Platelet MAO-B activity in anxiety and depression

Reduced Platelet MAO-B Activity Is Associated with Psychotic, Positive, and Depressive Symptoms in PTSD

Post-traumatic stress disorder (PTSD) is a trauma-related disorder. Platelet monoamine oxidase (MAO-B) is a peripheral biomarker associated with various symptoms in different psychopathologies, but its role in PTSD or different symptoms in PTSD is not clear. This study elucidated the association between platelet MAO-B activity and clinical symptoms occurring in PTSD. Platelet MAO-B activity was determined in 1053 male Caucasian subjects: 559 war veterans with PTSD (DSM-5 criteria), 62 combat exposed veterans who did not develop PTSD, and 432 non-combat exposed healthy controls. Clinical symptoms in PTSD were determined using CAPS and PANSS. Platelet MAO-B activity, controlled for the effect of smoking, was significantly increased in PTSD with severe versus mild and moderate traumatic symptoms, and was significantly decreased in PTSD subjects with severe versus mild positive, psychotic, and depressive symptoms. This finding was further confirmed with reduced platelet MAO-B activity in PTSD veterans with severe versus mild individual items of the PANSS-depressed, PANSS-psychotic, and PANSS-positive subscales. Altered platelet MAO-B activity, controlled for the possible confounders, was associated with the development and severity of different symptoms occurring in PTSD. These findings confirmed the role of platelet MAO-B activity as a peripheral marker of various psychopathological symptoms.

Platelet studies in panic disorder: A review

Objective: The blood platelet has been proposed as a model of central neurons and may therefore be used as a peripheral marker of psychiatric illness. One method of investigating serotonin function in panic disorder has relied on the use of the platelet as a model of serotonergic neurons. This article reviews the studies of platelet function in panic disorder.

Method: A literature search and review of relevant papers was undertaken.

Result: Studies examining platelet serotonin uptake and concentration in panic disorder patients have to date yielded conflicting results, with some investigators reporting increased serotonin uptake, others reduced uptake. Similarly studies of platelet 3H-imipramine binding have also yielded conflicting results. Two studies of platelet 3H-paroxetine binding have shown a reduction in the density of binding sites (Bmax) in patients with panic disorder. Platelet monoamine oxidase activity in anxiety disorders has been reported to be increased by some investigators but decreased by others. Methodological considerations may have been responsible for these differences. Finally, studies of α2 adrenoceptor density have also produced contrasting findings.

Conclusion: The findings of these studies indicate that platelet function is altered in panic disorder. Such changes may allow an insight into the biochemical aetiology of the illness. Further studies are required to delineate the role of serotonin and non-adrenaline in panic disorder.

Similar calcification process in acute and chronic human brain pathologies

Cellular microcalcification observed in a diversity of human pathologies, such as vascular dementia, Alzheimer's disease, Parkinson's disease, astrogliomas, and posttraumatic epilepsy, also develops in rodent experimental models of central nervous system (CNS) neurodegeneration. Central to the neurodegenerative process is the inability of neurons to regulate intracellular calcium levels properly, and this is extensible to fine regulation of the CNS. This study provides evidence of a common pattern of brain calcification taking place in several human pathologies, and in the rat with glutamate-derived CNS lesions, regarding the chemical composition, physical characteristics, and histological environment of the precipitates. Furthermore, a common physical mechanism of deposit formation through nucleation, lineal growth, and aggregation is presented, under the modulation of protein deposition and elemental composition factors. Insofar as calcium precipitation reduces activity signals at no energy expense, the presence in human and rodent cerebral brain lesions of a common pattern of calcification may reflect an imbalance between cellular signals of activity and energy availability for its execution. If this is true, this new step of calcium homeostasis can be viewed as a general cellular adaptative mechanism to reduce further brain damage.

Neurobiology of generalized anxiety disorder

On reviewing the literature on GAD and trying to summarize the various developments in the field of neurobiology of GAD, we see that a range of hypotheses try to explore and integrate the observations found into potentially meaningful theories. Abnormal serotonergic and GABAergic function occur in many patients with GAD. Functional imaging data have shown increased cortical activity and decreased basal ganglia activity in patients with GAD, which reverses with treatment, but it is apparent that no one theory is sufficiently comprehensive to propose a unitary hypothesis for the development of GAD and other anxiety disorders. GAD is a relatively new diagnosable condition, first introduced into the classification system of psychiatric disorders in 1980, and since then has undergone a series of changes in its conceptualization, with some investigators questioning the existence of the condition as a distinct entity. Any inferences that may be drawn from various studies must be guarded, and it is appropriate to compare studies using the same diagnostic criteria. Significant research has been done and may lead to exciting new discoveries in the treatment of anxiety disorders in general and GAD in particular. Gray's model of behavioral inhibition, in which the septohippocampal system acts by assessing stimuli for the presence of danger and, when that is detected, activates the behavioral-inhibition circuit, provides a neuroanatomic conceptualization that has been expanded by preclinical research. Some exciting work has been done on CRF and the concept of development, vulnerability, and kindling and some investigators have contributed to this area of interest. This concept supports the hypothesis that a genetic predisposition, coupled with early stress, in the crucial phases of development may result in a phenotype that is neurobiologically vulnerable to stress and may lower an individual's threshold for developing anxiety or depression on additional stress exposure. The pharmaceutical industry is exploring treatment options using CRF antagonists, and research on other neuropeptides, especially NPY, will be of interest. Research on neurosteroids also may bring the opportunity for pharmacologic treatment approaches. Future research on the startle reflex and on the NMDA and the metabotropic glutamate receptors is important. Future studies of a more homogenous patient population and using more sophisticated techniques, such as molecular genetic strategies and better imaging techniques, may answer some of the outstanding questions.

