | 0.050 | 0.559 | 0.112 | 0.354 | 0.092 | 0.113 | 0.214 | 0.171 | −0.023 | 0.016 | 0.118 |
Dry mouth | 0.412 | 0.093 | 0.606 | −0.053 | 0.070 | −0.009 | 0.039 | 0.086 | 0.252 | 0.098 | −0.051 |
Thirst | 0.456 | 0.098 | 0.583 | −0.056 | 0.135 | 0.021 | −0.007 | 0.083 | 0.248 | 0.131 | −0.003 |
Hot/cold flashes | 0.052 | 0.120 | 0.570 | 0.210 | 0.039 | 0.193 | 0.259 | 0.061 | −0.016 | 0.135 | −0.029 |
Shivering | 0.078 | 0.244 | 0.518 | 0.136 | 0.280 | 0.352 | 0.215 | −0.090 | 0.022 | 0.212 | −0.018 |
Tremor | 0.100 | 0.286 | 0.500 | 0.103 | 0.244 | 0.305 | 0.200 | −0.106 | 0.002 | 0.188 | −0.076 |
Sweating | 0.101 | 0.055 | 0.395 | 0.146 | 0.199 | 0.147 | 0.270 | 0.311 | 0.073 | 0.215 | 0.026 |
Muscle pain | 0.150 | 0.192 | 0.392 | 0.176 | 0.164 | 0.098 | 0.037 | 0.228 | 0.008 | −0.064 | 0.189 |
Nystagmus | 0.004 | 0.166 | 0.367 | 0.193 | 0.019 | 0.271 | 0.211 | 0.312 | −0.139 | 0.024 | 0.067 |
Anxiety | 0.074 | 0.086 | −0.037 | 0.711 | −0.064 | 0.106 | 0.188 | 0.028 | 0.131 | 0.141 | −0.104 |
Depression | 0.172 | 0.095 | 0.080 | 0.709 | 0.055 | 0.065 | 0.136 | 0.176 | 0.171 | 0.025 | −0.070 |
Anger | 0.008 | 0.108 | 0.134 | 0.657 | 0.178 | 0.106 | 0.012 | 0.103 | 0.075 | 0.087 | 0.244 |
Agitation | 0.317 | 0.138 | 0.279 | 0.453 | 0.248 | 0.021 | −0.032 | 0.065 | −0.038 | 0.100 | −0.074 |
Dizziness | 0.157 | 0.197 | 0.124 | 0.039 | 0.697 | 0.270 | 0.187 | 0.124 | 0.265 | 0.075 | −0.085 |
Vertigo | 0.176 | 0.260 | 0.110 | 0.003 | 0.685 | 0.257 | 0.161 | 0.099 | 0.262 | 0.128 | −0.053 |
Balance problems | 0.067 | 0.496 | 0.254 | 0.089 | 0.565 | 0.108 | 0.035 | 0.139 | 0.094 | 0.087 | 0.082 |
Tinnitus | 0.101 | 0.025 | 0.140 | 0.213 | 0.543 | −0.034 | 0.139 | 0.199 | −0.186 | 0.082 | 0.061 |
Stomach pain | 0.161 | 0.043 | 0.064 | 0.074 | 0.066 | 0.774 | 0.093 | 0.119 | 0.125 | 0.001 | 0.026 |
Gastrointestinal complaints | 0.153 | 0.120 | 0.243 | 0.098 | 0.060 | 0.676 | 0.072 | 0.194 | 0.106 | −0.110 | 0.017 |
Gastritis | 0.048 | 0.135 | 0.150 | 0.060 | 0.110 | 0.532 | 0.213 | −0.032 | 0.017 | 0.147 | 0.066 |
Nausea | 0.245 | 0.008 | −0.032 | 0.042 | 0.299 | 0.481 | −0.014 | 0.013 | 0.428 | 0.229 | −0.110 |
Heart pounding | 0.122 | 0.143 | 0.132 | 0.139 | 0.118 | 0.077 | 0.845 | 0.047 | 0.081 | 0.050 | −0.063 |
Palipitations | 0.092 | 0.173 | 0.100 | 0.095 | 0.099 | 0.171 | 0.844 | 0.021 | 0.033 | 0.080 | −0.020 |
Respiratory problems | 0.037 | 0.004 | 0.167 | 0.115 | 0.129 | 0.120 | 0.593 | 0.250 | 0.075 | 0.102 | 0.198 |
Loss of taste | 0.049 | 0.189 | 0.309 | −0.020 | 0.048 | 0.084 | 0.076 | 0.579 | 0.214 | 0.202 | −0.222 |
Impulsivity | 0.081 | 0.113 | −0.045 | 0.097 | 0.244 | 0.011 | 0.125 | 0.554 | 0.158 | 0.023 | 0.294 |
Restlessness | 0.267 | 0.203 | −0.008 | 0.228 | 0.180 | 0.217 | 0.034 | 0.553 | −0.019 | 0.060 | −0.059 |
Blunted affect | 0.175 | 0.334 | 0.093 | 0.277 | 0.112 | 0.011 | 0.083 | 0.495 | 0.019 | 0.092 | 0.038 |
Guilt | 0.084 | 0.158 | 0.185 | 0.336 | 0.032 | −0.005 | 0.159 | 0.216 | 0.651 | −0.154 | 0.199 |
