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Personality and neuropsychological correlates of platelet monoamine oxidase (MAO) activity in female and male subjects
PharmacologicaIResearch Communications, Vol. 20, Supplement IV, 1988
P E R S O N A L I T Y AND N E U R O P S Y C H O L O G I C A L C O R R E L A T E S PLATELET MONOAMINE OXIDASE (MAO) ACTIVITY IN FEMALE AND MALE SUBJECTS
147
OF
1,2B. af Klinteberg, 1,2D. Schalling, 3S.E. Levander and 4L. Oreland
1Dept of Psychiatry and Psychology, Karolinska Inst, Sloekholm. 2Dept of Psychology, Univ. of Stockholm. 3Inst of Psychiatry, Univ. of Trondheim. 4Dept of Pharmacology, Univ. of Uppsala .Key-words: Monoamine oxidase activity, personality inventories, neuropsychological tests, sex, spatial ability Markers of monoamine transmitter systems, i.e., metabolites in the eerebrospinal fluid (CSF), have shown replicable differences between groups of psychiatric patients and healthy controls (/~sberg, Schalling, Tr~iskman-Bendz, & W~igner, 1987). They also show great variations in a sample of normals. This might indicate that deviances in these biological variables could be indicators for vulnerability to psychopathology in normal subjects. Aggressive and disinhibited behaviors have in several studies been associated with low serotonergic activity in the central nervous system (CNS). A more accessible biological marker is the activity of the enzyme monoamine oxidase (MAO) in blood platelets. Platelet MAO activity is assumed to reflect characteristics of the central serotonergic system (Oreland & Shaskan, 1983) and has been associated with personality traits and behaviour in many studies (for a review see Oreland, yon Knorring, & Schalling, 1984). Subjects (mainly male subjects) with low MAO activity levels are reported to be high in sensation seeking, monotony avoidance, and impulsive traits. Such stable personality traits have, in turn, been found to be related to characteristics of cognitive processing. The present study is based on data for male and female high-school students. MAO activity was measured in platelets. Personality inventories (the Eysenck Personality Questionnaire, EPQ, and the Karolinska Scales of Personality, KSP) and computerized neuropsyehological tasks, reaction time (RT) and perceptual maze (PMT) tests, were applied. The aim was to analyze relations between platelet MAO activity and scores from the personality scales and to link the MAO measures to RT and PMT indices of strategy, cerebral lateral organization, and hemispheric activation, which might contribute to the understanding of neuropsychological processes underlying the consistent MAO relationships with personality and sex.
0031-6989/88[201V0147-2/903.00/0
© 1988 The Italian PharmacoiogicalSociety
148
PharmacologicalResearch Communications, VoL 20, Supplement IV, 1988
The main findings were significant negative correlations between MAO activity and extraversion-related scales for male subjects; in the female group the correlations were also negative but nonsignificant. When comparing subgroups with low, intermediate, and high platelet MAO activity subjects, consistent trends were observed in the direction of higher scores in the impulsivity scales, the KSP Monotony avoidance scale, and the KSP Indirect Aggression scale fox- both female and male low MAO activity groups. In the male group, both low and high MAO activities were related to indices of motor "disinhibition". In both male and female subjects low MAO activity was associated with the use of an impulsive-global strategy on the PMT and good spatial skill. In accordance with expectations males were found to have lower platelet MAO activity than females. Among sex differences obtained in the RT and PMT tasks were: (I) males had more response errors for fight-sided (presumably left-hemisphere processed) stimuli in the two-choice visual reaction time tasks; (2) a female tendency toward left-hemisphere activation, regardless of task characteristics; and (3) a male tendency to apply an impulsive-global "right-hemisphere" approach to the tasks and proficiency in spatial skill. It is noteworthy that the present low MAO a(:tivity groups scored high on the sensation seeking-related KSP Monotony avoidance scale, which has been reported to be associated with testosterone (Mattsson, Schalling, Olweus, LOw, & Svensson: 1980). These results are in line with findings of an association between spatial skill and testosterone (Hier & Crowley, 1982). References: ]~sberg, M., Sehalling, D., Trliskrnan-Bendz, L., & W/igner, A. (1987). In: H.Y. Meltzer (ed.), Psychopharmacol.: A third Generation of Progr. (pp. 655-668). New York: Raven Press. Hier, D.B., & Crowley Jr, M.D. (1982). New England J. Med., 306, 1202-1205. Mattsson, A., Schalling, D., Olweus, D., I.,/Sw, H., & Svensson, J. (1980). J. Am. Acad. Child Psychiat., 19, 476-490. Oreland, L., yon Knorring, L., & Sehalling, D. (1984). In: W. Patton, J. Mitchell, & P. Turner (eds.), Proe. IXth Int. Congr. Pharmacol., vol. 2 (pp. 193-202). London: Mac Millan Press. Oreland, L., & Shaskan, E.G. (1983). Trends Pharmaeol. Sci., 4, 339-341.
