Toward a biochemical classification of depressive disorders, VI: Platelet MAO activity and clinical symptoms in depressed patients

Association study of a functional MAOA-uVNTR gene polymorphism and personality traits in Chinese young females

Monoamine oxidase A (MAOA), a mitochondrial outer membrane enzyme, degrades biogenic amines including norepinephrine, dopamine and serotonin, which have been implicated in the expression of personality traits. We tested the associations between functional MAOA-uVNTR genetic variants and personality traits in a cohort of 370 healthy young Chinese females. Subjects who were homozygous for the 4-repeat allele of the MAOA-uVNTR gene tended to have a higher total score on the Harm Avoidance (HA) dimension of the Tridimensional Personality Questionnaire (TPQ) (p = 0.056), and had a significantly higher score on subdimension 4 of HA (p = 0.020) compared with the 3-repeat carriers. No significant association was demonstrated for MAOA-uVNTR polymorphism and the other two dimensions (Novelty Seeking and Reward Dependence) of TPQ. These results suggest that genetic variants of the MAOA gene may play a role in HA, but not in Novelty Seeking or Reward Dependence.

Relationship between depression and borderline personality disorder

The frequent occurrence of depressive symptoms in patients with borderline personality disorder has generated considerable interest in the nature of the relationship between borderline personality disorder and the depressive disorders. Data from the perspectives of phenomenology, biology, family history, course of illness, comorbidity patterns, and treatment response have been brought to bear on the question. Reviews based on research available by 1985 and 1991, respectively, arrived at differing conclusions: (1) that both disorders shared common but non-specific sources, and (2) that the two disorders were unrelated but co-occurred because of the high prevalence of each. Since the time of these reviews, additional evidence has become available from a wider range of biological investigations, better controlled comorbidity studies, studies of the relationship of psychosocial stressors to the course of each disorder and neuroimaging studies. In reviewing the more recent findings, we propose the less parsimonious hypothesis that the disorders co-occur, both because they share some common biological features and because the psychosocial sequella of each can contribute to the development of the other.

Individual differences in changes in mood and platelet monoamine oxidase (MAO) activity during hormonal replacement therapy in menopausal women

Estrogen replacement treatment in menopausal women has been reported to have a positive effect on mood states. However, the addition of a progestin partially negates this positive effect in some women. The opposite effects of estrogen and progestin on mood may relate to their opposite effects on adrenergic and serotonergic neural function. In a double-blind, placebo-controlled, crossover study, 38 nondepressed menopausal women were cyclically treated with estrogen and estrogen plus progestin, or with placebo, for five 28-day cycles. This paper identifies the pretreatment attributes of women who do and do not have negative mood responses to progestin, and examines the relationship of these adverse side-effects to platelet monoamine oxidase (MAO), a marker of adrenergic and serotonergic functioning. Adverse mood responses to progestin occur in women with a long duration of menopause, low pretreatment serum estradiol and testosterone levels, high pretreatment serum FSH levels, low pretreatment platelet MAO activity, and pretreatment mood abnormalities. We conclude that adverse mood response to the addition of a progestin occurs in menopausal women who have low pretreatment gonadal hormone levels secondary to a long duration of menopause. Impaired central nervous system adrenergic and serotonergic functioning also may be a factor predisposing to a negative mood response to progestin.

Clinical symptoms and platelet monoamine oxidase in subgroups and different states of affective disorders

Platelet monoamine oxidase activity (MAO) and clinical symptoms were examined in 116 individuals, 32 acute depressed patients and 84 healthy controls. The enzyme activity was lower in depressed women than controls. MAO activity correlated positively with rated clinical state in depressed women but not in depressed men. Patients were reexamined after 10 years and categorized into affective psychosis (endogenous) or neurotic depression (International Statistical Classification of Diseases, Injuries and Causes of Death, 1987; ICD-9). Neurotic depressed occurred frequently in the low activity group. Endogenously depressed showed positive correlation between MAO activity and rated clinical state. The association between platelet MAO activity and clinical state is discussed.

Detoxified alcoholics, major depressives and tyramine sulphate excretion

The excretion of tyramine sulphate after challenge with an oral load of tyramine was assessed in recently detoxified, clinically depressed alcoholics and a matched group of major depressives. Tyramine excretion in the alcohol group (mean 5.95 ± 3.28 mg/3 h SD) was in the range previously observed in controls and was significantly higher than in the matched depressives (mean 3.43 ± 2.37 mg/3 h SD). Tyramine sulphate excretion has been suggested as a genetic vulnerability marker for major depression. This study suggests that depression associated with alcohol withdrawal is not characterised by decreased tyramine sulphate excretion after oral tyramine challenge, such decreased conjugation only being present, perhaps, in those patients with pre- existing endogenous depressive vulnerability. Although a genetic link between alcoholism and depression exists, these results support the absence of such a link to major depression.