Regret | 0.087 | 0.209 | 0.200 | 0.445 | 0.061 | 0.000 | 0.126 | 0.095 | 0.593 | −0.101 | 0.157 |
Vomiting | −0.022 | 0.067 | −0.023 | 0.074 | 0.132 | 0.380 | −0.001 | −0.018 | 0.586 | 0.095 | −0.043 |
Reduced appetite | 0.165 | 0.055 | 0.117 | −0.015 | 0.012 | 0.183 | 0.059 | 0.260 | 0.407 | 0.240 | −0.439 |
Audio-sensitivity | 0.068 | 0.235 | 0.170 | 0.098 | 0.037 | 0.068 | 0.115 | 0.152 | 0.021 | 0.748 | 0.091 |
Photo-sensitivity | 0.066 | 0.156 | 0.213 | 0.169 | 0.155 | −0.024 | 0.126 | 0.070 | 0.018 | 0.735 | 0.181 |
Headache | 0.416 | −0.052 | 0.003 | 0.014 | 0.122 | 0.112 | 0.009 | 0.031 | −0.011 | 0.451 | −0.053 |
Suicidal thoughts | 0.033 | 0.058 | 0.011 | 0.000 | −0.029 | 0.084 | 0.047 | 0.065 | 0.092 | 0.234 | 0.771 |
. | Factor . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
. | 1 . | 2 . | 3 . | 4 . | 5 . | 6 . | 7 . | 8 . | 9 . | 10 . | 11 . |
Explained variance (%) | 28.8 | 5.9 | 4.5 | 4.1 | 3.5 | 3.0 | 2.7 | 2.5 | 2.5 | 2.3 | 2.2 |
Cumulative (%) | 28.8 | 34.6 | 39.1 | 43.2 | 46.7 | 47.7 | 52.4 | 54.9 | 57.4 | 59.7 | 62.0 |
Fatigue (being tired) | 0.834 | 0.163 | 0.075 | 0.091 | 0.075 | 0.091 | 0.081 | 0.057 | 0.019 | −0.017 | 0.016 |
Sleepiness | 0.798 | 0.160 | 0.081 | 0.085 | 0.082 | 0.108 | 0.081 | 0.083 | 0.007 | −0.013 | 0.069 |
Drowsiness | 0.727 | 0.273 | 0.112 | 0.057 | 0.049 | 0.090 | 0.089 | 0.042 | −0.006 | 0.074 | 0.066 |
Apathy (lack of interest/concern) | 0.623 | 0.186 | 0.152 | 0.181 | 0.051 | 0.074 | 0.036 | 0.243 | 0.082 | 0.118 | −0.102 |
Weakness | 0.511 | 0.343 | 0.257 | 0.156 | 0.178 | 0.152 | 0.051 | 0.008 | 0.197 | 0.146 | −0.023 |
Increased reaction time | 0.385 | 0.715 | 0.108 | 0.019 | 0.106 | 0.101 | 0.035 | 0.046 | 0.084 | 0.161 | 0.033 |
Reduced alertness | 0.448 | 0.703 | 0.095 | 0.035 | 0.104 | 0.080 | 0.050 | 0.042 | 0.094 | 0.123 | −0.004 |
Concentration problems | 0.465 | 0.624 | 0.121 | 0.056 | 0.060 | 0.060 | 0.055 | 0.111 | 0.099 | 0.112 | −0.125 |
Disorientation | 0.070 | 0.587 | 0.072 | 0.246 | 0.273 | 0.083 | 0.179 | 0.194 | −0.024 | 0.037 | 0.176 |
Memory problems | 0.174 | 0.572 | 0.132 | 0.126 | −0.017 | 0.096 | 0.147 | 0.285 | 0.272 | 0.049 | −0.114 |
Clumsiness | 0.197 | 0.572 | 0.279 | 0.031 | 0.446 | 0.077 | 0.032 | 0.194 | 0.084 | 0.077 | 0.052 |
Confusion | 0.050 | 0.559 | 0.112 | 0.354 | 0.092 | 0.113 | 0.214 | 0.171 | −0.023 | 0.016 | 0.118 |
Dry mouth | 0.412 | 0.093 | 0.606 | −0.053 | 0.070 | −0.009 | 0.039 | 0.086 | 0.252 | 0.098 | −0.051 |
Thirst | 0.456 | 0.098 | 0.583 | −0.056 | 0.135 | 0.021 | −0.007 | 0.083 | 0.248 | 0.131 | −0.003 |
Hot/cold flashes | 0.052 | 0.120 | 0.570 | 0.210 | 0.039 | 0.193 | 0.259 | 0.061 | −0.016 | 0.135 | −0.029 |
Shivering | 0.078 | 0.244 | 0.518 | 0.136 | 0.280 | 0.352 | 0.215 | −0.090 | 0.022 | 0.212 | −0.018 |
Tremor | 0.100 | 0.286 | 0.500 | 0.103 | 0.244 | 0.305 | 0.200 | −0.106 | 0.002 | 0.188 | −0.076 |
Sweating | 0.101 | 0.055 | 0.395 | 0.146 | 0.199 | 0.147 | 0.270 | 0.311 | 0.073 | 0.215 | 0.026 |
Muscle pain | 0.150 | 0.192 | 0.392 | 0.176 | 0.164 | 0.098 | 0.037 | 0.228 | 0.008 | −0.064 | 0.189 |