P E R S O N A L I T Y AND N E U R O P S Y C H O L O G I C A L C O R R E L A T E S PLATELET MONOAMINE OXIDASE (MAO) ACTIVITY IN FEMALE AND MALE SUBJECTS
147
OF
1,2B. af Klinteberg, 1,2D. Schalling, 3S.E. Levander and 4L. Oreland
1Dept of Psychiatry and Psychology, Karolinska Inst, Sloekholm. 2Dept of Psychology, Univ. of Stockholm. 3Inst of Psychiatry, Univ. of Trondheim. 4Dept of Pharmacology, Univ. of Uppsala .Key-words: Monoamine oxidase activity, personality inventories, neuropsychological tests, sex, spatial ability Markers of monoamine transmitter systems, i.e., metabolites in the eerebrospinal fluid (CSF), have shown replicable differences between groups of psychiatric patients and healthy controls (/~sberg, Schalling, Tr~iskman-Bendz, & W~igner, 1987). They also show great variations in a sample of normals. This might indicate that deviances in these biological variables could be indicators for vulnerability to psychopathology in normal subjects. Aggressive and disinhibited behaviors have in several studies been associated with low serotonergic activity in the central nervous system (CNS). A more accessible biological marker is the activity of the enzyme monoamine oxidase (MAO) in blood platelets. Platelet MAO activity is assumed to reflect characteristics of the central serotonergic system (Oreland & Shaskan, 1983) and has been associated with personality traits and behaviour in many studies (for a review see Oreland, yon Knorring, & Schalling, 1984). Subjects (mainly male subjects) with low MAO activity levels are reported to be high in sensation seeking, monotony avoidance, and impulsive traits. Such stable personality traits have, in turn, been found to be related to characteristics of cognitive processing. The present study is based on data for male and female high-school students. MAO activity was measured in platelets. Personality inventories (the Eysenck Personality Questionnaire, EPQ, and the Karolinska Scales of Personality, KSP) and computerized neuropsyehological tasks, reaction time (RT) and perceptual maze (PMT) tests, were applied. The aim was to analyze relations between platelet MAO activity and scores from the personality scales and to link the MAO measures to RT and PMT indices of strategy, cerebral lateral organization, and hemispheric activation, which might contribute to the understanding of neuropsychological processes underlying the consistent MAO relationships with personality and sex.
0031-6989/88[201V0147-2/903.00/0
© 1988 The Italian PharmacoiogicalSociety
148
PharmacologicalResearch Communications, VoL 20, Supplement IV, 1988
The main findings were significant negative correlations between MAO activity and extraversion-related scales for male subjects; in the female group the correlations were also negative but nonsignificant. When comparing subgroups with low, intermediate, and high platelet MAO activity subjects, consistent trends were observed in the direction of higher scores in the impulsivity scales, the KSP Monotony avoidance scale, and the KSP Indirect Aggression scale fox- both female and male low MAO activity groups. In the male group, both low and high MAO activities were related to indices of motor "disinhibition". In both male and female subjects low MAO activity was associated with the use of an impulsive-global strategy on the PMT and good spatial skill. In accordance with expectations males were found to have lower platelet MAO activity than females. Among sex differences obtained in the RT and PMT tasks were: (I) males had more response errors for fight-sided (presumably left-hemisphere processed) stimuli in the two-choice visual reaction time tasks; (2) a female tendency toward left-hemisphere activation, regardless of task characteristics; and (3) a male tendency to apply an impulsive-global "right-hemisphere" approach to the tasks and proficiency in spatial skill. It is noteworthy that the present low MAO a(:tivity groups scored high on the sensation seeking-related KSP Monotony avoidance scale, which has been reported to be associated with testosterone (Mattsson, Schalling, Olweus, LOw, & Svensson: 1980). These results are in line with findings of an association between spatial skill and testosterone (Hier & Crowley, 1982). References: ]~sberg, M., Sehalling, D., Trliskrnan-Bendz, L., & W/igner, A. (1987). In: H.Y. Meltzer (ed.), Psychopharmacol.: A third Generation of Progr. (pp. 655-668). New York: Raven Press. Hier, D.B., & Crowley Jr, M.D. (1982). New England J. Med., 306, 1202-1205. Mattsson, A., Schalling, D., Olweus, D., I.,/Sw, H., & Svensson, J. (1980). J. Am. Acad. Child Psychiat., 19, 476-490. Oreland, L., yon Knorring, L., & Sehalling, D. (1984). In: W. Patton, J. Mitchell, & P. Turner (eds.), Proe. IXth Int. Congr. Pharmacol., vol. 2 (pp. 193-202). London: Mac Millan Press. Oreland, L., & Shaskan, E.G. (1983). Trends Pharmaeol. Sci., 4, 339-341.