Platelet monoamine oxidase in alcoholism

The Association between a MAOB Variable Number Tandem Repeat Polymorphism and Cocaine and Opiate Addictions in Polyconsumers

Genetic analysis of the association between alcohol, cocaine, and opiate addiction and variable number tandem repeat (VNTR) polymorphisms in monoamine oxidase B (MAOB) and serotonergic 5-hydroxytryptamine (serotonin) receptor 1B and 2C (HTR1B 21 and HTR2C) pathway genes was performed in a sample of 302 polyconsumers. Our genetic association analysis revealed a significant association between a 184 base pair (bp) VNTR polymorphism in the MAOB gene and addiction to cocaine and opiates. This work highlights new genetic marker associations in cocaine and opiate polyconsumer addictions. These data help to clarify and quantify the complex role of genetics in addictive disorders, as well as their future contribution to the prevention (genetic counselling), diagnosis (genetic diagnosis of vulnerability), and treatment (pharmacogenomics) of these disorders.

Monoamine oxidase A variants are associated with heavy betel quid use

Few studies have investigated whether genetic abnormalities predispose individuals to heavy betel quid (BQ) use. One of the major ingredients of BQ, arecoline, is known to affect the expression of monoamine oxidase A (MAO-A). We investigated the extent to which arecoline inhibits MAO-A expression and the role of MAO-A polymorphisms in BQ use in Taiwanese aborigines. Cytotoxicity assays, microarrays and quantitative reverse transcriptase-polymerase chain reaction were used to examine the effects of arecoline and areca nut extract (ANE) on cell viability and MAO-A expression in neuroblastoma SH-SY5Y cells. After identifying the effective concentrations of arecoline and ANE in vitro, we examined the in vivo effects of these compounds using a rat model system. Our results indicate that arecoline and ANE inhibit MAO-A expression both in vitro and in vivo. In addition, we examined the correlation between plasma MAO-A activity and cumulative exposure to BQ in humans. We recruited 1307 aborigines from a large-scale community-based survey to determine whether MAO-A variants were associated with high BQ use and a preference for use with smoking or alcohol and whether gender bias existed. MAO-A expression was significantly downregulated by arecoline and ANE at 100-200 µg/ml and in rat whole brains on days 30 and 45. MAO-A activity levels in human plasma were positively correlated with the extent of BQ exposure, and individuals with at-risk alleles exhibited lower activity, although this result did not reach statistical significance. We found two single nucleotide polymorphism (SNPs) in aboriginal males [rs2283725, odds ratio (OR) = 2.04; rs5953210, OR = 2.03] and females (rs2283725, OR = 1.54; rs5953210, OR = 1.59) that were associated with heavy BQ use. Those individuals carrying at-risk alleles who drank alcohol were twice as likely to be heavy BQ users. However, the effects of these SNPs on BQ use were significant even after controlling for alcohol use. Our results suggest that two specific loci may confer a susceptibility to BQ abuse and affect MAO-A enzymatic activity.

Neuropsychological function and platelet monoamine oxidase activity levels in type I alcoholic patients

AIMS

To explore neuropsychological function in two differentiated patterns of platelet monoamine oxidase B (MAO B) activity in alcoholic patients.

METHODS

Neuropsychological examination and platelet MAO B activity extracted from blood were collected from 42 alcohol-dependent patients recruited in the alcoholism unit (NETER) of the Psychiatric Service of Santa Maria University Hospital.

RESULTS

Alcoholics presented significantly low levels of platelet MAO B activity, when compared with control subjects; platelet MAO B activity in alcoholics classified as "under average subgroup" showed significant lower scores in the Raven Progressive Matrix and higher scores in hostility dimension, when compared with platelet MAO B activity in "above average subgroup."

CONCLUSIONS

Results suggested platelet MAO B as a trait marker also to type I alcohol-dependent patients and the two observed associations between platelet MAO B activity with neurocognitive measures of executive functions (nonverbal reasoning) and psychopathological dimension such as hostility may support the notion about the effect of platelet MAO B activity in the further development of an impulsive cognitive style.

Personality Characteristics as Risk Indications of Alcohol Use and Violent Behavior in Male and Female Adolescents

Abstract. The present study focused on personality characteristics in adolescent boys (n = 414) and girls (n = 552) in 8th grade with self-reported violent behavior and risky alcohol use. Adolescents with indications of violent behavior and/or risky alcohol use, compared to others, were generally more impulsive, had a stronger need for change and action, were less adjusted and socially conforming, as well as more aggressive. The findings pointed toward a clustering of problem behaviors. Furthermore, adolescents with a combination of violent behavior and alcohol use had more pronounced personality scores than subjects who reported only one of these behaviors. The main finding was that among girls these behaviors appeared to be associated with more deviant levels of the personality characteristics in focus.

