Recovery from major depression is not associated with normalization of serotonergic function

BACKGROUND

Plasma prolactin response to fenfluramine, a serotonergic agent, is typically blunted in moderately to severely depressed adults when compared to healthy controls. It is not clear, however, whether this dysregulation represents an acute change during symptomatic depression or a chronic disturbance.

METHODS

In the current study, the prolactin responses to D,L-fenfluramine (weight-adjusted oral dose) of 29 adults who had a history of at least one major depressive episode (DSM-III-R criteria), but not during the past year, were compared to the prolactin responses of 58 age-, sex-, and socioeconomic status-matched adults without a lifetime history of major depression.

RESULTS

Individuals with a positive history of major depression had significantly lower peak prolactin responses than controls. This finding was not attributable to weight, fenfluramine bioavailability, or baseline prolactin levels.

CONCLUSIONS

This is the first investigation to compare men and women with a history of depression but not depressed at the time of the fenfluramine challenge to a similar group of healthy controls. The results are consistent with the hypothesis that central serotonergic activity is persistently disturbed in adults who experience depressive episodes.

Cocaine use associated with increased suicidal behavior in depressed alcoholics

The aim of this study was to determine whether depressed alcoholics who used cocaine would display a higher prevalence of suicidal behavior and suicidal ideation than depressed alcoholics who did not use cocaine. Forty-one depressed alcoholics participated in this prospective study of consecutively admitted inpatients. Seventeen patients (41.5%) had made a suicide attempt during their current depressive episode, and all but 1 of these attempts occurred during the week prior to their hospitalization. Ten patients used cocaine in the week prior to hospitalization, and 7 of these 10 (70%) had made a suicide attempt during that week. In contrast, only 32% of the depressed alcoholics who did not use cocaine made a suicide attempt during that week (p < .05). Suicidal ideation was also more prevalent in alcoholics who used cocaine. These data provide evidence that cocaine use is associated with an increased prevalence of suicidal behavior and suicidal ideation in depressed alcoholics.

Assessing the observed relationship between low cholesterol and violence-related mortality. Implications for suicide risk

Health advocacy groups advise all Americans to restrict their dietary intake of saturated fat and cholesterol as an efficacious and safe way to lower plasma cholesterol concentrations and thus reduce the risk of coronary heart disease and other atherosclerotic disorders. However, accumulating evidence suggests that naturally low or clinically reduced cholesterol is associated with increased nonillness mortality (principally suicide and accidents). Other evidence suggests that such increases in suicide and traumatic death may be mediated by the adverse changes in behavior and mood that sometimes accompany low or reduced cholesterol. These observations provided the rationale for an ongoing series of studies in monkeys designed to explore the hypothesis that alterations in dietary or plasma cholesterol influence behavior and that such effects are potentiated by lipid-induced changes in brain chemistry. In fact, the investigations in monkeys reveal that reductions in plasma cholesterol increase the tendency to engage in impulsive or violent behavior through a mechanism involving central serotonergic activity. It is speculated that the cholesterol-serotonin-behavior association represents a mechanism evolved to increase hunting or competitive foraging behavior in the face of nutritional threats signaled by a decline in total serum cholesterol (TC). The epidemiological and experimental data could be interpreted as having two implications for public health: (1) low-cholesterol may be a marker for risk of suicide or traumatic death and (2) cholesterol lowering may have adverse effects for some individuals under some circumstances.

