Hippocampal volume in geriatric depression

Altered dendritic spine density in animal models of depression and in response to antidepressant treatment

Olfactory bulbectomy, neonatal clomipramine administration, and maternal deprivation have been employed as animal models of depression. Each model is unique with respect to the experimental manipulations required to produce "depressive" signs, expression and duration of these signs, and response to antidepressant treatments. Dendritic spines represent a possible anatomical substrate for the enduring changes seen with depression and we have previously shown that chronic antidepressant drug exposure alters the density of hippocampal dendritic spines in an enduring fashion. The purpose of the present study was to determine whether persistent alteration of hippocampal spine density is a common element in each of these different models of depression and whether such alterations could be reversed with chronic antidepressant treatment. The results show that olfactory bulbectomy reduced spine density in CA1, CA3, and dentate gyrus compared to sham-operated controls. Chronic treatment with amitriptyline, a tricyclic antidepressant, reversed the bulbectomy- induced reduction in dendritic spine density in CA1, CA3, and dentate gyrus, whereas treatment with mianserin, an atypical antidepressant, reversed this reduction only in dentate gyrus. On the other hand, neither neonatal clomipramine administration nor maternal deprivation affected hippocampal dendritic spine density. Repeated neonatal handling, however, as a control or as part of the maternal deprivation procedure, elevated spine density in dentate gyrus. These data suggest that long-lasting alterations in hippocampal dendritic spine density contribute to the neural mechanism underlying the olfactory bulbectomy model of depression, but not the neonatal clomipramine or maternal deprivation models.

Prenatal exposure to ethinylestradiol elicits behavioral abnormalities in the rat

Pregnant rats were i.p. injected with a solution of 17alpha-ethinylestradiol (15 microg kg(-1)) every day between day 9 and day 14 of pregnancy and the behavior of the offspring was compared to that of rats born from dams injected with the vehicle only during the same gestational period. The percentage of neonatal death was dramatically high in the prenatally treated group. Growth of the surviving animals was even better than that of controls, but when adult, they exhibited a number of behavioral abnormalities: increased spontaneous motor activity, decreased exploratory behavior, impaired cognitive processing, qualitatively different exploratory drive, and/or persevering behavior, increased anxiety-like behavior and social neophobia. These behavioral alterations, which resemble a number of psychiatric syndromes, suggest that ethinylestradiol altered the ontogenesis of different parts of the central nervous system involved in cognitive and emotional processes. However, it cannot be excluded that the changes in behavior of ethinylestradiol exposed offspring were due to the abnormal maternal behavior of the estradiol treated dams.

Longitudinal MRI study of hippocampal volume in trauma survivors with PTSD

OBJECTIVE

The authors prospectively explored whether a reduction in the volume of the hippocampus occurs in recent trauma survivors who develop posttraumatic stress disorder (PTSD).

METHOD

Thirty-seven survivors of traumatic events were assessed within a week of the traumatic event and 6 months later. The assessment included magnetic resonance imaging of the brain (including 124 coronal slices of 1.5-mm thickness), psychometric testing, and structured clinical interviews. The Clinician-Administered PTSD Scale conferred PTSD diagnoses at 6 months.

RESULTS

Ten subjects (27%) had PTSD at 6 months. The subjects with PTSD did not differ from those without PTSD in hippocampal volume (right or left) at 1 week or 6 months. There was no reduction in hippocampal volume in the PTSD subjects between 1 week and 6 months.

CONCLUSIONS

Smaller hippocampal volume is not a necessary risk factor for developing PTSD and does not occur within 6 months of expressing the disorder. This brain abnormality might occur in individuals with chronic or complicated PTSD.

The Hypothalamic-Pituitary-Adrenal Axis in Major Depressive Disorder: A Brief Primer for Primary Care Physicians

BACKGROUND: One of the most enduring and replicated findings in biological psychiatry is activation of the hypothalamic-pituitary-adrenal (HPA) axis in a subset of patients with major depressive disorder. This review will discuss some of these findings and their pertinence to the assessment and treatment of depressed patients. METHOD: MEDLINE, PsychINFO, and Current Contents databases were searched for pertinent articles on the HPA axis in patients with depression. In addition, hand searches were conducted of references from these sources and abstracts from meetings and books on this topic. Articles that would provide an overview of major or interesting studies in the field were selected for inclusion. RESULTS: The data support that HPA axis activation is common in depressed patients. Frequently reported findings include elevated cortisol and corticotropin-releasing hormone (CRH), nonsuppression on the dexamethasone suppression test, a blunted adrenocorticotropic hormone (ACTH) response to CRH, and hippocampal volume reduction. Evidence of HPA axis activation appears to have prognostic value and is associated with increased risk of depression relapse and even suicide. CONCLUSION: Future research in this area will focus on a better understanding of the etiology and long-term consequences of HPA axis activation in depressed patients. In addition, medications that act on the HPA axis are currently in development and may be part of the psychiatrist's and primary care physician's pharmacopoeia in the near future.