Personality correlates of platelet monoamine oxidase (MAO) activity in female and male subjects

Associations between platelet monoamine oxidase (MAO) activity and scale scores from the Eysenck Personality Questionnaire, the Impulsiveness-Venturesomeness-Empathy inventory and the Karolinska Scales of Personality were studied in 32 female and 29 male students (age range 17-19 years). There 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 sensation seeking-related Monotony avoidance scale, and the Indirect Aggression scale for both female and male low MAO activity groups.     

Thrombocyte monoamine oxidase activity and personality traits in women with severe premenstrual syndrome

Women with premenstrual syndrome (PMS) of such severity that they actively had sought medical attention for their symptoms were compared with healthy female students with regard to platelet MAO activity and temperamental correlates by means of the Karolinska Scales of Personality (KSP), scales from the Eysenck Personality Questionnaire (EPQ) and Eysenck's IVE inventory. The women with PMS were divided into two groups; irritability and depression as predominating symptom. No variation in platelet MAO was found during the menstrual cycle, either in patients or in controls. Both PMS groups had significantly lower platelet MAO activity than the controls. There was no difference between the two groups with PMS. Also with regard to personality traits there were considerable differences between the females with PMS and the controls. There were few differences between the two groups of PMS patients. Thus, the patients scored significantly higher as regards somatic anxiety, muscular tension, indirect aggression, verbal aggression and neuroticism and lower as regards socialization than the controls.     

Platelet MAO activity and personality characteristics

Low levels of platelet monoamine oxidase have been found in schizophrenic and bipolar depressive patients. The enzyme activity seems to correlate negatively with certain personality traits (social activity, sensation seeking, hypomania, positive affect and monotony avoidance) which are correlated to some extent with the score “extraversion” from the Eysenck Personality Questionnaire (EPQ). The present study was carried out in an attempt to investigate further the possible correlation between platelet MAO activity and the personality traits measured by the EPQ. 41 schizophrenic patients and 20 healthy probands were blindly examined for platelet MAO activity and personality characteristics. The enzyme activity was found to correlate negatively with the extra-version score in patients and healthy probands, which is in agreement with the data from other studies. This correlation is discussed and a hypothesis suggested.     

Relationships between attempted suicide, temperamental vulnerability, and violent criminality in a Swedish forensic psychiatric population.

The relationship between suicide attempts and different vulnerability factors was investigated in 61 male subjects during forensic psychiatric examination. Personality traits and psychopathy were determined by means of the Karolinska Scales of Personality (KSP) and the Psychopathy Checklist-Revised (PCL-R). Clinical diagnoses were determined by the use of Structured Clinical Interview for DSM-III-R (SCID). Platelet monoamine oxidase (MAO) activity was investigated in 58 subjects.Suicide attempters had extremely low socialization and high impulsive aggression. This was independent of a history of repeatedly criminal violence or not. They had higher PCL-R scores and lower levels of platelet MAO activity than non-attempters. No relationship was found between suicide attempts and repeated violent criminality. However, among the subjects with repeated criminal violence there was a highly significant difference between suicide attempters and non-attempters, indicating different personality profiles in violent offenders with and without suicidal behavior. Suicidal behavior was significantly associated with borderline personality disorder, but not with any other single DSM-III-R disorder. The results show a far more severe personality disturbance in suicide attempters than in other violent patients in this type of population. Suicidal behavior should therefore be evaluated and treated per se.     

Influence of personality traits on neuropsychological test performance in toxic encephalopathy cases and healthy referent subjects