A synthesis of current findings regarding neurobiological correlates and treatment of suicidal behavior

Considerable progress has been made in the study of neurobiological correlates of suicidal behavior. These studies have confirmed the link between reduced serotonergic function and serious suicidal acts. They have localized the changes to the ventral prefrontal cortex and suggested how genetics, childhood rearing, alcoholism, substance abuse, gender, age, and cholesterol intake can modulate suicide rates through effects on the serotonergic system. Future studies need to apply this knowledge in the development of in vivo brain imaging and molecular genetic probes for study of high-risk patients. Identification of high-risk groups is essential for the conduct of controlled treatment trials, which are presently almost entirely lacking in suicidal populations. Previous clinical trials of medications and psychotherapies have targeted axis I or axis II disorders but not the predisposition to suicidal acts. Controlled treatment in high-risk patients must be undertaken to identify interventions that can reduce the propensity for suicidal acts. Such interventions will supplement current treatment strategies that target the associated psychiatric illness and reduce the opportunities to attempt suicide in high-risk patients by hospitalization.

Postmortem findings in suicide victims. Implications for in vivo imaging studies

Alterations in serotonergic and noradrenergic receptor binding in membrane homogenates from the brain of suicide victims suggest a biological substrate for the vulnerability to commit suicide. We and others have employed high-resolution quantitative autoradiography of full coronal sections of the prefrontal cortex to map the locus of maximal change in receptor binding. We found alterations in binding to the serotonin transporter, the 5-HT1A, and the 5-HT2A receptors primarily in the ventral and ventrolateral prefrontal cortex of suicide victims. Importantly, these changes are often modest in magnitude and anatomically restricted to one or two Brodmann areas. Furthermore, we have found that care in case selection is essential, because sex, age, drugs, and comorbid diagnoses contribute to receptor binding. The implications for in vivo imaging are considerable, directing the focus of such studies toward the ventrolateral prefrontal cortex. However, because ligands are limited, as is the resolution of current methods, including PET, automated analyses that produce statistical images, rather than manual selection of individual slices, will likely lack the ability to detect the discrete receptor changes found postmortem. Alternatively, the advantages of examining large numbers of subjects, imaging the entire brain, obtaining detailed clinical information in the living patient, and magnifying the changes with neuropharmacological challenges present a promising outlook for making major advances into the identification of brain abnormalities associated with suicide risk.

Characteristics of borderline personality disorder associated with suicidal behavior

OBJECTIVE

This study examined the relationship between characteristics of borderline personality disorder and suicidal behavior. The authors hypothesized that a specific feature of borderline personality disorder, impulsivity, and childhood trauma, a possible etiological factor in the development of impulsivity, would be associated with suicidal behavior.

METHOD

Information on lifetime history of suicidal behavior was obtained from 214 inpatients diagnosed with borderline personality disorder by structured clinical interview. The authors examined the relationship between DSM-III-R criteria met and the following measures of suicidal behavior: presence or absence of a previous suicide attempt, number of previous attempts, and lethality and intent to die associated with the most lethal lifetime attempt.

RESULTS

Impulsivity was the only characteristic of borderline personality disorder (excluding the self-destructive criterion) that was associated with a higher number of previous suicide attempts after control for lifetime diagnoses of depression and substance abuse. Global severity of pathology of borderline personality disorder was not associated with suicidal behavior. History of childhood abuse correlated significantly with number of lifetime suicide attempts.

CONCLUSIONS

The trait of impulsivity is associated with number of lifetime suicide attempts and may therefore be a putative risk factor for a future suicide attempt. If so, impulsivity is a potential target therapeutically for prevention of future suicide attempts. The association between childhood abuse and number of lifetime suicide attempts is consistent with the hypothesis that childhood abuse is an etiological factor in the development of self-destructive behaviors.