Platelet monoamine oxidase in healthy 9- and 15-years old children: the effect of gender, smoking and puberty

1. The effect of gender, smoking and pubertal development on platelet monoamine oxidase (MAO) activity was described in a randomly selected, large sample of 9- and 15-years old healthy children. 2. Platelet MAO activity was measured in 1129 children by a radioenzymatic method with beta-phenylethylamine as the substrate. Smoking habits were reported in an anonymous questionnaire. Pubertal status was assessed visually using Tanner's stages. 3. Boys, younger children and smokers had significantly lower platelet MAO activity than girls, older children and non-smokers, respectively. Girls in Tanner's stage V for breast and pubic hair development had significantly lower MAO than girls in stage IV. 4. Differences in gender, age, pubertal status and smoking habits must be taken into account if the relationship between platelet MAO activity, personality and psychiatric disorders is studied in children.

Platelet monoamine oxidase activity in alcoholics with and without a family history of alcoholism

A number of studies point at platelet monoamine oxidase (MAO) activity being reduced in alcoholics with a family history of drinking, this being a possible vulnerability marker for alcoholism. To test this hypothesis, we examined a group of recently detoxified alcoholics with high (n = 25) and low genetic loading for alcoholism (n = 28) and a group of healthy controls (n = 21). Clinical assessments were made using the SCID II interview for psychiatric disorders, the Family History Assessment Module and the Semi-Structural Assessment of Genetics in Alcoholism, a questionnaire especially designed for genetic studies. Platelet MAO activity with and without ethanol stimulation and the percentage of MAO activity with ethanol did not differ between groups. The only significant difference was a lower inhibition of MAO activity with ethanol in alcoholics both with and without a family history compared to controls. In patients with antisocial personality traits, platelet MAO activity was also not found to be different from other alcoholics. Our findings question the hypothesis of reduced platelet MAO activity to be a possible vulnerability marker for alcoholism.

Possible linkage of alcoholism, monoamine oxidase activity and P300 amplitude to markers on chromosome 12q24

Multipoint linkage analysis was used to screen for evidence of linkage between alcoholism and five alcoholism-related quantitative traits. The results suggest that a susceptibility locus that influences monoamine oxidase activity and P300 amplitude at the Pz lead, and increases the risk of alcohol dependence may be linked to markers in the 12q24 region. Furthermore, the susceptibility for alcoholism may be associated with allele 3 (allele size 144) of D12S392.

The urinary MHPG/creatinine ratio and its relationship to platelet monoamine oxidase activity in abstinent alcoholics

This study was designed to assess the baseline noradrenergic turnover of subgroups of postwithdrawal abstinent alcoholics and healthy controls. The method chosen was an overnight fasting urine sample of the breakdown product of norepinephrine, MHPG, related to urinary creatinine. A comparison was made with platelet monoamine oxidase activity and also within subgroups of the study population. This study found no difference between alcoholics and controls, nor between subgroups of postwithdrawal alcoholics in their level of urinary MHPG corrected for creatinine, and no significant correlation with major subject characteristics or with platelet monoamine oxidase. There was a trend, however, towards a significant correlation with duration of abstinence from alcohol, and there was a correlation with a history of fighting when drinking alcohol, but not with sociopathic traits overall. Within the type 2 alcoholics there was a significant correlation with a history of fighting when drinking and a negative correlation with behavioral tolerance to alcohol. It is possible that only the subset of type 2 alcoholics with certain antisocial characteristics have noradrenergic abnormalities. Although no statistical difference was found between the different groups under study, the information is helpful in increasing understanding of the noradrenergic system in abstinent alcoholics.

Differential Susceptibility to Comorbid Drug Abuse and Violence

Although many psychoactive substances have been associated with violent behavior, only a subgroup manifests excessively aggressive behavior when sober or intoxicated. Theories to explain addictive behaviors in general may directly relate to the specific proclivity to exhibit excessive aggression in this subset of users. Certain personality traits and cognitive deficits coexist in individuals prone to both drug abuse and violence, suggesting a common origin. Because these excessive and compulsive behaviors have been linked with aberrations in the metabolism and activity of the neurotransmitters dopamine and serotonin, their origins may be partly genetic or biological. Alterations in neurotransmitter function influence activities within the brain's reward center to perturb nervous system arousal levels, thereby increasing stimulation-seeking behaviors. Manifestations of these neurobiological aberrations can be measured in physiological and biochemical processes that serve to mediate these behavioral and psychological outcomes.