The relationship between personality traits and cognitive performance was studied in two groups: men with symptoms and neuropsychological test results compatible with toxic encephalopathy (TE) and demographically similar healthy men (N=57 per group). Personality traits were assessed with the Karolinska Scales of Personality (KSP). The neuropsychological examination included 13 tests covering various functional domains. The TE group displayed elevated scores on all three KSP anxiety scales as well as an elevated impulsiveness score. Furthermore, the TE group had a lower score on the socialization scale than did the referent group. Different relationships between personality dispositions and cognitive functioning emerged in the two groups. Within the referent group the highest correlations were observed between KSP anxiety and socialization scale scores and reaction times measures. This pattern did not appear in the TE group; instead, divergent and a few weak relationships emerged. These relationships involved correlations between the KSP monotony avoidance score and some motor speed scores. By dividing the referent group into low anxiety and high anxiety subgroups on the basis of the multi-component anxiety scale score, it was shown that the test scores in the high anxiety subgroup mostly were indistinguishable from the scores in the TE group. In contrast, the low anxiety group had higher test scores than the TE group in 8 of the 13 tests. In conclusion, the expected relationship between anxiety and cognitive vigilance is absent in TE cases. This indicates that the neuropsychological performance decrement in TE cases is not primarily related to elevated mental distress, but is probably dominated by the effects of organic brain impairment. Thus, in TE cases low neuropsychological test scores should not be regarded as a consequence of emotional symptoms. Furthermore, personality traits may be considered as potential confounders even if traditional matching by demographic criteria has been successfully implemented.     

Low platelet monoamine oxidase and sensation seeking in males: an established relationship?

A significant negative correlation between platelet monoamine oxidase (MAO) activity, a stable peripheral enzyme measure under genetic control, and sensation seeking, as measured using the Zuckerman Sensation Seeking Scale (SSS), has been reported for male subjects in several studies. As tobacco smoking has been related to both these measures, in the present study correlations were calculated among smoking and non-smoking male university students. Platelet MAO activity was negatively correlated with the Disinhibition and Total scales of the SSS. These correlations were not significantly different in smokers and non-smokers. The results are discussed in terms of recent evidence of reduced platelet MAO activity in psychiatric patients.     

Platelet monoamine oxidase activity and evoked response as predictors of anxiety and depression derived from the content analysis of speech

Platelet MAO activity has been reported by several investigators to differentiate schizophrenia, schizophrenia related depressive disorders, alcoholism, unipolar and bipolar depression from normal controls. Evoked potentials likewise have differentiated schizophrenic and affective patients. However, the precise relationship between MAO activity, evoked potentials (EP), and psychiatric illness has not been clarified. A possible association between psychopathology and high MAO activity/EP reducing and low MAO activity/EP augmenting has been reported. Such a bidirectionality further confounds results. This study was undertaken to determine the association of psychopathological dimensions found in a group of subjects whose platelet MAO activity and evoked responses were obtained two years earlier. Utilizing the Gottschalk-Gleser verbal behavior scales of Anxiety, Depression, Social Alienation-Personal Disorganization and Cognitive Impairment a significant correlation was revealed between low platelet MAO activity and high Total Anxiety scale and Shame Anxiety subscale scores. Additionally, a significant correlation was demonstrated between reducing evoked potentials and elevated Death Anxiety, Somatic Concerns, and Total Death and Mutilation Depression subscales scores, combined and separately. Furthermore, a significant positive correlation was found between augmenting evoked potentials and Overt Hostility Outward scores. No significant correlations were demonstrated between platelet MAO activity or evoked potentials and Social Alienation-Personal Disorganization or Cognitive Impairment scores. These findings lend support to the position that biological markers may predict predispositions to anxiety and depression.     

Personality traits and platelet monoamine oxidase activity in a Swedish male criminal population

BACKGROUND: A Swedish male criminal population was grouped into personality disorder subgroups and investigated with regard to personality traits and platelet monoamine oxidase (MAO) activity. The main aim of the study was to examine the possibility of a risk factor combination by having low platelet MAO activity as well as belonging to a certain diagnostic DSM-IV axis I (drug abuse in the present series) and/or II subgroup. METHODS: Personality disorders were grouped into clusters according to the cluster system used in DSM-IV axis II. The prisoners were grouped into five subgroups and each subject completed the Karolinska Scales of Personality self-report questionnaire. The comparison group for the personality data comprised 51 non-criminal males from a longitudinal Swedish project. Platelet MAO activity was assessed for the criminals as well as for a control group including 60 non-criminal healthy male Caucasians. For testing the existence of syndromes, a configuration frequency analysis (CFA) was used. RESULTS: The results showed low scores on the socialisation and high scores on the sensation seeking-related traits impulsiveness and monotony avoidance, and the somatic anxiety-related muscular tension in the criminals with any DSM-IV mental disorder, however most markedly in cluster AB and cluster B subjects. In addition, cluster AB subjects had significantly lower platelet MAO activity than controls. Two significant 'types' were found among the criminals: one was characterised by low platelet MAO activity, cluster B personality diagnosis as well as drug abuse disorder diagnosis; and the other by a pattern of normal platelet MAO activity, no cluster B personality disorder and no drug abuse disorder diagnosis. CONCLUSION: The aggregation of certain risk factors in the same individual has been shown to contribute to the development of criminal behaviour.     