Subsensitivity of adenylyl cyclase-coupled receptors on mononuclear leukocytes from drug-free inpatients with a major depressive episode

Previous studies have demonstrated blunted beta-adrenergic responsivity in leukocytes from depressed patients. We sought to determine if this blunted cyclic adenosine monophosphate (AMP) response is specific for beta-adrenergic receptors (homologous), or whether other adenylyl cyclase-coupled receptors are also involved (heterologous), in order to localize this effect at the level of the receptor versus the coupling protein or the transducer, adenylyl cyclase. We studied adenylyl cyclase-mediated responses in peripheral blood mononuclear cells from 95 drug-free patients with a major depressive episode and 69 healthy controls. We found a similar degree of decrease in the peak cyclic AMP response to activation of the beta-adrenergic receptor (28%) and the prostaglandin receptor (34%) in the depressed patients, which indicated heterologous desensitization. Forskolin cyclic AMP responses were not blunted. Blunting of cyclic AMP responses to isoproterenol did not appear to correlate with levels of plasma norepinephrine and epinephrine or hypothalamic-pituitary-adrenocortical function. The absence of a decrease in the peak forskolin-generated cyclic AMP response, which involves direct activation of adenylyl cyclase, suggests an abnormality at the level of the coupling protein in these adenylyl-coupled receptors in depressed patients. Future studies need to determine whether this leukocyte signal transduction defect in depression also involves brain adenylyl cyclase-coupled receptors.

In vivo imaging of neurotransmitter systems using radiolabeled receptor ligands

In vivo functional brain imaging, including global blood flow, regional cerebral blood flow (rCBF), measured with positron emission tomography (PET) and single photon emission computed tomography (SPECT), and regional cerebral metabolic rate (rCMR) measured with deoxyglucose PET, have been widely used in studies of psychiatric disorders. These studies have found modest differences and required large numbers of patients. Activation studies using rCBF or rCMR as indices of neuronal activity are more sensitive because patients act as their own control; however, findings localize regions of change but provide no data about specific neurotransmitter systems. After a general discussion of the role of neurotransmitter systems in neuropsychiatric disorders, an overview of the methodology of development and selection of radioligands for PET and SPECT is presented. Studies involving PET and SPECT ligand methods are reviewed and their findings summarized, including recent work demonstrating successive mutual modulation of neurotransmitter systems. Kinetic and equilibrium analysis modeling are reviewed. The emerging methodology of measuring neurotransmitter release on activation, both pharmacologically and by task performance, using ligand methods is reviewed and proposed as a promising new approach for studying psychiatric disorders.

Possible association of a polymorphism of the tryptophan hydroxylase gene with suicidal behavior in depressed patients

OBJECTIVE

This study was designed to test the hypothesis that serotonin-system-related genes may be correlated with suicide risk.

METHOD

Fifty-one unrelated Caucasian inpatients with major depression, with or without a history of suicidal acts, were genotyped for a biallelic polymorphism at the tryptophan hydroxylase locus.

RESULTS

The less common tryptophan hydroxylase U allele occurred with greater frequency in the patients who had attempted suicide. A logistic regression analysis confirmed an association between tryptophan hydroxylase genotype and lifetime history of suicide attempts.

CONCLUSIONS

Serotonergic-system-related genes may influence the risk of suicide in persons with major depression.

Biologic alterations in the brainstem of suicides

This article reviews the data supporting the notion that there are alterations in serotonin and norepinephrine in the ventral prefrontal cortex and brainstem of suicide victims. Normal amounts of serotonin are found in terminal fields such as the dorsolateral prefrontal cortex, but serotonin responses are defective at least in the hypothalamus. Suicide victims appear to have fewer noradrenergic LC neurons, containing more of the tyrosine hydroxylase enzyme needed for transmitter synthesis. A failure of behavior restraint mechanisms involving the prefrontal cortex as a consequence of alterations in brainstem monoaminergic nuclei may result in a predisposition to suicidal behavior.