Relationship between platelet monoamine oxidase B activity and alleles at the MAOB locus

Genetic variations in monoamine oxidase (MAO)-B activity have been proposed to have a contributory role in several neurologic and psychiatric diseases. Variations in activity could affect rates of degradation of exogenous amines, including toxins, precursors of toxins (like 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), or false transmitters, and of endogenous amines, such as neurotransmitters. In this study a highly polymorphic (GT)n repeat element was used to mark alleles at the MAOB locus. The MAOB allele status and levels of platelet MAO-B activity were determined for 41 control males. No correlation was noted between specific alleles and levels of MAO-B activity in this sample set. This suggests that the structural gene for MAOB is not usually the primary determinant of activity levels in platelets.

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.

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.

Platelet monoamine oxidase activity and 5-hydroxytryptamine uptake in agoraphobic patients

Platelet MAO activity and platelet serotonin uptake were determined in 20 agoraphobic and 16 neurotic depressive out-patients, and 19 healthy volunteers. Agoraphobic patients were characterised by significantly higher mean values of platelet MAO activity compared with the other two groups, while neurotic depressive patients exhibited significantly higher maximum platelet serotonin uptake velocity. These findings are compatible with an abnormality in the uptake and metabolism of serotonin.

Psychiatric morbidity, platelet monoamine oxidase and tribulin output in headache

A significantly higher proportion of patients with headache showed scores in the psychopathological range of the General Health Questionnaire (GHQ) compared with controls, with ratings particularly high on the anxiety and depression subscales. Across the whole group, there was a significant negative correlation between platelet monoamine oxidase (MAO) activity and GHQ score overall, and with the anxiety and depression subscales. There was a significant positive correlation between platelet MAO activity and urinary output of the endogenous MAO inhibitor, tribulin. Within the migraine group, there was a significant negative correlation between tribulin output and GHQ score. These findings suggest that the biochemical nature of the anxiety associated with migraine may differ from that in other conditions such as generalized anxiety disorder where high platelet MAO activity and high tribulin output have been reported.

Characterization of monoamine oxidase activity present in human granulocytes and lymphocytes

The characterization of monoamine oxidase (MAO) activity in lymphocytes and granulocytes was studied by using cells prepared from human blood. The specific activities of the enzyme towards beta-phenylethylamine (PEA), benzylamine (Bz), tyramine (TYR) and 5-hydroxytryptamine (5-HT) were found to be 5-times higher in lymphocytes than in granulocytes. The absence of the semicarbazide-sensitive amine oxidase (SSAO) was confirmed by the lack of effect of semicarbazide on the benzylamine oxidation. The presence of MAO-B was corroborated by the inhibition of PEA oxidation with nanomolar deprenyl concentrations and by inhibition of TYR oxidation with high clorgyline concentrations, as well as by the simple sigmoid curve obtained in both cases. These results, together with the substrate preferences, suggest that the MAO activity of human granulocytes and lymphocytes is predominantly of the B form. For each fraction the kinetic constants were determined towards PEA, TYR and Bz as substrates. The Km values were similar for both cellular samples, whereas the Vmax values were higher in lymphocytes than in granulocytes. MAO-B was titrated with [3H]pargyline in order to find out the number of active sites. The corresponding molecular concentration, Kcat values and turnover number showed the presence of related enzymes in human granulocytes and lymphocytes.

Evidence for possible linkage between genetic markers and affective disorders

Studies of the underlying components of affective disorders are particularly difficult because of the confounding effects of both genetic and environmental factors. Linkage analysis is a useful tool in delineating the etiology of affective disorders, as it is unlikely that linkage between behavioral traits and blood group polymorphisms could result from environmental effects. The present study used the robust Haseman and Elston sibpair method to analyze linkage between 24 genetic markers and affective disorder in 34 nuclear families from 25 pedigrees (195 people). The probands were ascertained as part of the ongoing NIMH Collaborative Depression Study. Indications of linkage between familial pure depressive disease and MNS and depression spectrum disease and ORM were found, as had been previously suggested. There was also suggestive evidence for linkage between the latter and GC. Results are discussed in terms of methodological differences with previous studies.

