Impulsivity in everyday life: the role of platelet MAO
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275 References Arato, M., Banki, C.M., Bissette, G. and Nemeroff, C.B. (1989) Elevated CSF CRF in suicide victims. Biol. Psychiatry 25, 355 359. Banki, C.M., Bissette, G., Nemeroff, C.B. and Arato, M. (1988) Corticotropin-releasing factor in depression and suicide. In: M611er, J.H., Schmidtke, A. and Welz, R. (Eds.), Current Issues of Suicidology. Springer, Berlin, pp. 247 251. Charlton, B.G., Wright, C., Leake, A., Ferrier, I.N., Cheetham, S.C. and Katona, C.L.E. (1988) Somatostatin immunoreactivity in postmortem brain from depressed suicides. Arch. Gen. Psychiatry 45, 597 597. Nemeroff, C.B. (1989) Clinical significance of psychoneuroendocrinology in psychiatry: focus on the thyroid and adrenal. J. Clin. Psychiatry 50 (Suppl.), 13 20. Norman, W.H., Brown, W.A., Miller, l.W., Keitner, G.I. and Overholser, J.C. (1990) The dexamethasone suppression test and completed suicide. Acta Psychiatr. Scand. 81, 120 125. Tr/iskman-Bendz, L., Ekman, R., Regnell, G. and Ohmann, R. (1992) HPA-related CSF neuropeptides in suicide attempters. Eur. Neuropsychopharmacol. 2, 99 106. lmpulsivity in everyday life: the role of platelet MAO Juan J. Ldpez-Ibor Jr.*, Jos6 L. Carrasco and Jerdnimo Saiz Ramdn y Cajal Hospital, Alcal~ de Henares University, Madrid. Spain Key words. Impulsive behaviour; Platelet monoamine oxidase Over the last 15 years, impulsivity has been recognized as the pathogenic factor of such clinical entities as drug addictions, eating disorders, trichotillomania, pyromania, pathological gambling and borderline personality disorder. Moreover, impulsivity is thought to underlie other pathological behaviors that did not merit a place in the modern diagnostic manuals, such as suicide and external aggression. The idea of pathological impulsivity has received further validation from neurobiological research. Several serotonergic markers, including CSF 5-HIIA and hormonal response to serotonergic challenges, are reduced in depressed suicide attempters, violent offenders, impulsive arsonists and patients with borderline personality disorder. Platelet MAO is also considered a marker of serotonergic function and MAO levels are correlated with CSF 5-HIIA. Low platelet MAO levels are consistently found in patients with high impulsivity, including suicidal patients, impulsive drug and alcohol addicts and in bulimic patients. However, impulsivity is not only associated with mental pathology. A role for impulsivity in normal behavior has long been recognized as well in all the dimensional models of personality developed in the last 30 years. Impulsiveness is associated with the temperamental features of extraversion, sensation seeking and novelty seeking and multiple studies suggest that it is also associated with a low platelet MAO activity. In this light, it could be assumed that, if pathological impulsive syndromes are associated with a low MAO activity, other behaviors that are not pathological but are also based on unusually increased impulsivity might have a reflection on platelet MAO levels. This may be the case in professional groups that are characterized by risky and sensation seeking activities. Methods To explore this subject, two groups of 16 bullfighters and 29 explosives experts from the Spanish police were investigated in the present study in terms of impulsivity and MAO activity. These healthy-impulsive samples were compared with a group of pathologically impulsive individuals, i.e., 15 DSM-IIIR pathological gamblers, and with a group of 20 healthy and non- impulsive control individuals. All subjects were males between 20 and 45 years old, free of major medical or psychiatric diseases (except pathological gambling) and free of current drug abuse disorders. Subjects underwent a full medical and psychiatric examination and a thorough scrutiny of temperamental traits. Personality assessments were made by the Eysenck Personality Inventory (EPI), the Zuckerman Sensation Seeking Scale (SSS), the "Present position." San Carlos Hospital, Complutense University, Madrid, Spain.
Transcript of Impulsivity in everyday life: the role of platelet MAO
275
References
Arato, M., Banki, C.M., Bissette, G. and Nemeroff, C.B. (1989) Elevated CSF CRF in suicide victims. Biol. Psychiatry 25, 355 359.
Banki, C.M., Bissette, G., Nemeroff, C.B. and Arato, M. (1988) Corticotropin-releasing factor in depression and suicide. In: M611er, J.H., Schmidtke, A. and Welz, R. (Eds.), Current Issues of Suicidology. Springer, Berlin, pp. 247 251.
Charlton, B.G., Wright, C., Leake, A., Ferrier, I.N., Cheetham, S.C. and Katona, C.L.E. (1988) Somatostatin immunoreactivity in postmortem brain from depressed suicides. Arch. Gen. Psychiatry 45, 597 597.
Nemeroff, C.B. (1989) Clinical significance of psychoneuroendocrinology in psychiatry: focus on the thyroid and adrenal. J. Clin. Psychiatry 50 (Suppl.), 13 20.
Norman, W.H., Brown, W.A., Miller, l.W., Keitner, G.I. and Overholser, J.C. (1990) The dexamethasone suppression test and completed suicide. Acta Psychiatr. Scand. 81, 120 125.
