1 Division of Health Promotion, Department of Public Health, University of Tartu, Ravila 19, 50411 Tartu, Estonia and 2 Department of Psychology, University of Tartu, Centre of Behavioural and Health Sciences, Tiigi 78, 50410 Tartu, Estonia
* Author to whom correspondence should be addressed at: Tel.: +372 7 375911; Fax: +372 7 375900; E-mail: jaanus.harro{at}ut.ee
(Received 27 May 2004; first review notified 26 August 2004; in revised form 2 November 2004; accepted 14 December 2004)
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ABSTRACT |
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INTRODUCTION |
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Personality traits are the underlying factors affecting peoples' estimations, attitudes and behavioural decisions. One of the most studied traits in association with risky driving is sensation seeking (Jonah, 1997; Iversen and Rundmo, 2002
). Sensation seeking, which is sometimes also referred to as novelty or excitement seeking, is a trait described by the constant need for novel and intense sensations and experiences. Another trait commonly associated with risk taking and rule breaking, as well as alcohol-related problems, is impulsivity (von Knorring and Oreland, 1996
). The association between impulsivity, risky driving and motor vehicle crash injuries has also been shown (Hilakivi et al., 1989
; Cherpitel and Tam, 2000
). Impulsivity is defined by a range of various tendencies, including rapid and thoughtless action, low self-control, risk-taking and the inability to hold back one's desires.
It is known that genetic factors predict about half of the variance of personality traits, depending on the variety of environmental impacts. Social maladaptation and personality traits such as impulsivity, sensation seeking and monotony avoidance have been correlated with low levels of monoamine oxidase (MAO) activity in platelets, which is a peripheral marker of serotonergic activity in the central nervous system (von Knorring et al., 1984; Oreland, 2004
). Platelet MAO activity is also lower in alcohol-dependent subjects (Cloninger et al., 1988
; von Knorring and Oreland, 1996
). It has been proposed that risky driving has a common biological basis with sensation seeking (Jonah, 1997
). Nevertheless, empirical support for such assumptions is scarce.
We have compared a group of police-referred drunk drivers with a group of controls, taking into account self-reported drinking and driving, socio-economic variables, usual alcohol consumption, smoking, other risky traffic behaviour habits, impulsivity measures and platelet MAO activity.
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METHODS |
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The Ethics Committee at the Faculty of Medicine of the University of Tartu approved this study.
Socio-economic background, smoking, alcohol use and traffic behaviour
Subjects reported their socio-economic status, smoking, alcohol use habits and traffic behaviour in a self-reported questionnaire. Questions about socio-economic background included marital status, education, monthly income, occupation and religiousness. Based on self-reported smoking behaviour, the subjects were divided into non-smokers, ex-smokers and smokers who smoked 10 cigarettes per day, 1119 cigarettes per day and
20 cigarettes per day. For evaluating alcohol consumption habits, the questionnaire contained items about the frequency of using strong and light alcoholic drinks during the previous year on a 6-point scale (none, some times during the year, one to three times per month, one to two times per week, three to four times per week, almost every day). The amount of alcohol consumed during the previous week before the study was evaluated on the basis of the amount of different alcoholic drinks and was expressed in grams of pure alcohol. The score of alcohol-related problems was obtained by summing up five questions based on the DSM-IV diagnostic criteria for alcohol abuse, relating to specific life events (having turned aggressive while drunk, having had longer periods of alcohol use, having had conflicts with friends and family, having been absent from work, and having lost one's job; reported as present or not, total score 05). Questions relating to traffic behaviour habits such as the frequency of car driving, using the seat belt, exceeding the speed limits, paying for parking, stopping before a zebra crossing and overtaking during the previous year, as well as the duration of having a driving licence, were included. The subjects were also asked about driving while impaired by alcohol during the previous year. In addition, the knowledge of time limits for safe drinking before driving was checked.
Personality measures
Impulsivity was measured by a short instrument based on Dickman Impulsivity Inventory (Dickman, 1990) and impulsivity-related subscales of NEO Personality Inventory (NEO-PI, Costa and McCrae, 1989
). Altogether, four scales were formedDysfunctional and Functional Impulsivity based on Dickman Inventory, and Impulsivity and Excitement Seeking based on NEO-PI subscales. Each of the four scales consisted of six items.
Measurement of platelet MAO activity
Venous blood samples were collected into 4.5 ml vacutainers containing K3EDTA as an anticoagulant. MAO activity was analysed in platelet-rich plasma by a radioenzymatic method with [14C]-ß-phenylethylamine as the substrate, according to the procedure described by Hallman et al. (1987) and Harro et al. (2001)
. All samples were analysed in duplicate and blindly, and corrected using a reference sample. MAO activity is expressed as nanomoles of substrate oxidized per 1010 platelets per minute.