Personality traits and platelet MAO activity in alcohol and drug abusing teenage boys

The aim of this study has been to investigate whether teenage boys with mixed drug abuse differ from those with pure alcohol abuse as concerns personality traits and platelet monoamine oxidase activity. The series included 1129 consecutive 18-year-old males called to the Enlistment Center in the northern part of Sweden. A special inventory was constructed based on Zuckerman Sensation Seeking Scale (SSS), Eysenck's Personality Inventory (EPI), the Karolinska Scales of Personality (KSP) and questions about alcohol and drug consumption. The subjects with mixed drug abuse (n = 96) had high scores in the two subscales of SSS and KSP related to ability to stand boredom, high scores in both subscales of EPI and KSP related to impulsivity, high scores in Thrill and Adventure Seeking (TAS) and Experience Seeking (ES) of SSS as well as low platelet monoamine oxidase activity. The males with pure alcohol abuse (n = 33) also showed signs of monotony avoidance and impulsivity, but this type of abuse was not clearly related to low platelet monoamine oxidase activity and not to the aspects of curiosity included in the SSS such as TAS and ES. These findings are consistent with the picture earlier found as concerns "Type II" alcoholism which has an early onset, is genetically transmitted, is associated with mixed drug abuse and social complications.     

Psychological correlates of monoamine oxidase activity in normals

This study replicates and extends earlier work by finding that low levels of platelet monoamine oxidase (MAO) activity correlate with sensation seeking, high ego strength, positive affect, and high leisure time activity levels, somewhat similar psychological correlates also being found for plasma amine oxidase activity. Although there are several ways in which a schizophrenia/MAO relationship may exist and still be congruent with the present data, these results pose difficulties for theories which link low MAO activity levels specifically to schizophrenia. Nothing in the present findings, however, is incongruent with the possibility of an association between low platelet MAO activity and bipolar affective disorder.     

Mental and personality disorders as well as personality traits in a Swedish male criminal population

The study describes personality traits and the presence of personality disorders and mental disorders in a consecutive series of 130 male prisoners in Swedish jails sentenced for serious criminality. The investigation included a psychiatric examination by means of the Structured Clinical Interview (SCID) as well as information taken from criminal records. Personality assessments were made by means of self-report questionnaires, the Karolinska Scales of Personality (KSP) and the DSM-IV and ICD-10 Personality Disorder Questionnaire (DIP-Q). The most common mental disorders were alcohol and drug abuse/dependence, which were present in 55% of the subjects. Personality disorders, too, were common, being present in 56% of the subjects. In the KSP, high scores were found in scales related to impulsiveness, sensation-seeking, nervous tension and distress, cognitive-social anxiety, hostility and aggression. Very low scores were found in the Socialization scale, reflecting a high degree of psychopathy-related personality traits. Despite the high morbidity, the global level of functioning was unexpectedly high, 66 according to GAF. The male prisoners sentenced for heavy criminality had a high degree of both mental disorders and personality disorders. Furthermore, psychopathy-related personality traits were common.     

Psychopathy,platelet MAO activity and criminality among former juvenile delinquents

Psychopathy-related personality traits as well as platelet monoamine oxidase (MAO) activity and criminality from the age of 15 years were studied in a group of 68 male former juvenile delinquents and 32 control subjects. The former juvenile delinquents registered for crime as adults were found to have higher Psychopathy Check List (PCL) scores and lower platelet MA0 activity than either juvenile delinquents who were not registered criminals from the age of 15 years or non-criminal controls. Although PCL scores and platelet MAO activity were unrelated, a configural frequency analysis showed a significant interaction. Individuals with PCL scores, low platelet MAO activity and persistent criminal behaviour constituted a significant ‘type’. Among the 27 former juvenile delinquents who developed persistent criminality, 21 subjects (78%) had PCL scores greater than 0 and low platelet MAO activity, while none of these persistent criminals were characterized by a combination of zero PCL score and high platelet MAO activity.     