Platelet monoamine oxidase activity in subgroups of alcoholics and controls: results from the Collaborative Study on the Genetics of Alcoholism

OBJECTIVE

Platelet monoamine oxidase (MAO) B activity levels were evaluated to determine whether low platelet MAO activity is a marker for alcoholism, correlates of alcoholism (e.g., cigarette smoking), or a subtype of alcoholism.

METHODS

Adult women (n = 788) and men (n = 685) participating in the Collaborative Study on the Genetics of Alcoholism study were evaluated with a semistructured interview, and blood samples were obtained for determination of platelet MAO activity using tryptamine (0.1 mM) as substrate. DSM-III-R alcohol-dependent individuals were subgrouped using four currently available methods (e.g., two variations of the type 1/type 2 scheme, primary versus secondary typology, type A/type B dichotomy).

RESULTS

In the overall sample, subjects' gender, cigarette smoking status, and the Collaborative Study on the Genetics of Alcoholism site at which their platelets were prepared explained 22% of the variance in platelet MAO activity levels, and multivariate analysis showed that carrying a broad diagnosis of alcohol dependence did not uniquely explain any additional variance in platelet MAO activity levels. Furthermore, within each of the alcoholic subgrouping methods tested, there were no significant differences in platelet MAO activity for type 1 versus type 2, type A versus type B, or primary versus secondary alcoholics.

CONCLUSIONS

Cigarette smoking and male gender are associated with decreased platelet MAO activity levels. After considering these factors, a diagnosis of alcohol dependence does not predict any additional variance in MAO-B activity. Phenotypes of alcoholics (e.g., type 1 versus type 2, type A versus type B, primary versus secondary) do not differ in platelet MAO activity. The results suggest that decreased platelet MAO activity is not a trait marker of alcoholism or one of its subtypes; but, rather, is a state marker of cigarette smoking.

Platelet MAO activity in subtypes of alcoholics and controls in a homogenous population

The level of platelet monoamine oxidase (MAO) activity has been found to vary between alcoholics and healthy controls and between subtypes of alcoholics, in different populations. This study measured the MAO activity in a group of 46 abstinent alcohol dependent subjects and 22 healthy non-alcoholic controls, male and female, in an ethnically homogenous Irish population. The healthy control subjects had a mean MAO activity of 0.27 pmol/hr/10(5) platelets (+/- SEM 0.03), while the alcoholics overall had a mean activity of 0.34 pmol/hr/10(5) platelets (+/- 0.03) and this difference was not significant, P = 0.2. When the alcoholic group was divided into subtypes of alcoholism, (type 1 and type 2) there was no difference between subtypes of alcoholics nor between each subtype and the controls in their MAO activity. There was no correlation between MAO activity and the age of the subjects, the duration of abstinence from alcohol, the severity of alcoholism, smoking status or the gender of the subjects. These data are discussed in the context of the current literature on alcoholism and platelet MAO in different ethnic populations and the status of platelet MAO as a potential marker for alcoholism.

Biphasic and region-specific MAO-B response to aging in normal human brain

Variations of monoamine oxidases (MAO) A and B were studied during aging in 27 human subjects (age range 17-93 years) in 18 brain structures of temporal cortex, frontal gyrus, hippocampal formation, striatum, cerebellum, and brainstem. [3H]Ro41-1049 and [3H]lazabemide were used as selective radioligands to image and quantify MAO-A and MAO-B respectively by enzyme autoradiography. Postmortem delay or time of tissue storage did not affect MAO-A or MAO-B levels. There was, moreover, no evidence of sexual dimorphism. A marked age-related increase in MAO-B was observed in most structures. This increase started at the age of 50-60 years. Before this age, MAO-B levels were constant in all structures studied. MAO-B-rich senile plaques were observed in some cortical areas but they did not significantly influence the age-related MAO-B increase. Surprisingly, no age-related MAO-B changes were observed in the substantia nigra. In contrast to MAO-B, no clear age-related changes in MAO-A were observed, indicating an independent regulation of the two isoenzymes, also suggested by the cross-correlation analysis of these data.

