Platelet MAO activity and the dexamethasone suppression test in depressed patients

ROC analysis of dexamethasone suppression test threshold in suicide prediction after attempted suicide

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis function is associated with suicidal behavior. In suicide attempters with mood disorder, the non-suppressor status in the dexamethasone suppression test (DST) is associated with suicide indicating that HPA-axis hyperactivity is a biological risk factor for suicide and may be a useful predictor. The threshold of 5 microg/dl for cortisol levels measured at 08:00 a.m. or 4:00 p.m. following dexamethasone at 11:00 p.m. to define the DTS nonsuppression was derived as being optimal for the separation of melancholia and nonmelancholic conditions rather than the prediction of suicide. A different threshold may offer a better identification of suicide. The aim of this study was to find the optimal threshold level of post DST plasma cortisol at 4 p.m. for suicide prediction using receiver operating characteristics (ROC) analysis. A cohort of 106 depressed inpatients with an index suicide attempt admitted to the department of Psychiatry at the Karolinska University Hospital between 1980 and 2000, were submitted to DST and followed up for causes of death. During the follow-up (mean 17 years), 25 suicides (24%) were identified. The ROC analysis revealed that a lower threshold of 3.3 microg/dl for the nonsuppressor status predicted 17 of 25 suicides (sensitivity of 68%) compared with 15 of 25 suicides (sensitivity 60%) with a conventional threshold of 5 microg/dl at 4:00 p.m. In male suicide attempters the lower threshold for pathological DST result (3.3 microg/dl) changed the Odds ratio from 6.7 till 18. In female suicide attempters a higher threshold (7.3 microg/dl) optimised the value of DST as a biological test for suicide prediction indicating a gender difference.

Combined biological tests for suicide prediction

Disturbances in serotonin neuroregulation and in hypothalamic-pituitary-adrenal axis activity are both likely, and possibly independent, factors in the genesis of suicidal behavior. This analysis considers whether clinically accessible measures of these two disturbances have additive value in the estimation of risk for suicide. Seventy-four inpatients with RDC major or schizoaffective depressive disorders entered a prospective follow-up study from 1978-1981, underwent a dexamethasone suppression test (DST) and had fasting serum cholesterol levels available in the medical record. As reported earlier, patients who had had an abnormal DST result were significantly more likely to commit suicide during follow-up. Serum cholesterol concentrations did not differ by DST result and low cholesterol values were associated with subsequent suicide when age was included as a covariate. These results indicate that, with the use of age-appropriate thresholds, serum cholesterol concentrations may be combined with DST results to provide a clinically useful estimate of suicide risk.

Monoamine oxidase and cortisol response in depression and schizophrenia

The relationship between hypothalamic-pituitary-adrenal (HPA) axis function and platelet monoamine oxidase (MAO) activity was examined in drug-free depressed (n = 32) and schizophrenic (n = 36) inpatients. HPA function was measured by determining plasma cortisol levels at 8:30 a.m. and 11 p.m. before, and 8:30 a.m., 4 p.m., and 11 p.m. after administration of 1 mg of dexamethasone (DEX). There was a significant correlation between platelet MAO activity and all post-DEX cortisol levels (8:30 a.m., 4 a.m., and 11 p.m.) in depressed patients, and MAO activity and pre-DEX cortisol levels (11 p.m.) in schizophrenic patients. MAO activity was significantly higher in depressed DST nonsuppressors than in suppressors, and there were more DST nonsuppressors in high-MAO groups as compared with low-MAO groups. Our results thus suggest a strong relationship between platelet MAO activity and HPA function in depressed patients. These biochemical markers are potentially useful in the identification of biochemically and clinically homogeneous subgroups of depressed patients.

Why not treat melancholia with melatonin and tryptophan and treat seasonal affective disorders with bright light?

Symptoms, signs, and biologic markers in melancholia are suggested to be secondary to a deficiency of melatonin, with the resultant increase of monoamine oxidase activity, increase in plasma cortisol, and alteration of sleep physiology. Tryptophan and melatonin, given shortly before bedtime, seem to be rational treatment for melancholia. Bright light may be effective in seasonal affective disorder because it markedly strengthens the zeitgeber that controls biologic rhythms in human beings.

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.