Nystagmus | 0.004 | 0.166 | 0.367 | 0.193 | 0.019 | 0.271 | 0.211 | 0.312 | −0.139 | 0.024 | 0.067 |
Anxiety | 0.074 | 0.086 | −0.037 | 0.711 | −0.064 | 0.106 | 0.188 | 0.028 | 0.131 | 0.141 | −0.104 |
Depression | 0.172 | 0.095 | 0.080 | 0.709 | 0.055 | 0.065 | 0.136 | 0.176 | 0.171 | 0.025 | −0.070 |
Anger | 0.008 | 0.108 | 0.134 | 0.657 | 0.178 | 0.106 | 0.012 | 0.103 | 0.075 | 0.087 | 0.244 |
Agitation | 0.317 | 0.138 | 0.279 | 0.453 | 0.248 | 0.021 | −0.032 | 0.065 | −0.038 | 0.100 | −0.074 |
Dizziness | 0.157 | 0.197 | 0.124 | 0.039 | 0.697 | 0.270 | 0.187 | 0.124 | 0.265 | 0.075 | −0.085 |
Vertigo | 0.176 | 0.260 | 0.110 | 0.003 | 0.685 | 0.257 | 0.161 | 0.099 | 0.262 | 0.128 | −0.053 |
Balance problems | 0.067 | 0.496 | 0.254 | 0.089 | 0.565 | 0.108 | 0.035 | 0.139 | 0.094 | 0.087 | 0.082 |
Tinnitus | 0.101 | 0.025 | 0.140 | 0.213 | 0.543 | −0.034 | 0.139 | 0.199 | −0.186 | 0.082 | 0.061 |
Stomach pain | 0.161 | 0.043 | 0.064 | 0.074 | 0.066 | 0.774 | 0.093 | 0.119 | 0.125 | 0.001 | 0.026 |
Gastrointestinal complaints | 0.153 | 0.120 | 0.243 | 0.098 | 0.060 | 0.676 | 0.072 | 0.194 | 0.106 | −0.110 | 0.017 |
Gastritis | 0.048 | 0.135 | 0.150 | 0.060 | 0.110 | 0.532 | 0.213 | −0.032 | 0.017 | 0.147 | 0.066 |
Nausea | 0.245 | 0.008 | −0.032 | 0.042 | 0.299 | 0.481 | −0.014 | 0.013 | 0.428 | 0.229 | −0.110 |
Heart pounding | 0.122 | 0.143 | 0.132 | 0.139 | 0.118 | 0.077 | 0.845 | 0.047 | 0.081 | 0.050 | −0.063 |
Palipitations | 0.092 | 0.173 | 0.100 | 0.095 | 0.099 | 0.171 | 0.844 | 0.021 | 0.033 | 0.080 | −0.020 |
Respiratory problems | 0.037 | 0.004 | 0.167 | 0.115 | 0.129 | 0.120 | 0.593 | 0.250 | 0.075 | 0.102 | 0.198 |
Loss of taste | 0.049 | 0.189 | 0.309 | −0.020 | 0.048 | 0.084 | 0.076 | 0.579 | 0.214 | 0.202 | −0.222 |
Impulsivity | 0.081 | 0.113 | −0.045 | 0.097 | 0.244 | 0.011 | 0.125 | 0.554 | 0.158 | 0.023 | 0.294 |
Restlessness | 0.267 | 0.203 | −0.008 | 0.228 | 0.180 | 0.217 | 0.034 | 0.553 | −0.019 | 0.060 | −0.059 |
Blunted affect | 0.175 | 0.334 | 0.093 | 0.277 | 0.112 | 0.011 | 0.083 | 0.495 | 0.019 | 0.092 | 0.038 |
Guilt | 0.084 | 0.158 | 0.185 | 0.336 | 0.032 | −0.005 | 0.159 | 0.216 | 0.651 | −0.154 | 0.199 |
Regret | 0.087 | 0.209 | 0.200 | 0.445 | 0.061 | 0.000 | 0.126 | 0.095 | 0.593 | −0.101 | 0.157 |
Vomiting | −0.022 | 0.067 | −0.023 | 0.074 | 0.132 | 0.380 | −0.001 | −0.018 | 0.586 | 0.095 | −0.043 |
Reduced appetite | 0.165 | 0.055 | 0.117 | −0.015 | 0.012 | 0.183 | 0.059 | 0.260 | 0.407 | 0.240 | −0.439 |
Audio-sensitivity | 0.068 | 0.235 | 0.170 | 0.098 | 0.037 | 0.068 | 0.115 | 0.152 | 0.021 | 0.748 | 0.091 |
Photo-sensitivity | 0.066 | 0.156 | 0.213 | 0.169 | 0.155 | −0.024 | 0.126 | 0.070 | 0.018 | 0.735 | 0.181 |
Headache | 0.416 | −0.052 | 0.003 | 0.014 | 0.122 | 0.112 | 0.009 | 0.031 | −0.011 | 0.451 | −0.053 |
Suicidal thoughts | 0.033 | 0.058 | 0.011 | 0.000 | −0.029 | 0.084 | 0.047 | 0.065 | 0.092 | 0.234 | 0.771 |
Shaded bold printed factor loadings indicate the factor to which a symptom belongs.