Platelet monoamine oxidase (MAO) activity and alcoholism: is there a genuine association?

Monoamine oxidase (MAO) is a particle-bound flavoenzyme principally located in the outer mitochondrial membrane, which catalyzes the oxidative deamination of a variety of the amine transmitters in the central nervous system. There have been many reports from different groups around the world over the last 20 years that indicated a lower platelet MAO activity was associated with alcoholism. As there are multiple influences upon measured MAO activity, this article attempts to address each of the issues in turn for potential confounding of the reported association. These issues include: the duration of abstinence from alcohol, the substrate used for analysis, gender issues, association with different subtypes of alcoholics, the influence of other psychopathology, personality traits of alcoholics, the question of smoking, and proposed modes of transmission of MAO activity. The initial promise about MAO activity being a possible marker for alcoholism or a least a genetically predisposed subgroup has receded as the number of negative typology-based studies increases. The failure to account for a major confounding variable, e.g. smoking and other minor but possibly vital confounds in almost all these studies leaves the whole hypothesis open to criticism. However, the possible association between personality traits that might predispose to some if not all substances of addiction to low MAO activity may make it possible to reframe the hypothesized association in the setting of a generalized predisposition to addictions in particular, and to psychopathology in general. Nonetheless the association remains of great interest and may yet yield vital genetic and clinical information.

Genetic markers of alcohol abuse

In this paper, we review the current status of genetic markers for the development of alcohol abuse. Family, twin, half-sibling and adoption studies of alcoholic subjects suggest that the heritability of liability to alcoholism is at least 50%. These findings have fuelled intensive investigation in the fields of neurology, biochemistry, genetics and molecular biology aimed at the identification of markers for the risk of alcoholism. The most promising of these are discussed in detail. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) polymorphisms, specifically the ADH3*1, ADH2*2, and ALDH2*2 genotypes appear to confer a protective effect against alcoholism, most notably in Oriental subjects. Caucasian alcohol abusers and their first-degree relatives exhibit depressed platelet monoamine oxidase activity, the degree of which is greater in Type II than Type I alcoholics. Electrophysiological characteristics of alcoholics and those at risk for developing alcoholism have also been identified, including the reduced amplitude of the event-related brain potential and, after ethanol ingestion, characteristic EEG alpha-wave activity. Lower platelet adenylate cyclase activity is seen in alcoholics compared to controls, presumably as a result of over-expression of an inhibitory G-protein. Markers related to other signal transduction pathways of the central nervous system including the serotoninergic, muscarinic and dopaminergic systems are also discussed. In this group of markers, the putative association between the inheritance of the AI allele of the D2 dopamine receptor and the susceptibility to alcoholism provides the most dramatic illustration of the challenges presently existing in this field of scientific investigation. Current limitations in the definition, diagnosis and classification of alcoholism, the confounding influences of race and gender on association studies, as well as the statistical approach of linkage studies are discussed as they relate to the endeavor to uncover valid genetic markers for the risk of alcoholism.

Serotonin in early-onset alcoholism

This chapter examines current, common schemes to subgroup alcoholics to arrive at relatively homogeneous groups of patients to facilitate psychobiological and molecular genetic studies. Early-onset, male-limited alcoholism is commonly associated with antisocial personality disorder or antisocial behavioral traits. It is often preceded by early-onset aggressiveness, which is followed by conduct disorder. Early-onset alcoholism among men is associated with low central serotonin turnover rate. The data concerning platelet MAO activity and serotonin uptake to platelets among early-onset alcoholics are conflicting. Recent molecular genetic and brain imaging studies on early-onset alcoholics are preliminary but appear very promising.

Monoamine oxidases and alcoholism. II. Studies in alcoholic families

Thirty-five alcoholic families have been studied to investigate the relationship between DNA markers at the monoamine oxidase (MAO) loci and 1) platelet activity levels and 2) alcoholism. A quantitative linkage analysis failed to reveal any evidence that the variation in activity levels cosegregates with the DNA markers. A sib-pair analysis did not reveal a significant excess of MAO haplotype sharing among alcoholic sibs, although the deviation from random sharing was in the direction consistent with an X-linked component. A reanalysis of platelet MAO activity levels in a subset of these families revealed that the lower levels previously found in alcoholics is more likely due to the differences between males and females. Only among males and only when a "broad" definition of alcoholism is used (and MAO activity levels are transformed to normality) does it appear that alcoholics have depressed activities compared to nonalcoholics. Finally, when the confounding due to gender difference is removed, no differences between type I and type II alcoholics are found in these families.