The functional neuroanatomy of mood disorders

Mood disorders may be associated with global and regional changes in cerebral blood flow and metabolism. The accumulated functional neuroimaging findings in mood disorders were reviewed in order to examine a proposed neuroanatomic model of pathophysiology. Global cerebral blood flow and glucose metabolism appear normal, but may be decreased in late-life depression. Regional cerebral blood flow and glucose metabolism deficits are present, and may be indicators of brain regions participating in neuroanatomic circuits involved in mood disorders. Decreased pre-frontal cortex blood flow and metabolism in depressed unipolar and bipolar patients are the most consistently replicated findings, and correlate with severity of illness. Basal ganglia abnormalities have been found in depressed unipolar and bipolar patients, involving decreased blood flow and metabolism. Temporal lobe abnormalities are present in bipolar disorder patients, and perhaps unipolar depression. There is conflicting evidence of abnormalities in other limbic regions. Cognitive impairment may correlate with decreased metabolism in frontal and cerebellar areas. The relationship between functional neuroimaging findings and clinical course, and therefore state and trait characteristics, has not been systematically investigated. Antidepressant medications, but not ECT, seem to reverse some of the identified functional brain changes in the depressed state. The structural, neurotransmitter and neuropathological correlates of these functional abnormalities are yet to be determined. Functional abnormalities in frontal, subcortical and limbic structures appear to be part of the pathophysiology of mood disorders.

Blunted serotonin response to fenfluramine challenge in premenstrual dysphoric disorder

OBJECTIVE

Indirect evidence suggests that abnormalities in serotonergic function may be involved in the pathogenesis of premenstrual dysphoric disorder. The goal of this study was to test the hypothesis of serotonergic deficiency in premenstrual dysphoric disorder by measuring the prolactin response to fenfluramine.

METHOD

The authors administered the serotonin-releasing drug dl-fenfluramine in a placebo-controlled protocol to nine women with premenstrual dysphoric disorder and 11 healthy female volunteers in the luteal phase of the menstrual cycle.

RESULTS

Compared to the normal subjects, the women with premenstrual dysphoric disorder had a significantly blunted prolactin response to fenfluramine.

CONCLUSIONS

Premenstrual dysphoric disorder appears to be associated with serotonergic deficiency.

Low use of neuroleptic drugs in the treatment of psychotic major depression

OBJECTIVE

The adequacy of pharmacologic treatment received by patients with psychotic major depression was evaluated.

METHOD

The authors systematically assessed the pharmacotherapy received by 187 depressed patients before initiation of ECT and compared the medication trials of those with psychotic (N = 53) and nonpsychotic (N = 134) depression.

RESULTS

Despite a median of four medication trials and median index episode duration of 20 weeks, only two (4%) of the patients with psychotic depression received at least one adequate pharmacotherapy trial. In contrast, 70 (52%) of the patients with nonpsychotic depression received at least one adequate trial. Twenty-five (47%) of the patients with psychotic depression received either no neuroleptic treatment (N = 11) or treatment for less than 3 weeks (N = 14). Only eight (15%) received a daily neuroleptic dose higher than 200 mg of chlorpromazine equivalents.

CONCLUSIONS

These findings suggest that many patients with psychotic major depression referred for ECT receive inadequate pharmacotherapy because of either the absence or the inadequate use of neuroleptic medication.

Comparison of cerebrospinal fluid monoamine metabolite levels in dominant-aggressive and non-aggressive dogs

Aggression has been shown to be related to reduced serotonergic activity in humans and non-human primates, and in rodents. We now studied the relationship between cerebrospinal fluid (CSF) monoamine metabolites and canine aggression in 21 dominant-aggressive dogs (Canis familiaris) and 19 controls. The diagnosis of dominance-related aggression was based upon a history of biting family members in contexts associated with dominance challenges. Post-mortem CSF 5-HIAA, MHPG and HVA were measured by high-performance liquid chromatography using electrochemical detection. Concentrations of CSF 5-HIAA (P = 0.01) and HVA (P < 0.001) were lower in the aggressive group (median values: 5-HIAA 202.0 pmol/ml; HVA 318.0 pmol/ml) than in controls (5-HIAA 298.0 pmol/ml; HVA 552.0 pmol/ml). No differences were noted in CSF MHPG levels. Differences in 5-HIAA were maintained after controlling for breed and age of dogs, but HVA differences may have been breed-dependent. Lower levels of 5-HIAA (P = 0.02) and HVA (P = 0.04) were found in the subgroup of aggressive dogs with a history of biting without warning (5-HIAA 196.0 pmol/ml; HVA 302.0 pmol/ml) compared to dogs that warned (5-HIAA 244.0 pmol/ml; HVA 400.0 pmol/ml). This study suggests that reduced serotonergic function is associated with aggressive behavior and impaired impulse control in dogs, a finding that is consistent with observations in primates, and suggests that serotonin modulates aggressive behavior throughout mammals.