Season of birth in panic disorder

Several studies have investigated the seasonal distribution of the birth dates of patients with psychiatric diseases. Our purpose was to verify if there is a specific distribution (by month) of birth dates in subjects with panic disorder (PD). The birth dates of 843 outpatients with a diagnosis of PD were compared with those of 1,181 subjects with other mental diseases. The birth dates of psychiatric patients were compared to those of the general Tuscane and Italian populations. The monthly distribution of birth in patients with PD (with and without comorbidity) peaked in September to December, while no relevant deviation in birth rate was observed in other mental diseases. Our results suggest a pathogenic role of birth seasonality in the development of PD.

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.

Borderline personality, impulsiveness, and platelet monoamine measures in bulimia nervosa and recurrent suicidal behavior

This study examined the relationship between borderline and impulsive personality traits on the one hand, and monoamine function on the other in 15 women with bulimia nervosa and 15 women with recurrent suicidal behavior. Platelet serotonin (5-HT) and platelet monoamine oxidase (MAO) activity were used as peripheral measures of monoaminergic function. All suicide attempters were diagnosed as having a borderline personality disorder, whereas this diagnosis was less frequent in bulimics. Bulimics with borderline comorbidity resembled recurrent suicide attempters with borderline personality disorder more closely in both psychological (anger, impulsive behavior) and biochemical characteristics (platelet 5-HT) than bulimics without borderline personality disorder. Platelet 5-HT was higher in patients with borderline personality than in normal female controls and was positively correlated with the disposition to experience anger. Impulsive personality traits were consistently negatively correlated with platelet MAO activity. Our findings support the subdivision of bulimics according to the presence of borderline or "multi-impulsive" personality disorder.

Growth hormone response to apomorphine in panic disorder: comparison with major depression and normal controls

Several lines of evidence suggest that dopamine might be involved in anxiety states. In the present study we assessed the growth hormone (GH) response to 0.5 mg apomorphine (a dopaminergic agonist) in 10 male drug-free inpatients meeting Research Diagnostic Criteria for panic disorder who were compared with 10 male major depressive inpatients and 10 male normal controls. The three groups differed significantly in the GH peak response (mean +/- SD): 27.8 +/- 12.5 ng/ml in panics, 5.4 +/- 4.0 ng/ml in major depressives, and 25.8 +/- 11.3 ng/ml in normal controls (F(2,27) = 15.3; P = 0.00003). Although there were significant differences between panics and major depressives (P = 0.00004), and between major depressives and controls (P = 0.00004), panics did not significantly differ from controls. These results do not support the hypothesis of an overlap between panic and affective disorders, and suggest that the hypothalamo-GH-somatomedin axis could be intact in panic disorder.

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.

A kinetic analysis of platelet monoamine oxidase activity in patients with panic attacks

A kinetic analysis of platelet monoamine oxidase (MAO) was performed in 22 patients with panic disorder and 14 normal controls, using tyramine as a substrate. Patients and controls did not differ significantly for either Km or Vmax, when same sex contrasts were carried out. The results do not support some studies that have shown elevated MAO activity in patients with panic attacks. The reasons for the discrepancies between previous studies and the present one are explored.

Systemic hormonal and physiological abnormalities in anxiety disorders

Among the studies of systemic hormonal and physiological abnormalities associated with anxiety disorders, the most consistent and extensive findings suggest (a) peripheral adrenergic hyperactivity (including increases in norepinephrine but not epinephrine) and functional dysregulation, (b) increased incidence of mitral valve prolapse in panic patients, and (c) normal suppressibility of the hypothalamic-pituitary-adrenal cortical endocrine system with dexamethasone in panic patients. Other less-certain findings include (a) increased circulating concentrations of plasma ACTH and/or cortisol, and prolactin, in panic patients, (b) increased platelet monoamine oxidase activity in generalized anxiety and/or panic patients, (c) decreased gonadal axis activity in some anxious individuals, (d) decreased nighttime melatonin plasma concentrations in panic patients, and (e) peripheral alpha 2 and beta-adrenoreceptor down-regulation, with normal serotonin binding parameters. These findings, taken together, provide tentative support for dysfunction in adrenergic and GABAergic central nervous system mechanisms in people with anxiety disorders. Abnormal anxiety and normal stress both show evidence of adrenergic hyperactivity; however, there appear to be differences in hormonal profiles, especially the apparent lack of increase of epinephrine during panic attacks, as well as differences in the reactivity of the system, and in the "trigger" mechanisms which determine when the response occurs.

Platelet monoamine oxidase activity in panic disorder

Platelet monoamine oxidase (MAO) activity was studied in 21 patients meeting Research Diagnostic Criteria for panic disorder and in 12 healthy controls. Platelet MAO activity in females in both patient and control groups tended to be higher than that in males, but the results did not reach statistical significance. Platelet MAO activity was significantly decreased in panic disorder patients compared to controls.

Mitral valve abnormalities and catecholamine activity in anxious patients

We studied 38 anxiety disorder patients, 19 of whom had evidence of mitral valve abnormalities by two-dimensional echocardiography. The presence or absence of mitral valve abnormalities was not related to 3-methoxy-4-hydroxyphenylglycol/creatinine excretion, platelet and plasma monoamine oxidase-type activity, or autonomic arousal as measured by blood pressure and resting heart rate. These findings fail to support the hypothesis that mitral valve abnormalities identify a specific subpopulation of anxious patients with differences in catecholamine function.