Postmortem monoamine receptor and enzyme studies in suicide

Biochemical effects of antidepressant treatment--studies of monoamine metabolites in cerebrospinal fluid and platelet [3H]imipramine binding

Two putative markers of serotonergic function, the concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and the binding parameters of [3H]imipramine to blood platelets, are discussed. Pretreatment concentrations of 5-HIAA in the cerebrospinal fluid (CSF) are lower in depressed patients than in normal controls, and a low concentration of the metabolite is associated with an increased risk of suicide. Many studies have attempted to use pretreatment concentrations of 5-HIAA, of the noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) and of the dopamine metabolite homovanillic acid (HVA) as predictors of therapeutic effect. On the whole, HVA appears to predict the effects of diverse treatments rather better than 5-HIAA. Treatment with antidepressant drugs changes the amine metabolite concentrations in the CSF in a relatively predictable way. Thus, administration of selective inhibitors of serotonin uptake has a more profound effect on CSF 5-HIAA, while noradrenaline uptake inhibitors preferentially reduce CSF MHPG concentrations. The Bmax of [3H]imipramine binding to blood platelets has been found to be lower in untreated depressed patients than in healthy controls in several studies. In a study from our group, three weeks' treatment with the serotonin uptake blockers zimeldine and alaproclate increased Bmax, while neither nortriptyline nor electroconvulsive treatment caused any change in Bmax after this time period. One year after initiation of treatment, patients who had clinically recovered and were no longer taking drugs still had a low Bmax of [3H]imipramine platelet binding. Prophylactic lithium caused a significant, but transient decrease in the Bmax of platelet [3H]imipramine binding in euthymic bipolar patients.

More tryptophan hydroxylase in the brainstem dorsal raphe nucleus in depressed suicides

Deficient serotonin neurotransmission in suicide is indicated by reduced brainstem serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), fewer 5-HT(1A) autoreceptors and reduced cortical serotonin transporter binding in suicide victims. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of 5-HT, and alterations in TPH could explain some of these findings. We sought to determine the amount of TPH immunoreactivity (TPH-IR) in the dorsal (DRN) and median (MRN) raphe nuclei in suicides and controls. Brainstems of suicide victims and controls (n = 11 pairs) were collected at autopsy, matched for age, sex and postmortem interval, frozen and sectioned (20 microm). Immunoautoradiography, using an antibody to label TPH, was performed, slides exposed to film and autoradiograms quantified by a computer-based image analysis system. We examined sections every 1000 microm throughout the whole length of the nucleus, performing statistical analysis only on those subjects for whom the raphe was complete (n = 8 pairs). TPH-IR (microCi/g) was higher in suicides than controls (S: 300.8 +/- 70.8 vs. C: 259.6 +/- 40.7, t = 2.57, df = 7, P = 0.04) in the dorsal raphe nucleus (DRN), and not different between suicides and controls (S: 251.3 +/- 44.2 vs. C: 235.9 +/- 27.4, t = 1.49, df = 7, P = 0.18) in the MRN. DRN TPH-IR was higher in male suicide victims (MS) compared to male controls (MC; MS: 318.4 +/- 54.4 vs. MC: 271.9 +/- 22.5, t = 2.66, df = 6, P = 0.03). The analysis of TPH-IR area and density at each DRN rostrocaudal levels showed higher area and density in suicides compared to controls in the rostral DRN and lower area and density in the caudal DRN. TPH-IR, an index of the amount of TPH enzyme, in the DRN is higher in depressed suicides. More TPH may be an upregulatory homeostatic response to impaired serotonin release or less autoreceptor activation. Alternatively, the serotonin impairment in suicide may be due to hypofunctional serotonin-synthesizing enzyme.

Frontotemporal dementia

Frontotemporal dementia is a new name for clinical Pick's disease; the eponymic term PiD has been increasingly restricted to the pathologic variant with Pick bodies. This article describes the clinical picture, pathology, and genetic mechanisms of frontal lobe dementia. Frontotemporal dementia is still under-diagnosed and underestimated, partly because the individual components of the complex are considered separately or are considered "heterogeneous," a somewhat misleading adjective used in many descriptions. This article emphasizes the considerable overlap among the different varieties of frontotemporal dementia, as well as the distinctive features of each.