. | Factor . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
. | 1 . | 2 . | 3 . | 4 . | 5 . | 6 . | 7 . | 8 . | 9 . | 10 . | 11 . |
Explained variance (%) | 28.8 | 5.9 | 4.5 | 4.1 | 3.5 | 3.0 | 2.7 | 2.5 | 2.5 | 2.3 | 2.2 |
Cumulative (%) | 28.8 | 34.6 | 39.1 | 43.2 | 46.7 | 47.7 | 52.4 | 54.9 | 57.4 | 59.7 | 62.0 |
Fatigue (being tired) | 0.834 | 0.163 | 0.075 | 0.091 | 0.075 | 0.091 | 0.081 | 0.057 | 0.019 | −0.017 | 0.016 |
Sleepiness | 0.798 | 0.160 | 0.081 | 0.085 | 0.082 | 0.108 | 0.081 | 0.083 | 0.007 | −0.013 | 0.069 |
Drowsiness | 0.727 | 0.273 | 0.112 | 0.057 | 0.049 | 0.090 | 0.089 | 0.042 | −0.006 | 0.074 | 0.066 |
Apathy (lack of interest/concern) | 0.623 | 0.186 | 0.152 | 0.181 | 0.051 | 0.074 | 0.036 | 0.243 | 0.082 | 0.118 | −0.102 |
Weakness | 0.511 | 0.343 | 0.257 | 0.156 | 0.178 | 0.152 | 0.051 | 0.008 | 0.197 | 0.146 | −0.023 |
Increased reaction time | 0.385 | 0.715 | 0.108 | 0.019 | 0.106 | 0.101 | 0.035 | 0.046 | 0.084 | 0.161 | 0.033 |
Reduced alertness | 0.448 | 0.703 | 0.095 | 0.035 | 0.104 | 0.080 | 0.050 | 0.042 | 0.094 | 0.123 | −0.004 |
Concentration problems | 0.465 | 0.624 | 0.121 | 0.056 | 0.060 | 0.060 | 0.055 | 0.111 | 0.099 | 0.112 | −0.125 |
Disorientation | 0.070 | 0.587 | 0.072 | 0.246 | 0.273 | 0.083 | 0.179 | 0.194 | −0.024 | 0.037 | 0.176 |
Memory problems | 0.174 | 0.572 | 0.132 | 0.126 | −0.017 | 0.096 | 0.147 | 0.285 | 0.272 | 0.049 | −0.114 |
Clumsiness | 0.197 | 0.572 | 0.279 | 0.031 | 0.446 | 0.077 | 0.032 | 0.194 | 0.084 | 0.077 | 0.052 |
Confusion | 0.050 | 0.559 | 0.112 | 0.354 | 0.092 | 0.113 | 0.214 | 0.171 | −0.023 | 0.016 | 0.118 |
Dry mouth | 0.412 | 0.093 | 0.606 | −0.053 | 0.070 | −0.009 | 0.039 | 0.086 | 0.252 | 0.098 | −0.051 |
Thirst | 0.456 | 0.098 | 0.583 | −0.056 | 0.135 | 0.021 | −0.007 | 0.083 | 0.248 | 0.131 | −0.003 |
Hot/cold flashes | 0.052 | 0.120 | 0.570 | 0.210 | 0.039 | 0.193 | 0.259 | 0.061 | −0.016 | 0.135 | −0.029 |
Shivering | 0.078 | 0.244 | 0.518 | 0.136 | 0.280 | 0.352 | 0.215 | −0.090 | 0.022 | 0.212 | −0.018 |
Tremor | 0.100 | 0.286 | 0.500 | 0.103 | 0.244 | 0.305 | 0.200 | −0.106 | 0.002 | 0.188 | −0.076 |
Sweating | 0.101 | 0.055 | 0.395 | 0.146 | 0.199 | 0.147 | 0.270 | 0.311 | 0.073 | 0.215 | 0.026 |
Muscle pain | 0.150 | 0.192 | 0.392 | 0.176 | 0.164 | 0.098 | 0.037 | 0.228 | 0.008 | −0.064 | 0.189 |
Nystagmus | 0.004 | 0.166 | 0.367 | 0.193 | 0.019 | 0.271 | 0.211 | 0.312 | −0.139 | 0.024 | 0.067 |
Anxiety | 0.074 | 0.086 | −0.037 | 0.711 | −0.064 | 0.106 | 0.188 | 0.028 | 0.131 | 0.141 | −0.104 |
Depression | 0.172 | 0.095 | 0.080 | 0.709 | 0.055 | 0.065 | 0.136 | 0.176 | 0.171 | 0.025 | −0.070 |
Anger | 0.008 | 0.108 | 0.134 | 0.657 | 0.178 | 0.106 | 0.012 | 0.103 | 0.075 | 0.087 | 0.244 |
Agitation | 0.317 | 0.138 | 0.279 | 0.453 | 0.248 | 0.021 | −0.032 | 0.065 | −0.038 | 0.100 | −0.074 |
Dizziness | 0.157 | 0.197 | 0.124 | 0.039 | 0.697 | 0.270 | 0.187 | 0.124 | 0.265 | 0.075 | −0.085 |
Vertigo | 0.176 | 0.260 | 0.110 | 0.003 | 0.685 | 0.257 | 0.161 | 0.099 | 0.262 | 0.128 | −0.053 |
Balance problems | 0.067 | 0.496 | 0.254 | 0.089 | 0.565 | 0.108 | 0.035 | 0.139 | 0.094 | 0.087 | 0.082 |
Tinnitus | 0.101 | 0.025 | 0.140 | 0.213 | 0.543 | −0.034 | 0.139 | 0.199 | −0.186 | 0.082 | 0.061 |
Stomach pain | 0.161 | 0.043 | 0.064 | 0.074 | 0.066 | 0.774 | 0.093 | 0.119 | 0.125 | 0.001 | 0.026 |
Gastrointestinal complaints | 0.153 | 0.120 | 0.243 | 0.098 | 0.060 | 0.676 | 0.072 | 0.194 | 0.106 | −0.110 | 0.017 |
Gastritis | 0.048 | 0.135 | 0.150 | 0.060 | 0.110 | 0.532 | 0.213 | −0.032 | 0.017 | 0.147 | 0.066 |