Monoamine oxidases and alcoholism. I. Studies in unrelated alcoholics and normal controls

Low platelet MAO activity has been associated with alcoholism. In order to evaluate the role of MAO genes in susceptibility to alcoholism, we have taken a biochemical and molecular genetic approach. The sample consisted of 133 alcoholic probands who were classified by subtypes of alcoholism and 92 normal controls. For those subjects typed for platelet MAO activity, alcoholics (N = 74) were found not to differ from the non-alcoholics controls (N = 34). Neither was there a significant difference between type I and type II alcoholics or between either subtype and normal controls. However, we do find significant differences between male and female alcoholics, but not between male and female controls. The allele frequency distribution for the MAO-A and MAO-B dinucleotide repeats is different between the alcoholic sample (N = 133) and the normal control sample (N = 92). In a two-way analysis of variance of MAO-B activity as a function of the allelic variation of each marker locus and diagnosis, there is no evidence for mean differences in activity levels for the different alleles. Our findings do not rule out a role for the MAO-B gene in controlling the enzyme activity because the dinucleotide repeats are located in introns.

Platelet monoamine oxidase activity levels in subgroups of alcoholics: diagnostic, temporal, and clinical correlates

Platelet monoamine oxidase (MAO) activity levels were measured in 47 male inpatient alcoholics to determine whether this biological marker might be useful in differentiating subtypes of alcoholics. Of the subgrouping methods tested, only type 2 alcoholics defined by the criteria of Gilligan et al had significantly lower platelet MAO activity than type 1 alcoholics at intake, but this finding was not stable over time in a subset of subjects. Neither separating male veteran alcoholics into either of two other variations of the type 1/type 2 subtypes, nor classifying the sample into primary alcoholics versus primary ASPD with secondary alcoholism categories, yielded significant differences between subgroups. Generally, enzyme activity levels (Vmax) were higher about 10 days after stopping drinking compared to platelet MAO values determined in thrombocytes obtained after approximately 4 weeks abstinence; these levels remained relatively stable 3 months later in a cohort of subjects. Tobacco smoking was significantly negatively correlated to platelet MAO activity levels.

Longitudinal observations of monoamine oxidase B in alcoholics: differentiation of marker characteristics

The marker characteristics of monoamine oxidase B (MAO B) in human platelets were investigated in a clinical study of 59 alcoholics (diagnosed according to the criteria of ICD-10) observed over a period of 6 months. Demographic and family history were obtained by a structured interview, including the substance abuse section of CIDI (Composite International Diagnostic Interview). The patient's personality was assessed by Cloninger's Tridimensional Personality Questionnaire (TPQ). Blood samples were first drawn during chronic intoxication (day of admission to the hospital for detoxication), after short-term abstinence (8 days later), medium-term (3 months later), and long-term abstinence (6 months later). A group of 22 matched healthy nonalcoholics served as controls studied under sober conditions and during acute intoxication (4 hr after ingestion of 1 g ethanol/kg body weight). All platelet samples were investigated with 6 kynuramine concentrations as substrate (fluorometric assay) in the absence and presence of 200 mM ethanol (ETOH) in vitro. MAO B activity was significantly reduced in alcoholics during chronic intoxication (Vmax: 2.70 +/- 0.15 nmol/mg protein) compared with sober (Vmax: 3.25 +/- 0.23 nmol/min/mg protein) and acutely intoxicated controls that turned to normal during abstinence. However, MAO B activity obtained during medium- and long-term abstinence was significantly lowered in patients with high novelty-seeking and impulsiveness scores in the TPQ, a history of suicide attempts, or an alcoholic mother. The affinity of MAO B (Km values) was unchanged in alcoholics at any time investigated. Addition of ETOH in vitro reduced the affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet monoamine oxidase activity in alcoholics, alcoholics with drug dependence, and cocaine addicts

The main objective of this investigation was to study the influence of drug dependence on platelet monoamine oxidase (MAO) activity in the presence and absence of alcoholism. One hundred and thirteen admissions to alcohol and drug treatment facilities participated in the study. Twenty-six met the criteria for alcoholism (group I), seventy-eight subjects were alcohol-/cocaine- and cannabis-dependent (group II), and the remaining nine were patients with DSM-III-R diagnosis of cocaine addiction (group III). MAO activity was assayed radiochemically with [14C]tyramine as a substrate (221 microM). The results of this study showed that platelet MAO activity [nmol of product formed x (mg protein)-1 x hr-1] (mean +/- SE) was significantly (p < 0.01) lower in all of these subjects (group I, 5.50 +/- 0.80; group II, 3.90 +/- 0.50; group III, 4.3 +/- 1.60) as compared with controls (14.85 +/- 1.13). Measurements of platelet MAO activity may provide us with a reliable biochemical marker for alcoholism and perhaps addiction to other substances of abuse (i.e., cocaine).