Changes in some personality traits after recovery from alcohol dependence/abuse, anxiety and depression--results of a 5-year follow-up in a general population sample of women

The aim of this study was to analyse stability of and change in personality traits in a general population sample of women over 5 years. Specific questions were how personality traits changed after a first episode of alcohol dependence/abuse (ADA), anxiety or depression disorders and after remission of an episode. The study was based on data from a longitudinal general population-based survey titled, "Women and alcohol in G?teborg (WAG)". A total of 641 women were interviewed in 1990 or 1995 and re-interviewed after 5 years. Personality traits were assessed with the Karolinska Scales of Personality (KSP) and lifetime psychiatric diagnoses given according to the Diagnostic and Statistical Manual of Mental Disorders, 3rd revised edition (DSM-III-R). Mean T-scores (KSP) for the general population sample were stable between initial assessment and follow-up 5 years later. Correlations between assessments were high for most KSP scores, indicating high individual stability. For women with resolved ADA, KSP scores were normalized to five scales at the follow-up assessment: somatic anxiety, muscular tension, monotony avoidance, social desirability and irritability. Women who recovered from anxiety disorders during the follow-up had decreased scores in somatic anxiety and muscular tension and increased scores in verbal aggression. Women who developed ADA during follow-up had increased scores on the scales impulsiveness and verbal aggression. Women who developed depression during follow-up had increased monotony avoidance. Personality traits were generally stable in this adult female population but some personality traits changed in association with changes in psychiatric disorders. This knowledge could be useful in evaluation of treatment needs and treatment outcome.     

Platelet monoamine oxidase activity and psychometric correlates in male violent offenders imprisoned for homicide or other violent acts

Violent behavior has been associated with certain personality traits like poor impulse control, sensation seeking, and monotony avoidance, which predispose to increased risk for violent acts. Low platelet monoamine oxidase (MAO) activity has been found in subjects with such traits, as well as in imprisoned violent offenders. On the other hand, cigarette smoking is expected to inhibit MAO activity. We assessed impulse control, lifetime history of aggression, suicide risk, as well as platelet MAO activity in 82 male offenders (mean age 33.0±10.7 years) imprisoned for homicide or other violent acts, and in 54 control male subjects (mean age 35.1 ± 6.6 years). General psychopathology was assessed by the Hopkins Symptom Check List (SCL–90) questionnaire. A high rate of smoking (89 %),significantly higher than controls (63 %), was observed in offenders, but there were no differences in MAO activities among nonsmokers, moderate, or heavy smokers in either group. Offenders showed significantly higher scores in Impulse Control, Past Feelings and Acts of Violence, Suicide Risk and SCL–90 scales. Offenders who had committed other violent acts than homicide had higher scores in the three psychometric scales and in the Depression, Obsessive–Compulsive, Hostility, and Anxiety subscales of the SCL– 90, than offenders who had committed homicide. Platelet MAO activity was significantly lower (p = 0.01) in the offenders group (38.1 ± 14.4) compared to controls (44.7±15.2). The difference could not be attributed to smoking, and seems to be related to personality traits and behaviors that characterize the offenders group.     

Personality traits in patients with idiopathic pain disorder

In the present study, patients with idiopathic pain syndromes have been compared to healthy volunteers, patients with neurogenic pain syndromes and depressed patients as concerns stable personality traits. The personality traits were assessed by means of the Karolinska Scales of Personality (KSP). Patients with idiopathic pain syndromes were found to have high scores on scales measuring Muscular tension, Social desirability, Psychasthenia and Socialization. They had also high scores on the Inhibition of aggression factor. They had low scores on Impulsivity, Monotony avoidance, Indirect aggression, Verbal aggression and Suspicion. As compared to depressed patients, the pain patients were much more controlled, with higher scores on Socialization and Social desirability scales and like depressed patients with a tendency to inhibit aggression. Thus, as compared to depressed patients, the pain patients had less open anxiety but the same degree of muscular tension.     

Personality traits in social phobia.