Imaging of the serotonergic system: interactions of neuroanatomical and functional abnormalities of depression

For nearly three decades, evidence supporting a role for aberrant serotonergic function in the pathogenesis of depression has accumulated; however, only recently have methodologies and radiotracers suitable for in vivo clinical assessment of depression become available. To date, only a few neurochemical imaging studies have been performed in actively depressed subjects. A preliminary study using single photon emission computed tomography (SPECT) has demonstrated decreased levels of serotonin (5-HT) transporters in the midbrain regions of subjects with major depression. Analysis of the 5-HT2 receptor using positron emission tomography (PET) has suggested that this receptor may not be altered significantly in the depressed brain but may increase in response to antidepressant treatment. These findings are supported by studies in secondary "poststroke" depression that have shown that elevations in 5-HT2 receptor density correlated with the alleviation of symptoms of depressed mood. With the rapid development of novel PET and SPECT radiotracers, future studies of the serotonergic system that evaluate presynaptic (5-HT transporter) and postsynaptic (5-HT1A and 5-HT2A receptors) markers and the interaction of synaptic levels of 5-HT with these sites will make profound contributions to the understanding of the role of the serotonergic synapse in the pathophysiology of depression.

Suicidal behavior is attenuated in patients with multiple sclerosis by treatment with electromagnetic fields

A marked decrease in the levels of serotonin (5-HT) and its metabolite (5-HIAA) has been demonstrated in postmortem studies of suicide victims with various psychiatric disorders. Depression is the most common mental manifestation of multiple sclerosis (MS) which accounts for the high incidence of suicide in this disease. CSF 5-HIAA concentrations are reduced in MS patients and nocturnal plasma melatonin levels were found to be lower in suicidal than in nonsuicidal patients. These findings suggest that the increased risk of suicide in MS patients may be related to decreased 5-HT functions and blunted circadian melatonin secretion. Previous studies have demonstrated that extracerebral applications of pulsed electromagnetic fields (EMFs) in the picotesla range rapidly improved motor, sensory, affective and cognitive deficits in MS. Augmentation of cerebral 5-HT synthesis and resynchronization of circadian melatonin secretion has been suggested as a key mechanism by which these EMFs improved symptoms of the disease. Therefore, the prediction was made that this treatment modality would result in attenuation of suicidal behavior in MS patients. The present report concerns three women with remitting-progressive MS who exhibited suicidal behavior during the course of their illness. All patients had frequent suicidal thoughts over several years and experienced resolution of suicidal behavior within several weeks after introduction of EMFs treatment with no recurrence of symptoms during a follow-up of months to 3.5 years. These findings demonstrate that in MS pulsed applications of picotesla level EMFs improve mental depression and may reduce the risk of suicide by a mechanism involving the augmentation of 5-HT neurotransmission and resynchronization of circadian melatonin secretion.

Relationship between alpha 2-adrenergic function and suicidal behavior in depressed patients

The current main neurochemical theories of the biological correlates of suicidal behavior involve serotonergic and, to a lesser extent, dopaminergic systems. Few data are available about the possible implication of the noradrenergic function. In the present study, we assessed the growth hormone response to clonidine, a selective alpha 2-adrenergic agonist, in 15 DSM-III-R major depressive inpatients with a history of suicide attempts, compared with 15 age- and gender-matched major depressive inpatients without a history of suicidal behavior. Mean (+/- SD) growth hormone peak responses to clonidine were significantly lower in the group of suicide attempters than in the control group: 2.93 +/- 3.01 ng/ml vs. 8.28 +/- 8.15 ng/ml. Therefore, these results suggest that a blunted growth hormone response to clonidine could be a biological correlate of suicidal behavior.