Statistical analysis
Nominal variables were described using frequency tables. Pearson's Chi-square test with post hoc analysis of individual cell contributions was used. If a significant difference was found with analysis of variance (ANOVA), Fisher's multiple comparison procedure was used. Covariation analysis (ANCOVA) was used for controlling the effect of the third variable if significant effects were revealed in the ANOVA analyses. KruskalWallis test was used for comparing the nonparametrically distributed variables. Spearman's correlation analysis was used. Discriminant analysis was performed to identify the combination of quantitative variables that predict drunk driving.
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RESULTS |
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Socio-economic background, smoking and alcohol use habits
The four groups did not differ by marital status, monthly income or by occupational categories (data not shown). Statistically significant differences appeared with respect to median age, education, belief in religion, smoking behaviour, frequency of using strong and light alcoholic drinks, the amount of alcohol consumed in the past week before the study and having alcohol-related problems (Table 1). The median age of the DWI II group's subjects was significantly lower, compared with other groups. The subjects of the DWI II group also had a lower educational level compared with both control groups. In the DWI II group, there were more subjects who had elementary to high school education, and fewer subjects who had a university education compared with the control groups. The Control I group was clearly different from the other groups with respect to religiousness, smoking status and alcohol consumption habits. There were more religious subjects and non-smokers in the Control I group, and the use of strong and light alcohol was also lower among the Control I group when compared with the other groups. While the DWI II group did not differ from the Control II group by the amount of alcohol consumed during the previous week and by the frequency of using light alcoholic drinks, the score of alcohol-related problems and frequency of using strong alcoholic drinks were higher in the DWI II group.
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Platelet MAO activity
Mean values of platelet MAO activity were 8.3 ± 4.1(SD), 7.7 ± 4.1, 6.2 ± 2.2 and 6.7 ± 4.5 nmol/1010 platelets/min for Control I, Control II, DWI I, and DWI II groups, respectively. After logarithmic transformation of MAO activity, ANOVA and Fisher's multiple comparison procedure was performed. The DWI I and DWI II groups' mean MAO activities were both significantly lower compared with the Control I and Control II groups (F3,399 = 7.51, P < 0.0001; Fig. 1). Platelet MAO activity was significantly negatively correlated with alcohol-related problems (r = 0.20, P < 0.0001) but not with any measures of alcohol consumption.
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DISCUSSION |
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Socio-economic background of the groups was quite similar, except that a lower educational level was overrepresented in the DWI-groups and religiousness in the Control I group. Previous studies have described different (Baum, 2000) as well as a similar (Wilson and Jonah, 1985
) socio-economic background of the drunk drivers and controls. In our study, the variables describing the socio-economic background did not appear as independent predictors of drunk driving in discriminant analysis, which suggests that their significance is closely related to other factors.
DWI subjects, who self-reported driving after drinking (DWI II), appeared to be the youngest group. At present, it remains unclear whether older drivers lie more about their drunk driving or whether they were caught more often in a hangover, thus, not acknowledging their drinking and driving problem. Investigations of drunk drivers who had caused traffic accidents, as well as population studies, show that younger drivers tend to drive after drinking, more often (Wilson and Jonah, 1985; Johnson et al., 1998
; Golias and Karlaftis, 2002
).
As expected, the DWI subjects who reported drunk driving consumed more alcohol in the previous 7 days in comparison with the other groups. Out of alcohol-related variables, the best discriminating indicators appeared to be alcohol-related problems and the frequency of using alcohol. It has been found that drunk driving incidents are more frequent among drivers having alcohol-related problems (Del Rio et al., 2001). Johnson et al. (1998)
described both the frequency of drinking and the amount of consumed alcohol as predictors of drunk driving. With respect to alcohol consumption measures, DWI subjects who denied drunk driving were similar to the subjects of the Control I group by the frequency of using light alcoholic drinks; in the use of strong alcoholic drinks, they were placed in between controls and drunk driving reporters. They also reported consuming less alcohol compared with the groups who reported drunk driving. It is possible that they were caught in a hangover without being aware of their blood alcohol levels. Alternatively, they may have underreported their alcohol consumption. We do not know whether this reflects their bigger reporting bias in general.
Subjects who were caught driving while impaired, and reported this in the questionnaire (DWI II group), reported more often their generally careless traffic behaviour and violation of other traffic rules. They reported using a seat belt and paying for parking more rarely, and exceeding speed limits more often. This group also included more subjects who had been driving without having a valid driving licence, and novice drivers. In the investigations of drunk drivers, similar differences in low seat belt use, speeding (Golias and Karlaftis, 2002), driving without a driving licence (Baum, 2000
; Begg et al., 2003
) and novice driving (Cooper et al., 1995
) have been described. In our study, drunk drivers and controls were discriminated significantly by seat belt use and paying for parking.