Rapid antidepressant response to alprazolam in depressed patients with high catecholamine output and heterologous desensitization of platelet adenylate cyclase

The present study examined the relationship between 24-hr urinary catecholamine (norepinephrine and epinephrine) output and measures of platelet adenylate cyclase (AC) activity in depressed patients (n = 17) and control subjects (n = 10). In both groups, significant inverse correlations were observed when 24-hr urinary catecholamine levels were examined in relation to measures of both receptor-mediated (prostaglandin D2 and alpha 2-adrenergic) and postreceptor-mediated (NaF) platelet AC enzyme activities, suggesting that circulating catecholamines may regulate platelet AC by heterologous (agonist-nonspecific) desensitization of the AC enzyme complex. Depressed patients who had favorable antidepressant responses to alprazolam had significantly higher pretreatment urinary catecholamine output and lower receptor-mediated platelet AC enzyme activities than control subjects, whereas the nonresponders did not. After 8 days of treatment with alprazolam, urinary catecholamine levels declined significantly. In responders, receptor-mediated measures of platelet AC activity increased significantly by day 8 to values comparable to those in control subjects; but similar changes were not observed in nonresponders. Prior to treatment, responders showed a strict linear relationship between receptor-mediated (prostaglandin D2) and postreceptor-mediated (NaF) stimulation of platelet AC activity through the stimulatory guanine nucleotide regulatory protein (Ns), whereas nonresponders did not. This suggests the presence of two distinct coupling interactions between platelet prostaglandin D2 receptors and the stimulatory guanine nucleotide regulatory protein in responders and nonresponders to the antidepressant effects of alprazolam prior to treatment. The authors propose that catecholamines, possibly acting through prostaglandins, may regulate platelet AC enzyme activity by heterologous desensitization occurring through postreceptor mechanisms.

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.

Relationship of platelet MAO activity to characteristics of major depressive illness

Sixty-seven patients (greater than or equal to 55 years of age) with major depressive disorder had pretreatment assays of platelet monoamine oxidase (MAO) activity. As in previous studies, women had higher MAO activity than men, and MAO activity was positively correlated with age. Patients with melancholia (DSM-III) had significantly higher MAO activity than those without melancholia. This finding may reflect the higher MAO activity associated with the symptoms of anhedonia and mood autonomy. Anxiety also was correlated with higher MAO activity, as was a positive family history of depression. In addition, postdexamethasone cortisol levels were correlated with platelet MAO activity.

Is there a metabolic basis for the fibrositis syndrome?

Patients with the fibrositis syndrome experience moderately severe musculoskeletal discomfort, mood changes associated with nonrestorative sleep, and tenderness to palpation at specific body sites. There is no characteristic abnormal laboratory finding in these patients to help identify the population. A report by Moldofsky and Warsh (Pain 1978; 5: 65-71) of low serum levels of free tryptophan in patients with severe fibrositis syndrome is intriguing but remains unexplained. Those data plus the observation by Hudson et al (Am J Psychiatry 1985; 142: 441-446; Biol Psychiatry 1984; 19: 1489-1493) that patients with fibrositis syndrome exhibit an increased prevalence of anxiety and depression suggest a number of possible avenues for further study. They include potential alterations in the homeostasis of catecholamines, corticosteroids, serotonin, aromatic amino acids, platelet membrane receptor levels, and the activity of platelet membrane monoamine oxidase. Among these possibilities, evidence is now available that suggests an increased production of catecholamines in fibrositis syndrome.

Platelet MAO activity and the dexamethasone suppression test in bipolar depression

The correlation between postdexamethasone cortisol levels after the dexamethasone suppression test (DST) and platelet monoamine oxidase (MAO) activity was studied in 31 depressed female inpatients with Research Diagnostic Criteria primary, endogenous, bipolar depression (12 bipolar 1 and 19 bipolar 11). Out of the 31 patients, 25 showed abnormal DST results. Platelet MAO activity did not differ significantly from the matched control group. There was a trend that patients with higher MAO activity had lower postdexamethasone cortisol levels, but it was significant only for the 0800 hr cortisol levels.

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.