Ethanol, monoamines, and affect

Evidence suggests that ethanol self-administration is directly related to central norepinephrine (NE) activity and inversely related to central serotonin (5-HT) activity. Normal male volunteers participated in a placebo controlled crossover design to assess the effects of 1-tyrosine (TY) and 1-tryptophan (TP) (precursors of catecholamines and 5-HT, respectively) in combination with ethanol, on several neurobehavioral measures. Ethanol by itself produced negative effects on several dimensions of mood. Dysphoria was potentiated by TP in combination with ethanol and either unchanged or attenuated by the combination of TY and ethanol. Ethanol impaired verbal recall, and neither TP nor TY in combination with ethanol altered that impairment. The results are consistent with the hypothesis that 5-HT mediates some of the negative mood effects produced by ethanol or antagonizes some of its positive effects, while NE at least partly mediates ethanol's positive effects on mood. Ethanol's impairment of verbal memory appears to be mediated by mechanisms outside the monoamine systems.

Platelet MAO activity in type I and type II alcoholism

Lowered activity of the enzyme MAOB in the platelets and other tissues of alcoholics than of nonalcoholics is the most replicated biological finding in genetic research in alcoholism. Data presented here and elsewhere also indicate that the relationship between MAOB activity and alcoholism extends to the clinical subtypes referred to as Type I and Type II alcoholism. A detailed examination of the relationship between in vitro platelet MAOB activity levels, alcoholic subtype, and general mental health status among the relatives of the probands suggests that low MAOB activity is a marker of increased risk overall and that the families of Type II alcoholics have a higher genetic risk loading than do the families of Type I alcoholics. This increased genetic loading is probably due to the classification of Type II alcoholics on the basis of features related to severity of illness and additional psychiatric features such as personality disorders. Although the families of alcoholics tend to have higher levels of psychiatric illness compared to the general population, the overall risk is compounded in the families of Type II alcoholics, and these differences in underlying risk are reflected in the observed differences in MAOB activities. Thus, MAOB is not a biological/genetic marker of alcoholism sensu stricto but is rather a biological/genetic marker of an underlying pathophysiologic process leading to alcoholism and other psychiatric illness. The task now before us is to understand this process and how the activity of MAOB is involved.

The effects of ethanol on rat brain monoamine oxidase activities

In contrast to the reported behaviour of human platelet MAO-B, chronic ethanol feeding does not significantly affect the sensitivities of either MAO-A or -B from rat brain to inhibition by ethanol in vitro. The thermal stabilities of rat brain MAO-A and -B are not significantly affected by chronic ethanol feeding.

Association of monoamine oxidase (MAO) activity with alcoholism and alcoholic subtypes

A familial/genetic study of platelet monoamine oxidase (MAO) activity in alcoholics was carried out. MAO activities were determined using phenylethylamine (PEA) as substrate at Km concentration (1.2 microM) and at saturating concentration (12.0 microM). Complex segregation analysis of familial data indicated a single major gene mode of transmission of activity at both substrate concentrations. In addition, the present sample size (13 families, 108 members) proved sufficient to allow correlation analysis of enzyme activity with affection status and clinical subtypes of affecteds. MAO activity was significantly correlated with alcoholism at both Km and saturating substrate concentrations and a significant correlation between low MAO activity and Cloninger Type II alcoholism was seen at Km substrate concentration. These results confirm a hierarchical cosegregation of platelet MAO activity and alcoholism suggesting that MAO activity warrants continued status as a marker in alcoholism.