Nausea | 0.245 | 0.008 | −0.032 | 0.042 | 0.299 | 0.481 | −0.014 | 0.013 | 0.428 | 0.229 | −0.110 |
Heart pounding | 0.122 | 0.143 | 0.132 | 0.139 | 0.118 | 0.077 | 0.845 | 0.047 | 0.081 | 0.050 | −0.063 |
Palipitations | 0.092 | 0.173 | 0.100 | 0.095 | 0.099 | 0.171 | 0.844 | 0.021 | 0.033 | 0.080 | −0.020 |
Respiratory problems | 0.037 | 0.004 | 0.167 | 0.115 | 0.129 | 0.120 | 0.593 | 0.250 | 0.075 | 0.102 | 0.198 |
Loss of taste | 0.049 | 0.189 | 0.309 | −0.020 | 0.048 | 0.084 | 0.076 | 0.579 | 0.214 | 0.202 | −0.222 |
Impulsivity | 0.081 | 0.113 | −0.045 | 0.097 | 0.244 | 0.011 | 0.125 | 0.554 | 0.158 | 0.023 | 0.294 |
Restlessness | 0.267 | 0.203 | −0.008 | 0.228 | 0.180 | 0.217 | 0.034 | 0.553 | −0.019 | 0.060 | −0.059 |
Blunted affect | 0.175 | 0.334 | 0.093 | 0.277 | 0.112 | 0.011 | 0.083 | 0.495 | 0.019 | 0.092 | 0.038 |
Guilt | 0.084 | 0.158 | 0.185 | 0.336 | 0.032 | −0.005 | 0.159 | 0.216 | 0.651 | −0.154 | 0.199 |
Regret | 0.087 | 0.209 | 0.200 | 0.445 | 0.061 | 0.000 | 0.126 | 0.095 | 0.593 | −0.101 | 0.157 |
Vomiting | −0.022 | 0.067 | −0.023 | 0.074 | 0.132 | 0.380 | −0.001 | −0.018 | 0.586 | 0.095 | −0.043 |
Reduced appetite | 0.165 | 0.055 | 0.117 | −0.015 | 0.012 | 0.183 | 0.059 | 0.260 | 0.407 | 0.240 | −0.439 |
Audio-sensitivity | 0.068 | 0.235 | 0.170 | 0.098 | 0.037 | 0.068 | 0.115 | 0.152 | 0.021 | 0.748 | 0.091 |
Photo-sensitivity | 0.066 | 0.156 | 0.213 | 0.169 | 0.155 | −0.024 | 0.126 | 0.070 | 0.018 | 0.735 | 0.181 |
Headache | 0.416 | −0.052 | 0.003 | 0.014 | 0.122 | 0.112 | 0.009 | 0.031 | −0.011 | 0.451 | −0.053 |
Suicidal thoughts | 0.033 | 0.058 | 0.011 | 0.000 | −0.029 | 0.084 | 0.047 | 0.065 | 0.092 | 0.234 | 0.771 |
. | Factor . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
. | 1 . | 2 . | 3 . | 4 . | 5 . | 6 . | 7 . | 8 . | 9 . | 10 . | 11 . |
Explained variance (%) | 28.8 | 5.9 | 4.5 | 4.1 | 3.5 | 3.0 | 2.7 | 2.5 | 2.5 | 2.3 | 2.2 |
Cumulative (%) | 28.8 | 34.6 | 39.1 | 43.2 | 46.7 | 47.7 | 52.4 | 54.9 | 57.4 | 59.7 | 62.0 |
Fatigue (being tired) | 0.834 | 0.163 | 0.075 | 0.091 | 0.075 | 0.091 | 0.081 | 0.057 | 0.019 | −0.017 | 0.016 |
Sleepiness | 0.798 | 0.160 | 0.081 | 0.085 | 0.082 | 0.108 | 0.081 | 0.083 | 0.007 | −0.013 | 0.069 |
Drowsiness | 0.727 | 0.273 | 0.112 | 0.057 | 0.049 | 0.090 | 0.089 | 0.042 | −0.006 | 0.074 | 0.066 |
Apathy (lack of interest/concern) | 0.623 | 0.186 | 0.152 | 0.181 | 0.051 | 0.074 | 0.036 | 0.243 | 0.082 | 0.118 | −0.102 |
Weakness | 0.511 | 0.343 | 0.257 | 0.156 | 0.178 | 0.152 | 0.051 | 0.008 | 0.197 | 0.146 | −0.023 |
Increased reaction time | 0.385 | 0.715 | 0.108 | 0.019 | 0.106 | 0.101 | 0.035 | 0.046 | 0.084 | 0.161 | 0.033 |
Reduced alertness | 0.448 | 0.703 | 0.095 | 0.035 | 0.104 | 0.080 | 0.050 | 0.042 | 0.094 | 0.123 | −0.004 |
Concentration problems | 0.465 | 0.624 | 0.121 | 0.056 | 0.060 | 0.060 | 0.055 | 0.111 | 0.099 | 0.112 | −0.125 |
Disorientation | 0.070 | 0.587 | 0.072 | 0.246 | 0.273 | 0.083 | 0.179 | 0.194 | −0.024 | 0.037 | 0.176 |
Memory problems | 0.174 | 0.572 | 0.132 | 0.126 | −0.017 | 0.096 | 0.147 | 0.285 | 0.272 | 0.049 | −0.114 |
Clumsiness | 0.197 | 0.572 | 0.279 | 0.031 | 0.446 | 0.077 | 0.032 | 0.194 | 0.084 | 0.077 | 0.052 |
Confusion | 0.050 | 0.559 | 0.112 | 0.354 | 0.092 | 0.113 | 0.214 | 0.171 | −0.023 | 0.016 | 0.118 |
Dry mouth | 0.412 | 0.093 | 0.606 | −0.053 | 0.070 | −0.009 | 0.039 | 0.086 | 0.252 | 0.098 | −0.051 |
Thirst | 0.456 | 0.098 | 0.583 | −0.056 | 0.135 | 0.021 | −0.007 | 0.083 | 0.248 | 0.131 | −0.003 |