Knowledge about safe time limits for drinking before driving was quite low, which suggests that such information should be included in the DWI prevention programmes. It has been shown that knowledge about drunk driving improves after participating in a DWI prevention programme (Kayser et al., 1995). DWI I group subjects had a lower level of knowledge about time limits for safe drinking before driving, compared with other groups, which might be the reason for underreporting their drunk driving. On the contrary, among the DWI II group, subjects' knowledge about time limits for safe drinking before driving was a little better in our study compared with the other groups. This might be explained by the fact that there were more subjects having a driving licence for
2 years in the DWI II group and who hence better remember the time limits for safe drinking before driving from their studies. However, this knowledge does not reflect in their actual driving habits, as other variables such as their higher level of impulsivity and alcohol use habits have a stronger impact.
Drunk drivers had a higher dysfunctional impulsivity and NEO-PI impulsivity. Dysfunctional impulsivity, which appeared to be the best predictor of drinking and driving, is a feature of cognitive style, supporting quick and thoughtless action in complex situations, where this kind of information processing leads to errors and inaccuracy (Dickman, 1990). This information-processing style might bring along their inadequate estimation of the risk, when deciding to drive after drinking. Functional impulsivity, which is defined as adaptive and situation-specific, was not associated with drinking and driving. The difference between the groups in NEO-PI impulsivity, characterized by problems with controlling one's wishes and impulses, decreased after taking age into account. The difference between the groups in excitement seeking appeared to be mostly due to the younger average age of the group of drunk drivers.
Earlier studies have shown the association of platelet MAO activity with risky behavioural tendencies (Fowler et al., 1980), social maladaptation (Oreland, 2004
) and alcohol dependence (von Knorring and Oreland, 1996
). Platelet MAO activity is a peripheral marker for the activity of the central serotonin system due to a postulated common genetic control (Oreland, 2004
) that could occur via common gene promoter sequences and co-regulation of platelet MAO and monoamine transmitter genes. Recently, the ability of the platelet MAO activity to predict central serotonergic activity was further confirmed by the finding that there is a strong correlation between cerebrospinal fluid levels of the serotonin metabolite 5-HIAA and platelet MAO activity (Fahlke et al., 2002
). These authors also found that rhesus macaques with low platelet MAO activity were less competent socially, and consumed alcohol to excess. In our study, platelet MAO activity was negatively correlated with alcohol-related problems but not with any measures of alcohol consumption. Studies with alcohol-dependent subjects have found that low MAO activity in platelets is associated with type 2 alcoholism (Cloninger et al., 1988
; von Knorring and Oreland, 1996
), which is characterized by several social complications and an early debut of the abuse (Oreland, 2004
). Our results also lead to an assumption that MAO activity is more strongly related to the tendency for an alcohol-related problem behaviour than to the tendency to consume more alcohol. In both DWI groups, platelet MAO activity was significantly lower compared with both control groups. Drunk driving deniers and reporters in the DWI group did not differ with respect to MAO activity. The present discriminant analysis identified smoking and platelet MAO activity as separate significant factors in predicting drinking and driving. However, platelet MAO activity is directly reduced by tobacco smoking, and this has been suggested to underlie the low MAO activity in alcohol abusers (Whitfield et al., 2000
). In a preliminary analysis, we compared the police-referred drunk drivers with controls, with respect to the intensity of smoking and found that the platelet MAO activity of non-smokers among DWI subjects was lower in comparison with the non-smoking controls (Eensoo et al., 2004
), suggesting that smoking is not a confounding factor. This result is also in accordance with the primate study by Fahlke et al. (2002)
.
In conclusion, significant differences between the drunk drivers and controls in the pattern of alcohol-related problems, frequency of using strong and light alcoholic drinks during the previous year, safety-belt use, smoking, paying for parking, dysfunctional impulsivity, platelet MAO activity, age and alcohol consumption, suggest that drunk driving is a result of a combination of various behavioural, biological and personality-related risk factors.
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ACKNOWLEDGEMENTS |
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REFERENCES |
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Begg, D. J., Langley, J. D. and Stephenson, S. (2003) Identifying factors that predict persistent driving after drinking, and driving after using cannabis among young adults. Accident Analysis and Prevention 35, 669675.[CrossRef][ISI][Medline]
Cherpitel, C. J. and Tam, T. W. (2000) Variables associated with DUI offender status among whites and Mexican Americans. Journal of Studies on Alcohol 61, 698703.[ISI][Medline]
Cloninger, C. R., Sigvardsson, S. and Bohman M. (1988) Childhood personality predicts alcohol abuse in young adults. Alcoholism: Clinical and Experimental Research 12, 494505.[ISI][Medline]
Cooper, P. J., Pinili, M. and Chen, W. (1995) An examination of the crash involvement rates of novice drivers aged 16 to 55. Accident Analysis and Prevention 27, 89104.[CrossRef][ISI][Medline]
Costa, P. T. Jr and McCrae, R. R. (1989) The NEO-PI/NEO-FFI Manual Supplement. Psychological Assessment Resources, Odessa, FL.