Mixture analysis of pursuit eye-tracking dysfunction in schizophrenia

Results of two recent studies suggest that a distinct subgroup of schizophrenic patients and their relatives have particularly deviant eye tracking. Such heterogeneity could be of considerable importance, as it may indicate significant pathophysiologic or etiologic heterogeneity in schizophrenia. An analysis of 101 consecutive-admission schizophrenic patients confirmed the existence of two distinct subgroups of patients with higher and lower levels of spatial [root mean square (RMS)] eye-tracking error. However, there was no heterogeneity in the disturbance of pursuit eye movements. Anticipatory saccades, which by definition add very large amounts of spatial tracking error, were more frequent in the "high" RMS error group. Rates of anticipatory saccades were similar in the "low" RMS error patient group and normal controls, and there was no heterogeneity in the expression of anticipatory saccades. Apparent heterogeneity in global indices of eye-tracking impairment in schizophrenia appears to be a measurement artifact reflecting the powerful influence of anticipatory saccades on global performance indices, rather than true heterogeneity in the expression of any specific eye movement abnormality.

A genetic familial study of monoamine oxidase B activity and concentration in alcoholics

Platelet monoamine oxidase B (MAO B) activity and concentration were studied in a small sample of alcoholic families (n = 8) and in 20 unrelated, nonalcoholic controls. Complex segregation analyses of familial data indicated that both activity and concentration are controlled by a single major gene locus with a multifactorial background effect accounting for 0-50% of the variance. When the alcoholic family members (n = 24) were compared with the controls, all determinations of activity display significant differences, whereas MAO B concentration levels showed no difference. These results indicated that the lowered MAO B activities frequently reported among alcoholics do not reflect a change in the number of MAO B macromolecules expressed in platelets, but could be caused by the presence of an inhibitor or by a polymorphic or variant form of the enzyme.

Why there is no gene for alcoholism

The search for and recognition of biological and genetic markers of alcoholism are discussed in the context of a heuristic model of human alcoholism as a complex, multilocus, heterogeneous disorder. Implications of this model for the interpretation of results from both linkage and association studies are presented.

Low platelet gamma-aminobutyrate aminotransferase and monoamine oxidase activities in chronic alcoholic patients

The activities of gamma-aminobutyrate aminotransferase (GABA-T) and monoamine oxidase (MAO) were estimated in blood platelets from 25 male chronic alcoholics and from 27 healthy male volunteers without histories of alcohol abuse. Based on clinical criteria, the alcoholics were classified into type 1 or type 2 alcoholism. The activity of GABA-T was found to be lower both in type 1 and type 2 alcoholics than in healthy volunteers. With regard to MAO, the platelet activity was found to be significantly lower only in type 2 alcoholics in concordance with previous reports. No significant correlation was found between the activities of GABA-T and MAO in the blood platelets of healthy volunteers. The inhibitory effect of 400 mM ethanol on the platelet MAO activity increased with decreasing concentrations of the substrate phenylethylamine. The degree of inhibition of ethanol on the platelet MAO activity, however, did not differ significantly between alcoholics and controls.

Utility and evaluation of biochemical markers of alcohol consumption

Biochemical markers of alcohol consumption have a variety of clinical and research applications. Currently available markers such as the serum gamma-glutamyl transpeptidase (GGT), serum transaminases, and the mean corpuscular volume (MCV) lack sufficient sensitivity and specificity to be used for screening of alcoholism in ambulatory patients. However, these tests can be helpful in corroborating a clinical suspicion of alcoholism. A number of special laboratory markers of alcoholism recently have been developed which may have increased diagnostic accuracy. Promising potential markers include serum carbohydrate-deficient transferrin (CDT), red blood cell acetaldehyde, and acetaldehyde adducts. The application of reliable and practical markers of alcohol consumption could lead to significant improvements in the treatment of alcoholism and in the assessment of clinical trials.

Personality traits and platelet monoamine oxidase activity in alcoholic women

Twenty-nine women, sent to an inpatient treatment facility for rehabilitation and social training after treatment for heavy alcohol abuse, were compared with 29 female students of pharmacy or medicine with regard to platelet monoamine oxidase (MAO) activity and extraversion-impulsivity and anxiety-proneness personality traits. The alcoholic females were found to have slightly lower platelet MAO activity than the controls, the difference being considerably smaller than that previously found between male alcoholics and male controls. The personality pattern of the female alcoholics is in line with that previously found in alcoholic males. Thus, the female alcoholics were characterized by high anxiety proneness, impulsive acting-out behaviour, sensation seeking, social withdrawal, and a hostile attitude.