Nocturnal melatonin secretion in suicidal patients with multiple sclerosis

Multiple sclerosis (MS) is characterised by the occurrence of patchy CNS demyelinating lesions, leading to various degrees of motor, sensory, affective, and cognitive deficits. MS is associated also with an increased risk of suicide accounting for a substantial rate of death among these patients. Post-mortem studies in suicide victims with various psychiatric disorders demonstrate a decreased concentration of serotonin (5-HT) and its metabolites in the brain. Since 5-HT is a precursor in the synthesis of melatonin and as pineal melatonin content was found to be low in suicide victims, we predicted lower melatonin secretion in suicidal versus non-suicidal MS patients during an acute exacerbation of symptoms. To test this hypothesis, we investigated nocturnal plasma melatonin levels in a cohort of 28 relapsing patients who were admitted consecutively to an inpatient Neurology service, 6 of whom had a history of suicide attempts and were having suicidal ideation at the time of admission. While both cohorts of patients were not distinguishable on any of the demographic data including use of psychotrophic drugs on the day of admission to hospital, the mean melatonin level in the suicidal group was significantly lower than in the control group (19.0 pg/ml +/- 11.9 versus 45.5 pg/ml +/- 27.1; p < .05). These findings support the prediction of the study implicating the pineal gland in the pathogenesis of suicidality in MS and reinforce the concept that a biological rather than a reactive etiology underlies the development of psychiatric symptoms in MS.

5-HT uptake sites and 5-HT2 receptors in brain of antidepressant-free suicide victims/depressives: increase in 5-HT2 sites in cortex and amygdala

The density (Bmax) of 5-HT2 receptors labelled with [3H]ketanserin was significantly increased in prefrontal cortex (by 67%) and amygdala (by 97%) from suicide/depressives in comparison with controls. There were no differences in Kd of [3H]ketanserin binding between the two groups. The density (Bmax) and affinity (Kd) of [3H]paroxetine sites were not significantly different in the suicide/depressives and controls. The ratio between the density of presynaptic 5-HT uptake sites and postsynaptic 5-HT2 receptors in amygdala was significantly lower in suicide/depressives than in controls. The data confirm and extend some of the previous findings of increases in 5-HT2 receptors in post-mortem brains of suicide victims and depressives who died of natural causes and lend support to the view that an abnormality in brain serotonergic system is associated with depression and suicidal behaviour.

Suicidal behavior and growth hormone response to apomorphine test

Several cerebrospinal fluid (CSF) studies have provided support for a possible role for the dopaminergic system as a biological correlate of suicidal behavior. Indeed, low CSF levels of the dopamine metabolite homovanillic acid (HVA) have been described in depressed patients with a history of suicide attempts. In this study, we assessed the dopamine receptor sensitivity in relationship to suicidal behavior by measuring growth hormone (GH) response to apomorphine 0.5 mg subcutaneously (sc) in 15 DSM-III-R (APA 1987) major depressive inpatients with a history of suicide attempts, compared to age-matched and gender-matched major depressive inpatients without a history of suicide. Patients with a history of suicidal behavior exhibited a significantly lower GH response to apomorphine than patients who never attempted suicide (t = 3.60, df = 1.28, p = 0.0012). Therefore, these results suggest that a blunted GH response to apomorphine could represent a biological marker of suicidal behavior.

Altered pineal serotonin binding in some suicides

Serotonergic abnormalities have been regularly reported in the brains of suicide victims. Because of evidence that pineal function is altered in depressed subjects and that serotonin-releasing axons may innervate the pineal, we assayed tritiated serotonin binding in a series of control and suicide pineals. High affinity binding was present, and there were apparent differences between some suicides and controls.

Suicide: a guide to risk factors, assessment, and treatment of suicidal patients

This article summarizes what is known about risk factors for suicide in both adolescent and adult populations. It also translates this knowledge base into practical considerations for the physician on the assessment and treatment of suicidal patients. Since most patients who commit suicide have seen a physician in the weeks to month prior to their deaths, and many kill themselves with medications prescribed by their doctors, the physician's early detection and treatment of suicidal behaviors and associated psychiatric disorders in his or her patients becomes a major suicide prevention strategy.