Cerebrospinal fluid amines and higher-lethality suicide attempts in depressed inpatients

Previous studies have found that not all suicide attempters with major depression have reduced serotonergic activity based on low cerebrospinal fluid 5-hydroxyindoleacetic acid (CSF- 5-HIAA) levels. In this study we hypothesized that serotonergic function is lower in depressed patients who have carried out high-lethality suicide attempts resulting in more medical damage, which might explain differences in serotonergic activity among depressed suicide attempters. We assessed the relationship of CSF 5-HIAA and other amine metabolites to the most lethal lifetime suicide attempt in 22 drug-free inpatients with major depression. CSF 5-HIAA levels were lower in depressed patients with a history of a high-lethality or well-planned suicide attempt compared to depressed patients with a history of only low-lethality suicide attempt(s). Other CSF monoamine metabolites did not correlate with suicidal behavior. Low serotonergic activity may correlate with a predisposition to more lethal suicide attempts in major depression.

The anatomy of mood disorders--review of structural neuroimaging studies

The structural neuroimaging findings in mood disorders were reviewed, to evaluate evidence for a neuroanatomic model of pathophysiology, involving the prefrontal cortex, the basal ganglia, the amygdala-hippocampus complex, thalamus, and connections among these structures. Global atrophy is not consistently found. The best replicated finding is an increased rate of white matter and periventricular hyperintensities. A smaller frontal lobe, cerebellum, caudate, and putamen appear present in unipolar depression. A larger third ventricle, and smaller cerebellum and perhaps temporal lobe appear present in bipolar disorder. These localized structural changes involve regions that may be critical in the pathogenesis of mood disorders. Generalized and localized anatomic alterations may be related to age or vascular disease. The clinical and biological correlates of these changes need to be investigated to allow development of a more complete model of pathophysiology of mood disorders.

Attempted suicide characteristics and cerebrospinal fluid amine metabolites in depressed inpatients

BACKGROUND

Serotonin abnormalities have been reported in the brain of suicide victims. Evidence of a serotonin deficiency in suicide attempters is less consistent. We hypothesized that a serotonin deficiency may be present in suicide attempters whose attempt behavior more closely approximates completed suicide.

METHOD

Sixty-seven (67) drug-free depressed inpatients (46 suicide attempters, 21 nonattempters) underwent research clinical assessments and a lumbar puncture. Cerebrospinal fluid (CSF) monoamine metabolites were assayed. Degree of medical damage and intent of the most recent suicide attempt were rated.

RESULTS

CSF amine metabolites did not differentiate suicide attempters as a group from nonattempters. However, reduced serotonergic activity, as indicated by lower levels of CSF-5-hydroxyindoleacetic acid (5-HIAA) was associated with a history of planned suicide attempts and with suicide attempts that resulted in greater medical damage. Other monoamine metabolites did not correlate with seriousness of suicidal behavior, except for low CSF homovanillic acid and higher medical damage. No correlation was found with violent method.

CONCLUSIONS

Planned and more medically damaging suicide attempts appear to be associated specifically with low serotonergic activity and, therefore, resemble completed suicide both behaviorally and biochemically. It remains to be determined whether low levels of CSF 5-HIAA can predict greater medical damage in future suicide attempts.