Biology of depression

Research over the past three decades has led to a greater understanding of the biologic basis of depression. Observations that certain medications could improve or worsen mood led to the development of hypotheses describing the possible role of specific neurotransmitters in the brain in depression. Modifications of these original hypotheses focused on altered receptor function, failures in the regulation of neurotransmitter systems, and interactions of the monoamines with cholinergic systems. Strategies using endocrinologic measurements in the evaluation of the depressed patient have provided researchers with new clues regarding disordered neuroendocrine function in depression and clinicians with new tests to aid in diagnosis and management. Moreover, the development of standardized sleep EEG methodology has proven useful for the identification of characteristic sleep abnormalities in depression. Although there are many methodologic and clinical problems still to be resolved, the use of biological markers in the assessment of the depressed patient is increasing, and is likely to be of significant importance in the future. Finally, recent advances in molecular genetics hold promise for further advances in our understanding of the inheritance and biochemistry of depression.

Platelet MAO activity and the cortisol response to dexamethasone in major depression

Previous studies have sometimes found a positive relationship between platelet monoamine oxidase (MAO) activity and dexamethasone nonsuppression in depressed patients. To assess this relationship in more detail, we examined the association between these two biological variables in unmedicated depressed patients. A positive correlation between platelet MAO activity and 8:00 AM serum cortisol levels following an overnight dexamethasone test (1 mg) was observed. The relationship between high and low platelet MAO activity (median split) and suppression of serum cortisol levels was also significant. These relationships were stronger in bipolar patients. Multiple regression revealed that postdexamethasone 8:00 AM dexamethasone levels and platelet MAO activity were independent predictors of the 8:00 AM cortisol levels following dexamethasone. The possibility that platelet MAO activity may be a peripheral marker of brain serotonergic activity which in turn may affect various aspects of the hypothalamo-pituitary-adrenal axis activity, is discussed. We also found that all nine depressed patients studied greater than or equal to 15 days after admission were suppressors. Platelet MAO activity, but not 8:00 AM pre- or postdexamethasone serum cortisol, was related to the severity of depression.

Biological mechanisms in posttraumatic stress disorder. Relevance for substance abuse

Recent studies suggest a significant biological contribution to posttraumatic stress disorder (PTSD). In particular, central catecholamine and endogenous opioid systems have been implicated both in this syndrome and in substance abuse. We review relevant animal and human studies that support these hypotheses and suggest that this overlap may contribute to the incidence of substance abuse in PTSD. The animal studies have primarily employed the learned helpless and conditioned emotional response models and have included assessments of brain catecholamines, locus ceruleus activity, and behavioral correlates in rodents and nonhuman primates. Human studies have used only indirect measures to assess these variables. However, both therapeutic approaches and attempts at self-medication for PTSD have supported this hypothesis.

Psychiatric morbidity and platelet monoamine oxidase activity in cancer patients

Psychometric ratings for both anxiety and depression in 30 cancer patients were significantly elevated compared with values in 16 controls. The scores were especially high in the 14 patients who did not have breast cancer. This group also had significantly greater platelet monoamine oxidase activity than either the breast cancer patients or controls. Platelet monoamine oxidase activity values correlated significantly with both depression and anxiety scores in the whole cancer group.

Psychotic and nonpsychotic depressions: II. Platelet MAO activity, plasma catecholamines, cortisol, and specific symptoms

Preliminary data are presented on levels of plasma cortisol, dopamine (DA), epinephrine (EPI), and norepinephrine (NE) before and after dexamethasone in 22 depressed patients (of whom 4 were psychotic). Platelet monoamine oxidase (MAO) activity, determined in 19 of the depressed patients, was significantly higher in the 4 psychotic patients than it was in the 15 nonpsychotic patients. Positive correlations were observed before and after dexamethasone among cortisol, DA, EPI, and platelet MAO. After dexamethasone, plasma NE correlated negatively with DA, EPI, and cortisol. The various correlations were due largely to the inclusion of the psychotic depressive subgroup. Data are also presented on the relationships between these biological measures and specific signs and symptoms.

Platelet MAO activity and psychosis proneness in college students

A population of individuals potentially at risk for psychiatric disorders was identified by screening 633 college students using the Wisconsin Scales for psychosis proneness. Platelet monoamine oxidase (MAO) activity was measured in high-scoring individuals and controls using 14C-benzylamine. Males with deviant scores on the Perceptual Aberration-Magical Ideation Scale showed a bimodal distribution of platelet MAO activity. Kinetic analysis of platelets from probands with the highest and lowest levels of MAO activity in this group revealed differences in Vmax but not in Km. Since abnormal platelet MAO activity has been linked to psychiatric vulnerability, the results provide further support for the validity of the Wisconsin Scales as predictors of psychopathology.