Del Rio, M. C., Gonzalez-Luque, J. C. and Alvarez, F. J. (2001) Alcohol-related problems and fitness to drive. Alcohol and Alcoholism 36, 256261.
Dickman, S. J. (1990) Functional and dysfunctional impulsivity: personality and cognitive correlates. Journal of Personality and Social Psychology 58, 95102.[CrossRef][ISI][Medline]
Eensoo, D., Paaver, M., Pulver, A. et al. (2004) Low platelet MAO activity associated with high dysfunctional impulsivity and antisocial behavior: evidence from drunk drivers. Psychopharmacology 172, 356358.[CrossRef][ISI][Medline]
European Transport Safety Council (2001) Priorities for EU Motor Vehicle Safety Design. European Transport Safety Council, Brussels.
Eysenck, S. B. G., Pearson, P. R., Easting, G. et al. (1985) Age norms for impulsiveness, venturesomenes and empathy in adults. Personality and Individual Differences 6, 613619.[CrossRef][ISI]
Fahlke, C., Garpenstrand, H., Oreland, L. et al. (2002) Platelet monoamine oxidase activity in a nonhuman primate model of type 2 excessive alcohol consumption. American Journal of Psychiatry 159, 21072109.
Fowler, C. J., von Knorring, L. and Oreland, L. (1980) Platelet monoamine oxidase activity in sensation seekers. Psychiatry Research 3, 273279.[CrossRef][ISI][Medline]
Golias, I. and Karlaftis, M. G. (2002) An international comparative study of self-reported driver behavior. Transportation Research Part F 4, 243256.
Grunewald, P. J., Mitchell, P. R. and Treno, A. J. (1996) Drinking and driving: drinking patterns and drinking problems. Addiction 91, 16371649.[CrossRef][ISI][Medline]
Hallman, J., Oreland, L., Edman, G. et al. (1987) Thrombocyte monoamine oxidase activity and personality traits in women with severe premenstrual syndrome. Acta Psychiatrica Scandinavica 76, 225234.[ISI][Medline]
Harro, M., Eensoo, D., Kiive, E. et al. (2001) Platelet monoamine oxidase in healthy 9- and 15-years old children: the effect of gender, smoking and puberty. Progress in Neuro-Psychopharmacology and Biological Psychiatry 25, 14971511.[CrossRef][ISI][Medline]
Hilakivi, I., Veilahti, J., Asplund, P. et al. (1989) A sixteen-factor personality test for predicting automobile driving accidents of young drivers. Accident Analysis and Prevention 21, 413418.[CrossRef][ISI][Medline]
Iversen, H. and Rundmo, T. (2002) Personality, risky driving and accident involvement among Norwegian drivers. Personality and Individual Differences 33, 12511263.[CrossRef][ISI]
Johnson, F. W., Gruenewald, P. J. and Treno, A. J. (1998) Age-related differences in risks of drinking and driving in gender and ethnic groups. Alcoholism: Clinical and Experimental Research 22, 20132022.[ISI][Medline]
Jonah, B. A. (1997) Sensation seeking and risky driving: a review and synthesis of the literature. Accident Analysis and Prevention 29, 651665.[CrossRef][ISI][Medline]
Kayser, R. E., Schippers, G. M. and Van Der Staak, C. P. (1995) Evaluation of a Dutch educational Driving While Intoxicated (DWI) prevention program for driving schools. Journal of Drug Education 25, 379393.[ISI][Medline]
Oreland, L. (2004) Platelet monoamine oxidase, personality and alcoholism: the rise, fall and resurrection. NeuroToxicology 25, 7989.[CrossRef][ISI][Medline]
von Knorring, L., Oreland, L. and Winblad, B. (1984) Personality traits related to monoamine oxidase activity in platelets. Psychiatry Research 12, 1126.[CrossRef][ISI][Medline]
von Knorring, L. and Oreland, L. (1996) Platelet MAO activity in type1/type2 alcoholics. Alcoholism: Clinical and Experimental Research 20, 224A230A.[Medline]
Whitfield, J. B., Pang, D., Bucholz, K. K. et al. (2000) Monoamine oxidase: associations with alcohol dependence, smoking and other measures of psychopathology. Psychological Medicine 30, 443454.[CrossRef][ISI][Medline]
Wilson, R. J. and Jonah, B. A. (1985) Identifying impaired drivers among the general driving population. Journal of Studies on Alcohol 46, 531537.[ISI][Medline]
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