Hot/cold flashes | 0.052 | 0.120 | 0.570 | 0.210 | 0.039 | 0.193 | 0.259 | 0.061 | −0.016 | 0.135 | −0.029 |
Shivering | 0.078 | 0.244 | 0.518 | 0.136 | 0.280 | 0.352 | 0.215 | −0.090 | 0.022 | 0.212 | −0.018 |
Tremor | 0.100 | 0.286 | 0.500 | 0.103 | 0.244 | 0.305 | 0.200 | −0.106 | 0.002 | 0.188 | −0.076 |
Sweating | 0.101 | 0.055 | 0.395 | 0.146 | 0.199 | 0.147 | 0.270 | 0.311 | 0.073 | 0.215 | 0.026 |
Muscle pain | 0.150 | 0.192 | 0.392 | 0.176 | 0.164 | 0.098 | 0.037 | 0.228 | 0.008 | −0.064 | 0.189 |
Nystagmus | 0.004 | 0.166 | 0.367 | 0.193 | 0.019 | 0.271 | 0.211 | 0.312 | −0.139 | 0.024 | 0.067 |
Anxiety | 0.074 | 0.086 | −0.037 | 0.711 | −0.064 | 0.106 | 0.188 | 0.028 | 0.131 | 0.141 | −0.104 |
Depression | 0.172 | 0.095 | 0.080 | 0.709 | 0.055 | 0.065 | 0.136 | 0.176 | 0.171 | 0.025 | −0.070 |
Anger | 0.008 | 0.108 | 0.134 | 0.657 | 0.178 | 0.106 | 0.012 | 0.103 | 0.075 | 0.087 | 0.244 |
Agitation | 0.317 | 0.138 | 0.279 | 0.453 | 0.248 | 0.021 | −0.032 | 0.065 | −0.038 | 0.100 | −0.074 |
Dizziness | 0.157 | 0.197 | 0.124 | 0.039 | 0.697 | 0.270 | 0.187 | 0.124 | 0.265 | 0.075 | −0.085 |
Vertigo | 0.176 | 0.260 | 0.110 | 0.003 | 0.685 | 0.257 | 0.161 | 0.099 | 0.262 | 0.128 | −0.053 |
Balance problems | 0.067 | 0.496 | 0.254 | 0.089 | 0.565 | 0.108 | 0.035 | 0.139 | 0.094 | 0.087 | 0.082 |
Tinnitus | 0.101 | 0.025 | 0.140 | 0.213 | 0.543 | −0.034 | 0.139 | 0.199 | −0.186 | 0.082 | 0.061 |
Stomach pain | 0.161 | 0.043 | 0.064 | 0.074 | 0.066 | 0.774 | 0.093 | 0.119 | 0.125 | 0.001 | 0.026 |
Gastrointestinal complaints | 0.153 | 0.120 | 0.243 | 0.098 | 0.060 | 0.676 | 0.072 | 0.194 | 0.106 | −0.110 | 0.017 |
Gastritis | 0.048 | 0.135 | 0.150 | 0.060 | 0.110 | 0.532 | 0.213 | −0.032 | 0.017 | 0.147 | 0.066 |
Nausea | 0.245 | 0.008 | −0.032 | 0.042 | 0.299 | 0.481 | −0.014 | 0.013 | 0.428 | 0.229 | −0.110 |
Heart pounding | 0.122 | 0.143 | 0.132 | 0.139 | 0.118 | 0.077 | 0.845 | 0.047 | 0.081 | 0.050 | −0.063 |
Palipitations | 0.092 | 0.173 | 0.100 | 0.095 | 0.099 | 0.171 | 0.844 | 0.021 | 0.033 | 0.080 | −0.020 |
Respiratory problems | 0.037 | 0.004 | 0.167 | 0.115 | 0.129 | 0.120 | 0.593 | 0.250 | 0.075 | 0.102 | 0.198 |
Loss of taste | 0.049 | 0.189 | 0.309 | −0.020 | 0.048 | 0.084 | 0.076 | 0.579 | 0.214 | 0.202 | −0.222 |
Impulsivity | 0.081 | 0.113 | −0.045 | 0.097 | 0.244 | 0.011 | 0.125 | 0.554 | 0.158 | 0.023 | 0.294 |
Restlessness | 0.267 | 0.203 | −0.008 | 0.228 | 0.180 | 0.217 | 0.034 | 0.553 | −0.019 | 0.060 | −0.059 |
Blunted affect | 0.175 | 0.334 | 0.093 | 0.277 | 0.112 | 0.011 | 0.083 | 0.495 | 0.019 | 0.092 | 0.038 |
Guilt | 0.084 | 0.158 | 0.185 | 0.336 | 0.032 | −0.005 | 0.159 | 0.216 | 0.651 | −0.154 | 0.199 |
Regret | 0.087 | 0.209 | 0.200 | 0.445 | 0.061 | 0.000 | 0.126 | 0.095 | 0.593 | −0.101 | 0.157 |
Vomiting | −0.022 | 0.067 | −0.023 | 0.074 | 0.132 | 0.380 | −0.001 | −0.018 | 0.586 | 0.095 | −0.043 |
Reduced appetite | 0.165 | 0.055 | 0.117 | −0.015 | 0.012 | 0.183 | 0.059 | 0.260 | 0.407 | 0.240 | −0.439 |
Audio-sensitivity | 0.068 | 0.235 | 0.170 | 0.098 | 0.037 | 0.068 | 0.115 | 0.152 | 0.021 | 0.748 | 0.091 |
Photo-sensitivity | 0.066 | 0.156 | 0.213 | 0.169 | 0.155 | −0.024 | 0.126 | 0.070 | 0.018 | 0.735 | 0.181 |
Headache | 0.416 | −0.052 | 0.003 | 0.014 | 0.122 | 0.112 | 0.009 | 0.031 | −0.011 | 0.451 | −0.053 |
Suicidal thoughts | 0.033 | 0.058 | 0.011 | 0.000 | −0.029 | 0.084 | 0.047 | 0.065 | 0.092 | 0.234 | 0.771 |
Shaded bold printed factor loadings indicate the factor to which a symptom belongs.