The purpose was to assess personality traits in subjects with a DSM-IV diagnosis of social phobia. Thirty-two subjects were administered the Structured Clinical Interview for DSM-IV for Axes I and II disorders (SCID I and II). Personality traits were assessed by means of the Karolinska Scales of Personality (KSP). Current and lifetime axis I co-morbidity was diagnosed in 28% and 53% of the subjects, respectively. In total, 59% had at least one personality disorder and 47% were diagnosed with an avoidant personality disorder. The social phobics scored significantly higher than a Swedish normative sample on the KSP measuring anxiety proneness, irritability, detachment, and indirect aggression but lower on the scales for socialisation and social desirability. The presence as compared to absence of avoidant personality disorder in the social phobics was associated with significantly higher psychic anxiety and inhibition of aggression. In addition, symptom severity was higher in social phobics with an avoidant personality disorder. Generally, the results support the view that social phobia and avoidant personality disorder reflect different aspects of a social anxiety spectrum.     

Comorbidity between obsessive-compulsive disorder (OCD) and personality disorders

The aims of the present study were to examine the frequency of personality disorders in 36 patients with obsessive-compulsive disorder (OCD), and to investigate whether patients with a coexisting personality disorder could be characterized by certain personality traits assessed by means of the Karolinska Scales of Personality (KSP). In total, 27 (75%) of the OCD patients fulfilled the DSM-III-R criteria for a personality disorder, and 13 patients (36%) had an obsessive-compulsive personality disorder. Subjects with a comorbid personality disorder had significantly higher scores on most of the KSP scales, including all anxiety scales, as well as scales measuring indirect aggression, irritability, guilt and detachment, whereas subjects without personality disorders did not differ significantly from healthy controls with regard to personality traits.     

Enzymes related to biogenic amine metabololism and personality charateristics in depressed patients

Levels of the activity of enzyme systems involved in the synthesis and metabolism of biogenic amines have been linked in several reports in the literature with various psychopathological conditions and with variations in personality characteristics. In particular, significant negative correlations have been reported between levels of MAO-activity and sensation seeking. In the present study levels of MA0 and DBH-activity were investigated in a series of 30 depressed patients, admitted consecutively, who completed a new personality inventory, the KSP, assumed to measure relatively stable personality traits. Our findings appeared to be consistent with those of earlier authors in that the most pronounced significant (negative) correlation occurred between MAO-activity levels and the monotony avoidance subscale of the KSP. This particular subscale is aimed precisely at measuring thrill-seeking and bears a close relation to the Sensation Seeking Scale used by other authors. In addition a weak positive correlation was found between the same subscale and levels of DBH-activity. Finally a weak negative correlation emerged between levels of MAO and the Guilt subscale of the KSP.     

Platelet monoamine oxidase activity and trace acid levels in plasma of agoraphobic patients

ABSTRACT - Platelet monoamine oxidase activity and plasma trace acid levels in 29 patients classified as agoraphobics was estimated. MAO activity towards p-tyramine and β-phenylethylamine was found to be significantly higher in agoraphobics than in non-agoraphobic depressed patients and healthy controls. In addition plasma p-hydroxyphenylacetic acid levels were low in both agoraphobic and depressed patient groups. All patients were also assessed by Spielberger State Anxiety and the short form of the Beck Depression Inventory scales. No significant correlations could be found between platelet MAO activity or plasma trace acid levels and the psychological scores.     

Correlation of platelet MAO activity with introversion: A study on a German rural population

Platelet monoamine oxidase (MAO) activity and personality characteristics were correlated in a sample of 52 men (37 ± SD 13 years) and 54 women (37 ± SD 15 years) from a rural community. Personality characteristics were measured by using the Freiburger Persönlichkeitsinventar (FPI-A). In the males, weak but significant linear correlations (Pearson product-moment and Spearman rank correlations) were found between platelet MAO activity (p-tyramine and benzylamine as substrates) and the extraversion/introversion dimension. In the females, however, there were no consistent significant correlations between MAO activity and FPI test scores. Comparing the top and bottom 25% of the platelet MAO distribution resulted in a significant difference for the second order factor extraversion in the group of men but not in the group of women. The significant correlation between MAO and introversion could not be attributed to cigarette smoking, food consumption, alcohol, or drugs. In accord with previous biochemical-behavior research, it is suggested that reduced platelet MAO activity may, to some extent, reflect an impulsive personality type.