Medicalizing the drug war

Recent findings in the field of psychopharmacology pertain to the abuse of drugs and alcohol among criminal offenders and have implications for new management techniques. Drugs of abuse exert their effects on areas of the brain responsible for pleasure, providing a powerful reinforcement for drug usage. Furthermore, there is a prevalence of psychological, psychiatric and social dysfunctions that antedate drug use which are identifiable at an early age. It is suggested that drugs of abuse differentially influence users via these biological, psychological and social mechanisms, reinforcing the development of serious and chronic abuse in a vulnerable subgroup. Studies of drug abuse specially indicate that within this subgroup, antisocial behavior precedes and exacerbates drug abuse, and multiple risk factors contribute to the concomitant development of criminality and drug abuse. Early detection and comprehensive treatment of underlying disorders that may both precipitate and result from drug abuse promise to improve possibilities for prevention and reducing relapse rates. Furthermore, the inclusion of pharmacologic treatments may further enhance the success of conventional drug treatments. This article proposes that incorporating scientific data and medicalizing our approach to drug abuse is essential to win the war against drugs.

Platelet MAO in subtypes of alcoholism

A number of investigators have observed low platelet monoamine oxidase (MAO) activity in alcoholism. There is also preliminary evidence suggesting that low enzyme activity is principally associated with one of two putative subtypes of alcohol dependence, i.e., type II (male limited). The results of this study are consistent with two previous reports of reduced platelet MAO activity in type II male alcoholics as compared with type I male alcoholics and normal, healthy male controls. Type I (milieu-limited) alcoholics showed a smaller reduction in enzyme activity. The observed differences do not appear to be related to concurrent use of other psychoactive substances, characteristic differences in age between type I alcoholics and type II alcoholics, antisocial personality disorder, or variation in platelet size. Low platelet MAO activity in alcoholics is possibly related to both state and trait factors and may be a useful biochemical measure to assist with subtyping.

Clinical characteristics of female alcoholics with low platelet monoamine oxidase activity

The aim of the present study was to see if female alcoholics had low platelet MAO activity and whether there was a correlation between low MAO activity in female alcoholics and specific clinical characteristics often observed in type II male alcoholics. In earlier studies, male alcoholics have been subdivided into type I and type II alcoholics. Type II alcoholics were characterized by early onset, a high frequency of depression and alcoholism in first degree relatives, a high frequency of drug abuse and social complications, sensation seeking behavior, extraversion, impulsive sensation seeking psychopathy, and low platelet MAO activity. In the present series it was demonstrated that the female alcoholics had significantly lower platelet MAO activities than the female healthy volunteers. The subgroup of female alcoholics with low platelet MAO activity, however, did not differ from female alcoholics with normal platelet MAO activity in the same way as male alcoholics with low platelet MAO activity have been shown to differ from male alcoholics with normal platelet activity. They did not have early onset, higher frequency of depression or alcoholism in their first degree relatives, nor more social complications than the female alcoholics with normal platelet MAO activity. Furthermore, they did not differ from the female alcoholics with normal platelet MAO activity in any personality trait covered by the Karolinska Scales of Personality (KSP).

Low platelet monoamine oxidase activity in borderline personality disorder

Platelet monoamine oxidase (MAO) activity was significantly lower in nonpsychotic, nonorganic, unmedicated male inpatients with DSM-III-R borderline personality disorder (BPD) than in nonpsychiatric controls. Patients with BPD who also met DSM-III-R criteria for antisocial personality disorder had significantly lower MAO activity than those with BPD alone. Low MAO activity in this sample did not appear to be related to the comorbid presence of major depressive disorder or a history of substance abuse.

EEG sleep, lithium transport, dexamethasone suppression, and monoamine oxidase activity in borderline personality disorder

Twenty-one patients who met DSM-III criteria for borderline personality disorder (BPD) and also scored at least 7 on the Diagnostic Interview for Borderlines (DIB) were assessed on four biological markers: electroencephalographic (EEG) sleep, in vitro lithium ratio, platelet monoamine oxidase (MAO), and dexamethasone suppression test (DST). REM latency averaged 58.66 (SD 14.39); platelet MAO averaged 21.74 (SD 10.33); and lithium ratio was 0.357 (SD 0.139) in the BPD patients. All of those values were significantly abnormal. Many patients had abnormalities on three or four measures. These patients in general had multiple Axis I diagnoses from the Diagnostic Interview Schedule (DIS), and these Axis I diagnoses tended to produce patient clusters. Patients with a DIS diagnosis of schizophrenia, mania, hypomania, or schizoaffective mania had elevated lithium, low MAO, and normal EEG sleep, while those patients with coexisting major depression tended to have short rapid eye movement (REM) latency, high REM density, and normal MAO and lithium ratio. Only two patients were nonsuppressors on the DST, confirming recent reports of normal DST results in personality disorders.