The most prominent factor ‘drowsiness’ (R2 = 28.8%) included symptoms such as drowsiness, fatigue, sleepiness and weakness. The second factor ‘cognitive problems’ (R2 = 5.9%) included symptoms such as reduced alertness, memory and concentration problems. In contrast, other factors, including the factor ‘disturbed water balance’ comprising frequently reported symptoms such as ‘dry mouth’ and ‘thirst’, contributed much less to the overall hangover (R2 <5%). Table 3 shows that the scores on all factors correlate significantly with the overall hangover score. Also, Cronbach's alpha of most scales was acceptable (>0.70).
. | Cronbach's alpha . | . | . | . | . | . | . | . | . | . | . | . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
F1 (drowsiness) | 0.86 | 0.761 | ||||||||||
F2 (cognitive problems) | 0.88 | 0.843 | 0.631 | |||||||||
F3 (disturbed water balance) | 0.80 | 0.836 | 0.560 | 0.604 | ||||||||
F4 (mood disturbances) | 0.64 | 0.632 | 0.437 | 0.480 | 0.470 | |||||||
F5 (balance problems) | 0.79 | 0.761 | 0.445 | 0.629 | 0.590 | 0.412 | ||||||
F6 (gastrointestinal problems) | 0.70 | 0.656 | 0.383 | 0.412 | 0.498 | 0.341 | 0.519 | |||||
F7 (respiratory and cardiovascular problems) | 0.80 | 0.554 | 0.301 | 0.394 | 0.483 | 0.351 | 0.409 | 0.373 | ||||
F8 (impulsivity and blunted affect) | 0.65 | 0.712 | 0.460 | 0.603 | 0.513 | 0.500 | 0.527 | 0.349 | 0.362 | |||
F9 (vomiting and feeling guilty) | 0.64 | 0.623 | 0.362 | 0.415 | 0.451 | 0.396 | 0.430 | 0.505 | 0.312 | 0.431 | ||
F10 (headache) | 0.60 | 0.569 | 0.382 | 0.402 | 0.471 | 0.327 | 0.372 | 0.256 | 0.297 | 0.348 | 0.287 | |
F11 (suicidal thoughts) | – | 0.167 | 0.085 | 0.123 | 0.133 | 0.107 | 0.101 | 0.072 | 0.119 | 0.152 | 0.058 | 0.166 |
Overall | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 |
. | Cronbach's alpha . | . | . | . | . | . | . | . | . | . | . | . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
F1 (drowsiness) | 0.86 | 0.761 | ||||||||||
F2 (cognitive problems) | 0.88 | 0.843 | 0.631 | |||||||||
F3 (disturbed water balance) | 0.80 | 0.836 | 0.560 | 0.604 | ||||||||
F4 (mood disturbances) | 0.64 | 0.632 | 0.437 | 0.480 | 0.470 | |||||||
F5 (balance problems) | 0.79 | 0.761 | 0.445 | 0.629 | 0.590 | 0.412 | ||||||
F6 (gastrointestinal problems) | 0.70 | 0.656 | 0.383 | 0.412 | 0.498 | 0.341 | 0.519 | |||||
F7 (respiratory and cardiovascular problems) | 0.80 | 0.554 | 0.301 | 0.394 | 0.483 | 0.351 | 0.409 | 0.373 | ||||
F8 (impulsivity and blunted affect) | 0.65 | 0.712 | 0.460 | 0.603 | 0.513 | 0.500 | 0.527 | 0.349 | 0.362 | |||
F9 (vomiting and feeling guilty) | 0.64 | 0.623 | 0.362 | 0.415 | 0.451 | 0.396 | 0.430 | 0.505 | 0.312 | 0.431 | ||
F10 (headache) | 0.60 | 0.569 | 0.382 | 0.402 | 0.471 | 0.327 | 0.372 | 0.256 | 0.297 | 0.348 | 0.287 | |
F11 (suicidal thoughts) | – | 0.167 | 0.085 | 0.123 | 0.133 | 0.107 | 0.101 | 0.072 | 0.119 | 0.152 | 0.058 | 0.166 |
Overall | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 |
All factors correlated significantly (P < 0.05), except F6 and F11 and F9 and F11.
No Cronbach's alpha was computed for Factor 11, since it contains only one item.