Tr/iskman-Bendz, L., Ekman, R., Regnell, G. and Ohmann, R. (1992) HPA-related CSF neuropeptides in suicide attempters. Eur. Neuropsychopharmacol. 2, 99 106.
lmpulsivity in everyday life: the role of platelet MAO
Juan J. Ldpez-Ibor Jr.*, Jos6 L. Carrasco and Jerdnimo Saiz Ramdn y Cajal Hospital, Alcal~ de Henares University, Madrid. Spain
Key words. Impulsive behaviour; Platelet monoamine oxidase
Over the last 15 years, impulsivity has been recognized as the pathogenic factor of such clinical entities as drug addictions, eating disorders, trichotillomania, pyromania, pathological gambling and borderline personality disorder. Moreover, impulsivity is thought to underlie other pathological behaviors that did not merit a place in the modern diagnostic manuals, such as suicide and external aggression.
The idea of pathological impulsivity has received further validation from neurobiological research. Several serotonergic markers, including CSF 5-HIIA and hormonal response to serotonergic challenges, are reduced in depressed suicide attempters, violent offenders, impulsive arsonists and patients with borderline personality disorder.
Platelet MAO is also considered a marker of serotonergic function and MAO levels are correlated with CSF 5-HIIA. Low platelet MAO levels are consistently found in patients with high impulsivity, including suicidal patients, impulsive drug and alcohol addicts and in bulimic patients. However, impulsivity is not only associated with mental pathology. A role for impulsivity in normal behavior has long been recognized as well in all the dimensional models of personality developed in the last 30 years. Impulsiveness is associated with the temperamental features of extraversion, sensation seeking and novelty seeking and multiple studies suggest that it is also associated with a low platelet MAO activity.
In this light, it could be assumed that, if pathological impulsive syndromes are associated with a low MAO activity, other behaviors that are not pathological but are also based on unusually increased impulsivity might have a reflection on platelet MAO levels. This may be the case in professional groups that are characterized by risky and sensation seeking activities.
Methods
To explore this subject, two groups of 16 bullfighters and 29 explosives experts from the Spanish police were investigated in the present study in terms of impulsivity and MAO activity. These healthy-impulsive samples were compared with a group of pathologically impulsive individuals, i.e., 15 DSM-IIIR pathological gamblers, and with a group of 20 healthy and non- impulsive control individuals. All subjects were males between 20 and 45 years old, free of major medical or psychiatric diseases (except pathological gambling) and free of current drug abuse disorders.
Subjects underwent a full medical and psychiatric examination and a thorough scrutiny of temperamental traits. Personality assessments were made by the Eysenck Personality Inventory (EPI), the Zuckerman Sensation Seeking Scale (SSS), the
"Present position." San Carlos Hospital, Complutense University, Madrid, Spain.
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t i+ t i i i
Controls Gamblers Bullfighters 1 Explosives experts
+ p < . O 0 1 ; * p<.01
Fi~. 1. Platelet MAO activity (in nnlol h 10 ~ platclcl,~/.
Cloninger Tridimensional Personality Questionnaire (TPQ) and by the application of self-rated visual analogue scales (0 100) for impulsivity, sensation seeking and extraversion. Platelet MAO activity was determined by an isotopic method using 14C- benzylamine as substrate.
Results
Clinical and temperamental assessments suggested that explosives experts, unexpectedly, were not impulsive or sensation seekers, in concordance with the personnel selection policy of this brigade. Therefore, explosives experts presented no differences on platelet MAO compared to the control group. Bullfighters had the highest scores on sensation seeking and extraversion-impulsivity of all groups. In consonance, they had a significantly lower platelet MAO activity (8 nmol/h/10 ~ platelets, SD 2.1) than controls (9.2, SD 2.0) and explosives experts (10, SD 2.8) (P<0.05). Pathological gamblers had the lowest values of platelet MAO in the whole sample (6.7, SD 1.1: P<0.001) and they scored the highest on the self-rated impulsivity analogue scales and had the highest rates of impulsive associated habits (Fig. 1).
Platelet MAO decrements were much larger in pathological gamblers (30% of the global mean) than in bullfighters (14% of the global mean). In addition, the range of MAO values in bullfighters was similar to that in controls. In gamblers, the range was much smaller, and low MAO levels were present in all the gamblers in the sample.
Conclusions
Results suggest that non-pathological impulsive behaviors, such as bullfighting, may be biologically determined, with low platelet MAO representing a dimensional marker of temperamental traits. On the other hand, in pathological impulsivity, such as pathological gambling, MAO reduction seems to represent a discrete (non-dimensional) pathological dysfunction. probably reflecting alterations in serotonergic activity.
References
Coccaro, E.F., Siever, L.J., Klar, H.M., Maurer, G., Cochrane, K., Cooper, T.B., Mohs, R.C. and Davis, K.L. (199(/) Serotonergic studies in patients with affective and personality disorders: correlates with suicidal and impulsive aggressive behavior. Arch. Gen. Psychiatry 46, 587 599.
Ldpez-lbor Alifio, J.J., Saiz-Ruiz, J. and Perez de los Cobos, J.C. (1985) Biological correlations of suicide and aggressivity in major depression (with melancholia): 5-hydroxyindolacetic acid and cortisol in cerebrospinal fluid, dexamethasone suppression test and therapeutic response to 5-hydroxytryptophan. Neuropsychobiology 14, 67 74.
Ward, P.B., Catts, S.V., Norman, T.R., Burrows, G.D. and McConaghy, N. (1987) Low platelet monoainine oxidase and sensation seeking in males: an established relationship? Acta Psychiatr. Scand. 75, 86--90.