Toward a biochemical classification of depressive disorders IX. DST results and platelet MAO activity

Post-dexamethasone cortisol and platelet monoamine oxidase (MAO) activity levels were examined in 50 depressed patients. The incidence of non-suppression was significantly greater in patients with high platelet MAO activity than in those with low activity. Similar results were obtained when males and females were analysed separately. The mean 4 p.m. post-dexamethasone cortisol level was significantly higher in those patients who had high MAO activity than in their low MAO counterparts. Moreover, a statistically significant positive correlation was observed between platelet MAO activity and 4 p.m. post-dexamethasone cortisol levels.

Toward a biochemical classification of depressive disorders--VIII. Platelet monoamine oxidase activity in subtypes of depressions

Platelet monoamine oxidase (MAO) activity was examined in 77 depressed patients (40 males and 37 females) and 28 controls (14 males and 14 females). Patients were compared across increasingly specific diagnostic groupings in a four-step data analytic procedure. In step 1, MAO activity in the total sample of depressed patients was compared with that of control subjects. In step 2, Unipolar depressed patients were compared with Bipolar (Bipolar I and Bipolar II) depressed patients. In step 3, Unipolar depressed patients with and without schizotypal features were compared. In step 4, both the nonschizotypal Unipolar patients and compared. In step 4, both the nonschizotypal Unipolar patients and nonschizotypal Bipolar patients were separated into those who met RDC criteria for a definite Endogenous depression and those who did not; and platelet MAO activity was compared in the resulting four groups. Results indicated significantly higher platelet MAO activity in nonschizotypal Unipolar Endogenous depressed patients than in nonschizotypal Bipolar Endogenous depressed patients or nonschizotypal Unipolar Other patients. In addition, the presence of a definite Endogenous depressive syndrome was associated with greater overall symptom severity in both Unipolar and Bipolar depressed patients. Findings are discussed with respect to the conflicting results reported in previous studies of MAO activity in patients with depressive disorders.

Platelet monoamine oxidase and phenolsulphotransferase M and P in cancer

Phenolsulphotransferase and monoamine oxidase inactivate a wide range of dietary and endogenous phenols/monoamines by sulphoconjugation and oxidative deamination respectively. In this study, both enzymes were measured in platelets from cancer patients and controls. Of the two variants of phenolsulphotransferase, activity of the P form was normal in all groups. Activity of the M form was, however, significantly less than control values in patients with cancer of the rectum and bowel but not in other cancer patient groups. If this finding reflects enzyme activity elsewhere in the body and is not merely a manifestation of an abnormal platelet population, the deficit could expose affected subjects to the action of potentially carcinogenic dietary phenols. Platelet monoamine oxidase activity was significantly raised in the cancer group as a whole, and in all sub-types investigated apart from breast cancer. The increase in the cancer group as a whole was independent of sex, age, drugs, radiotherapy, smoking or platelet count. Its mechanism and significance are unknown but there may be links with the patients' psychiatric state.

Platelet monoamine oxidase activity in the psychoses: relationship to symptoms and lithium response

The kinetics of platelet monoamine oxidase (MAO) were studied in 100 psychotic and manic patients and 36 controls. No relationship was found between MAO activity and response to lithium in the schizophrenic-like illnesses. However, the data do suggest there is an association between enzyme affinity (Km) and specific symptom clusters. Patients with the low Km variant of platelet MAO are enriched in depressive symptoms, while those with the high Km variant are enriched in manic symptoms.

Dopamine and depression: a review of recent evidence. I. Empirical studies

This paper reviews evidence from human, predominantly clinical, studies, relevant to the hypothesis that depression involves reduced levels of dopamine (DA) function. With the exception of Parkinson's disease, there is little evidence that treatments which decrease DA function are potent inducers of depression, but it is argued that such a relationship might not necessarily be expected. There is good evidence that the nigro-striatal DA system is underactive in retarded depressions, and some evidence that DA agonists are therapeutically effective in these cases. It remains unclear whether changes in DA function are primary or secondary.

Endogenous inhibitors of monoamine oxidase present in human cerebrospinal fluid

Inhibitory activity against the enzyme monoamine oxidase is present in low molecular weight fractions (less than 100,000) of human cerebrospinal fluid. These endogenous substances of different molecular weights (3000 to more than 35,000) act like monoamine oxidase inhibitor drugs to inhibit both type A and type B monoamine oxidase.

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

Platelet monoamine oxidase activity and plasma trace acid levels in 29 patients classified as agoraphobics was estimated. MAO activity towards p-tyramine and beta-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.