. | Cronbach's alpha . | . | . | . | . | . | . | . | . | . | . | . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
F1 (drowsiness) | 0.86 | 0.761 | ||||||||||
F2 (cognitive problems) | 0.88 | 0.843 | 0.631 | |||||||||
F3 (disturbed water balance) | 0.80 | 0.836 | 0.560 | 0.604 | ||||||||
F4 (mood disturbances) | 0.64 | 0.632 | 0.437 | 0.480 | 0.470 | |||||||
F5 (balance problems) | 0.79 | 0.761 | 0.445 | 0.629 | 0.590 | 0.412 | ||||||
F6 (gastrointestinal problems) | 0.70 | 0.656 | 0.383 | 0.412 | 0.498 | 0.341 | 0.519 | |||||
F7 (respiratory and cardiovascular problems) | 0.80 | 0.554 | 0.301 | 0.394 | 0.483 | 0.351 | 0.409 | 0.373 | ||||
F8 (impulsivity and blunted affect) | 0.65 | 0.712 | 0.460 | 0.603 | 0.513 | 0.500 | 0.527 | 0.349 | 0.362 | |||
F9 (vomiting and feeling guilty) | 0.64 | 0.623 | 0.362 | 0.415 | 0.451 | 0.396 | 0.430 | 0.505 | 0.312 | 0.431 | ||
F10 (headache) | 0.60 | 0.569 | 0.382 | 0.402 | 0.471 | 0.327 | 0.372 | 0.256 | 0.297 | 0.348 | 0.287 | |
F11 (suicidal thoughts) | – | 0.167 | 0.085 | 0.123 | 0.133 | 0.107 | 0.101 | 0.072 | 0.119 | 0.152 | 0.058 | 0.166 |
Overall | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 |
. | Cronbach's alpha . | . | . | . | . | . | . | . | . | . | . | . |
---|---|---|---|---|---|---|---|---|---|---|---|---|
F1 (drowsiness) | 0.86 | 0.761 | ||||||||||
F2 (cognitive problems) | 0.88 | 0.843 | 0.631 | |||||||||
F3 (disturbed water balance) | 0.80 | 0.836 | 0.560 | 0.604 | ||||||||
F4 (mood disturbances) | 0.64 | 0.632 | 0.437 | 0.480 | 0.470 | |||||||
F5 (balance problems) | 0.79 | 0.761 | 0.445 | 0.629 | 0.590 | 0.412 | ||||||
F6 (gastrointestinal problems) | 0.70 | 0.656 | 0.383 | 0.412 | 0.498 | 0.341 | 0.519 | |||||
F7 (respiratory and cardiovascular problems) | 0.80 | 0.554 | 0.301 | 0.394 | 0.483 | 0.351 | 0.409 | 0.373 | ||||
F8 (impulsivity and blunted affect) | 0.65 | 0.712 | 0.460 | 0.603 | 0.513 | 0.500 | 0.527 | 0.349 | 0.362 | |||
F9 (vomiting and feeling guilty) | 0.64 | 0.623 | 0.362 | 0.415 | 0.451 | 0.396 | 0.430 | 0.505 | 0.312 | 0.431 | ||
F10 (headache) | 0.60 | 0.569 | 0.382 | 0.402 | 0.471 | 0.327 | 0.372 | 0.256 | 0.297 | 0.348 | 0.287 | |
F11 (suicidal thoughts) | – | 0.167 | 0.085 | 0.123 | 0.133 | 0.107 | 0.101 | 0.072 | 0.119 | 0.152 | 0.058 | 0.166 |
Overall | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 |
All factors correlated significantly (P < 0.05), except F6 and F11 and F9 and F11.
No Cronbach's alpha was computed for Factor 11, since it contains only one item.
DISCUSSION
This is the first attempt to categorize reported hangover symptoms into groups of symptoms that are associated with each other. The results show that drowsiness and reduced cognitive functioning are the most prominent factors determining overall hangover severity. Our findings further show that not all frequently reported symptoms that are related to excessive alcohol consumption contribute equally to alcohol hangover. In fact, some symptoms such as dry mouth and thirst seem related to other consequences of excessive alcohol consumption such as dehydration.
Rohsenow et al. (2007) also found being tired (fatigue) and thirsty as most severe hangover symptoms, although in opposite order of the results of this survey. This is remarkable, since it has been suggested that these symptoms are primarily the result of sleep deprivation and dehydration, respectively (Verster et al., 2010). Yet, Rohsenow et al. (2007) controlled for sleep and liquid intake on the alcohol and placebo nights. These effects and their differential cause supports the notion by Ylikahri et al. (1974) that the alcohol hangover does not have a single cause that leads to one condition, but should be viewed as a syndrome. In other words, multiple physiological, metabolic and neuroimmunological effects are provoked by alcohol consumption that together sum up to the total hangover experience. Ylikahri et al. (1974) showed that nausea, fatigue, thirst and tension correlated best with the overall hangover severity. In our study, thirst, fatigue and nausea were also listed in the top 10 of most frequently reported hangover symptoms.
Yilkhari et al. showed that subjectively experienced symptoms had a high degree of correlation with total hangover score and therefore can be used as a measurement of hangover. However, they further showed that signs such as tremor (objectively observed by the researcher) also showed good correlation with a total hangover score. Therefore, it can be discussed whether only symptoms or only signs should be used as a measurement for alcohol hangover severity or that combining signs and symptoms is the best way to express alcohol hangover (Ylikahri et al., 1974). The current study was limited to self-reported symptoms. A controlled study is required to determine whether additional signs are present during the hangover state that are not readily experienced as symptoms (e.g. a small increase in blood pressure) and therefore not self-reported.
When compared with the categorization of Swift and Davidson (1998), our factor analysis showed some different factor composition, but also some similarity. The most prominent factors, drowsiness and cognitive problems, were also proposed by Swift and Davidson. Some symptoms however should, according to our analysis, contribute to a different factor. For example, thirst should not be placed in the constitutional/drowsiness category, but in a factor labeled ‘disturbed water balance’.
A limitation of this research is that data were collected retrospectively, and thus recall bias may have played a role. On the other hand, a listing of 47 symptoms was presented to the participants aiding recall and facilitating a decision as to whether or not they experienced particular symptoms. The fact that our sample was a convenience sample is not a limitation in research that aims to establish associations between symptoms.
The categorization into 11 factors explains 62% of the variance, which means that 38% is still unexplained. This relatively large portion of unexplained variance is not surprising since the pathology of alcohol hangover has not been established (Penning et al., 2010). Moreover, various factors in addition to alcohol may influence hangover severity. Future research should focus on these factors, including but not limited to, congeners, physical activity (e.g. dancing), smoking and drug use, and personality (Verster et al., 2010).
Funding
The past 3 years, J.C.V. has received research support from Takeda Pharmaceuticals and Red Bull GmbH, and was scientific advisor for Takeda, Sanofi-Aventis, Transcept, Sepracor, Red Bull GmbH, Deenox, Trimbos Institute and CBD.
Conflict of interest statement. The authors have no conflicts of interest to disclose.