Decreased brainstem and putamen SERT binding potential in depressed suicide attempters using [11C]-zient PET imaging

BACKGROUND

Deficits in serotonergic neurotransmission have been implicated in the pathogenesis of depression and suicidality. The present study utilized a novel positron-emission tomography (PET) ligand to quantitate and compare brain regional serotonin transporter (SERT) binding potential in depressed patients with a past history of suicide attempts to that of healthy comparison subjects.

METHOD

We used [(11) C]-ZIENT PET to label SERT in the serotonergic cell body rich brainstem, and forebrain projection fields. Quantitative PET emission data from 21 adults (10 healthy controls and 11 drug-free patients with major depression) was used for group comparison. SERT binding potential (BPND ) in eight MRI-based brain regions of interest (ROI) were compared in high-resolution PET images.

RESULTS

SERT binding potential was significantly decreased in the midbrain/pons (P = .029) and putamen (P = .04) of depressed patients with a past suicide attempt relative to comparison subjects. Forebrain SERT binding was also reduced in the patient sample, though these region effects did not survive a multiple comparison correction.

CONCLUSION

These results suggest that decreased availability of the brainstem and basal ganglia SERT represents a biomarker of depression and thus confirm and extend the role of dysregulation of brain serotonergic neurotransmission in the pathophysiology of depression and suicide.

Compartmental modeling of 11C-HOMADAM binding to the serotonin transporter in the healthy human brain

The novel PET radioligand (11)C-N,N-dimethyl-2-(2'-amino-4'-hydroxymethylphenylthio)benzylamine ((11)C-HOMADAM) binds with high affinity and selectively to the serotonin transporter (SERT). The purpose of this study was to develop a reliable kinetic model to describe the uptake of (11)C-HOMADAM in the healthy human brain.

METHODS

Eight volunteers participated in the study; 5 of them were fitted with arterial catheters for blood sampling and all were scanned on a high-resolution research tomograph after the injection of (11)C-HOMADAM. Regional distribution volumes and binding potentials were calculated with 2- and 4-parameter arterial-input compartment models, a 3-parameter reference tissue compartment model, and the Logan graphic approach.

RESULTS

The 2-parameter arterial-input compartment model was statistically superior to the 4-parameter model and described all brain regions. Calculated binding potentials agreed well between the arterial-input model and the reference tissue model when the cerebellum was used as the reference tissue. The Logan graphic approach was not able to estimate the higher concentration of SERT in the dorsal raphe than in the midbrain.

CONCLUSION

(11)C-HOMADAM is a highly promising radioligand with high ratios of specific binding to nonspecific binding in known SERT-rich structures, such as the raphe nuclei. The 3-parameter reference tissue model approach permits a simplified quantitatively accurate method for estimating SERT binding potentials.

The dexamethasone/corticotropin-releasing factor test in men with major depression: role of childhood trauma

BACKGROUND

The dexamethasone/corticotropin-releasing factor (CRF) test is considered to be the most sensitive measure of hypothalamic-pituitary-adrenal (HPA) axis hyperactivity and has been demonstrated to be altered in patients with major depression (MDD). Although childhood trauma is a demonstrated risk factor for MDD and patients with a history of childhood abuse and MDD demonstrate HPA axis hyperactivity, the dexamethasone/CRF test remains unstudied in this population. We determined the impact of childhood trauma on dexamethasone/CRF test results in patients with MDD.

METHODS

Forty-nine healthy men, ages 18-60 years, without mania or psychosis, active substance abuse, or eating disorder and medication-free were recruited into four study groups, including: 1) normal subjects with no childhood abuse history or psychiatric disorder (n = 14); 2) men with childhood abuse histories without current MDD (n = 14); 3) men with childhood abuse histories with current MDD (n = 15); and 4) men with current MDD and no childhood abuse history (n = 6). Plasma adrenocorticotropin (ACTH) and cortisol concentrations were measured in response to dexamethasone/CRF administration.

RESULTS

Men with childhood trauma histories exhibited increases in ACTH and cortisol responses to dexamethasone/CRF compared with non-abused men. In particular, abused men with current MDD showed increased responsiveness compared with control subjects and depressed men without childhood abuse experience. Increased response was associated with the severity, duration, and earlier onset of the abuse. The effects were not explained by concurrent posttraumatic stress disorder.

CONCLUSIONS

Childhood trauma increases HPA axis activity as measured with the dexamethasone/CRF test in adult men with MDD, potentially reflecting environmental risk for developing depression.

Ethnic differences in patterns of suicide across the life cycle

OBJECTIVE

The authors analyzed suicide across the life cycle of different ethnic groups in an urban population equally divided between blacks (44.6%) and whites (48.1%).

METHOD

Two data sets were used: 1) all suicides in Fulton County, Ga., from January 1994 through December 2002 and 2) all U.S. suicides reported by the National Center for Injury Prevention in 1999 and 2000.

RESULTS

The population rates for suicide in Fulton County were 1.22 per 100,000 black females, 10.74 per 100,000 black males, 9.89 per 100,000 white females, and 21.04 per 100,000 white males. In Fulton County, age at completed suicide was more than a decade lower in blacks than in whites. The median age of black victims was 32 years, with an interquartile range (IQR) of 23-45, and the median for whites was 44 years (IQR=31-58); the difference was significant. The mean ages of victims who were black (mean=36.1 years, SD=17.0) and of "other" race (mean=35.7, SD=14.3) were significantly lower than the mean for whites (mean=46.2, SD=18.5). The national data were similar, but minorities accounted for an even smaller percentage of suicides. Median age at completed suicide for African Americans nationally was 34 years (IQR=24-45) compared to 44 years (IQR=32-58) for Caucasians.

CONCLUSIONS

African Americans commit suicide at rates much lower than those for whites, but they do so when much younger and they have a narrow, age-defined window of vulnerability. Age-specific psychopathological processes and protective factors may define suicide risk for each demographic group.

Reduction of episodes of seclusion and restraint in a psychiatric emergency service

The authors developed a comprehensive plan focusing on the early identification and management of problematic behaviors in an effort to reduce seclusion and restraint in a psychiatric emergency service and to increase adherence to hospital standards for its use. Hospital data for nine months before and nine months after the implementation of the plan were retrospectively reviewed. Two key factors that were believed to increase the likelihood of episodes of seclusion and restraint were ineffectual management of problematic behavior and inadequate monitoring. The plan, when instituted, was associated with a 39 percent reduction of instances of seclusion and restraint. Compliance with hospital standards increased to 100 percent.

Cocaine use disorders and suicidal ideation

The goal of this study was to determine the contribution of substance abuse to the expression of suicidal ideation in a sample of patients referred for evaluation of chemical dependency in a large urban Psychiatric Emergency Service (PES). Records from 777 consecutive patients referred to the chemical dependency service of the PES were analyzed. Of this sample, 43.7% of the patients with only a cocaine use disorder expressed suicidal ideation compared to 38% of those with both cocaine and alcohol use disorders, 24.3% with only an alcohol use disorder and 17% with other drug use disorders (chi(2)=24.768; df=3; P<0.0001). More than half of the patients (55.26%) with a substance-induced mood or psychotic disorder expressed suicidal ideation (chi(2)=23.174, df=1, P<0.0001), and the majority (85%) of these patients had a cocaine use disorder (chi(2)=12.309, df=1, P<0.0005). In this sample of patients served by an urban PES, cocaine use is associated with suicidal ideation, more so than other substances of abuse.