Neuroendocrine changes in depression

Biological research in depression has concentrated on 'endogenous' depressions and over the past 30 years has been guided by the amine theory. Neuroendocrine abnormalities in depression have been reported for over 20 years and include changes in the hypothalamic-pituitary-adrenal and thyroid axes, in growth hormone and prolactin secretion. As neurotransmitters regulate neuroendocrine secretion, inter-relationships between neurochemical and neuroendocrine abnormalities may provide a window for understanding the pathophysiology of depression. The availability of these biological markers for depression opens new possibilities for research in psychiatric diagnosis and for management.

Enhanced signal transduction by adenylate cyclase in platelet membranes of patients showing antidepressant responses to alprazolam: preliminary data

The triazolobenzodiazepine, alprazolam, was administered to 11 depressed patients over a period of six weeks, and six patients showed a favorable antidepressant response. There were no significant differences between responders and nonresponders in age, pretreatment Hamilton Depression Rating Scores, 4 p.m. postdexamethasone plasma cortisol levels, or platelet monoamine oxidase activities. Blood levels of alprazolam were not meaningfully different in responders and nonresponders when measured on treatment day 8. However, on treatment day 8, significantly enhanced prostaglandin D2-stimulated platelet adenylate cyclase activity, greater suppression of prostaglandin D2-stimulated platelet adenylate cyclase activity by epinephrine, and enhanced sodium fluoride-stimulated platelet adenylate cyclase activity were seen in the six patients who went on to respond to alprazolam, but not in the five nonresponders. In contrast, there were no significant changes in prostaglandin D2, (-)-isoproterenol, or fluoride ion-stimulated leukocyte adenylate cyclase activity in responders or nonresponders. No meaningful changes were observed in the mean densities of either the high-affinity platelet alpha 2-adrenergic receptor (for 3H-p-aminoclonidine) or the leukocyte beta-adrenergic receptor (for 3H-dihydroalprenolol) in responders or nonresponders. The present findings, taken in conjunction with findings from other recent studies, suggest that enhanced coupling between certain neurotransmitter or hormone receptors and adenylate cyclase through the guanine nucleotide regulatory proteins may help explain the antidepressant effects of alprazolam and possibly other forms of antidepressant treatment.

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.

Biosocial theory of psychopathology: a three by three factor model

An effort has been made in this paper to describe a broad based theoretical scheme for understanding emotional disorders in mentally retarded individuals. Incorporating research from a broad group of professionals and researchers is stressed, and some efforts to point out where additional research can further clarify the postulates noted here were made. Although the emphasis has been on the mentally retarded, it is likely that the implications of this view of psychopathology have credence for other populations as well. It cannot be stressed enough that those who propose theoretical models should also be willing to conduct many experimental studies as a means of supporting or refuting claims, and as a means of further clarifying theories that have been proposed. Efforts of this sort have rarely been the case and may be due to the long term dedication and hard work required. The work of Ellis, and Zeamon and House, who have conducted research on memory and learning strategies, are two of the welcome but rare exceptions to this criticism in the general literature. Similarly, Zigler and Menolasceno's efforts provide fine examples of how theoretical models might be empirically validated. The hypotheses in this theory have been made in a loosely constructed descriptive fashion to take into account a broad array of research, and to allow for later modifications based on the findings that emerge from studies on the topic. It is stressed that a link must be drawn between etiology, assessment, and treatment, if a model with maximum practical benefit is to emerge. This situation can only happen when information and developments from various disciplines and empirically supported theoretical views are synthesized.

A corticosteroid/dopamine hypothesis for psychotic depression and related states

In recent years, considerable data have emerged that psychotic (delusional) depression is characterized by pronounced increases in hypothalamic-pituitary-adrenal (HPA) axis activity and positive responses to combined treatment with tricyclic antidepressants and antipsychotic (dopamine-blocking) agents. Recently, a number of observations in several species, including man, point to glucocorticoids' increasing dopamine activity in a variety of tissues and this effect is particularly marked in rat brain mesolimbic dopamine systems. We propose that glucocorticoids' enhancement of dopaminergic activity may explain the development of psychosis/delusions in the context of the depressive episode. Data in support of the hypothesis are presented and the identification of possible enzymatic risk factors are discussed. These interactions also have implications for understanding the biology of corticosteroid-induced psychoses in medical patients and some of the psychiatric complications of Cushing's Disease.