Patterns of suicidality and alcohol use in alcoholics with major depression

The aims of this study were (1) to comprehensively characterize a population of alcoholics with major depression in a psychiatric hospital, (2) to determine the prevalence of suicidal behavior in this sample, and (3) to determine whether quantity of alcohol ingested was associated with level of suicidality. Ratings of drinking, depression, and suicidality were obtained using both self-rated and observer-rated instruments. The prevalence of suicide attempts in the week before hospitalization was remarkably high, approaching 40%, whereas 70% had made a suicide attempt at some point in their lifetime. These suicide attempts were typically impulsive in nature, involving little if any premeditation. Most subjects reported drinking more heavily than usual on the day of their suicide attempt. Recent suicidal behavior was significantly associated with recent very heavy drinking (< or = 70 drinks per week) and with number of drinks per drinking day. Quantity of drinking per drinking day was also significantly higher in those making a recent suicide attempt. However, no association was found between quantity of alcohol consumption and suicidal ideation. These findings suggest that recent heavy alcohol use primarily affects suicidality by increasing the likelihood of acting on suicidal ideation rather than by inducing suicidal ideation.

Validity of DSM-III-R diagnosis by psychological autopsy: a comparison with clinician ante-mortem diagnosis

Psychological autopsies are an important research tool in establishing risk factors associated with suicide. We report the results of a validity study comparing psychological autopsy-generated DSM-III-R diagnoses in suicides and non-suicides with chart diagnoses generated by clinicians who had treated the subjects prior to death. The Structured Clinical Interview for DSM-III-R Disorders (SCID-P) and the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID-II) were used to make independent post-mortem diagnoses. Comparison of research diagnoses with clinician ante-mortem diagnoses generated kappa coefficients of 0.85 for Axis I diagnoses and 0.65 for Axis II conditions. These kappa coefficients compare favourably with direct patient interview reliability studies. This provides evidence for the validity of the psychological autopsy as a method of determining psychiatric diagnosis.

Differential age-related loss of pigmented locus coeruleus neurons in suicides, alcoholics, and alcoholic suicides

We previously reported fewer locus coeruleus (LC) neurons in both suicide victims and alcoholics than among a group of nonpsychiatric controls. In the present paper we examine the rate of decline in the number of LC neurons with age, looking for possible differential rates among suicide victims, alcoholics, and controls. We also compare these groups with a group of alcoholics who died by suicide, and consider the effects of sex, race, and postmortem interval. LC neuron counts were obtained from a total of 32 subjects. In all groups, the number of neurons decreased with age, but by roughly age 40 the average LC count among the three suicide and/or alcoholic groups was lower than among controls. The rate of LC neuron loss was greater among suicides than among controls, but the rate of loss among alcoholics who were at least 30 years old was the same as that among the controls. Our group of alcoholic suicides had counts that were statistically indistinguishable from those of suicides. Differences among groups appear to be most pronounced in the middle third of the LC. Further studies are needed to determine the mechanisms of noradrenergic neuron loss and whether it is associated with an underlying major depression in suicide victims, or acquired after a period of excessive alcohol consumption.

Suicidal behavior in patients with major depression and comorbid personality disorders

We investigated the relationship of DSM-III-R personality disorder (PD) diagnoses and traits to suicidal behavior in patients with Major Depressive Disorder (MDD). Axis I and Axis II criteria and suicidal behavior were assessed using structured interviews of 102 psychiatric inpatients. Subjects with comorbid MDD and Borderline PD (BPD: n = 30) were more likely than other patients to have a history of multiple suicide attempts, and were equally likely to have made a highly lethal attempt. Number of BPD and other Cluster B (dramatic/erratic) criteria were better predictors of past suicidal behavior than were depressive symptoms. We conclude that patients with BPD symptomatology are at risk for serious suicide attempts. Moreover, severity of comorbid Cluster B PD psychopathology should be considered when assessing suicide risk in MDD patients even in those without a PD diagnosis.