Relationship between depressive symptom severity and amygdala volume in a large community-based sample.

Amygdala is an affective processing center that regulates and assigns valence to different emotions and has been implicated in the pathophysiology of mood disorders. This population-based study employed a community sample of 1747 adults to examine relationships between amygdala volume and depressive symptom severity. Neuroimaging data from participants in the Dallas Heart Study were used. Magnetic resonance images of right, left, and total amygdala volume were used as response variables in multiple regressions. Predictor variables included Quick Inventory of Depressive Symptomatology Self-Report (QIDS-SR) scores, intracranial volume, age, gender, race/ethnicity, body mass index, self-reported alcohol use, years of education, and psychotropic medication use. In the overall sample, QIDS-SR scores were not significantly related to left, right or total amygdala volume. A significant QIDS-SR by age interaction was observed, thus a follow-up subgroup analysis was conducted in age groups 18-39, 40-59, and ≥ 960. A significant negative relationship was observed between QIDS-SR scores and right and total, but not left, amygdala volume in the 18-39 age group but not in other age groups. Significant relationship between QIDS-SR scores and amygdala volume in young adults suggests possible biological differences in depressive symptoms in people of this age group.

Microtubule associated protein 2 in bipolar depression: Impact of pregnenolone.

BACKGROUND: Pregnenolone, and related neurosteroids, may have antidepressant properties. Preclinical research proposes that microtubule associated protein 2 (MAP2) binding may be a mechanism for antidepressant properties of pregnenolone. Thus, MAP2 might be a novel target for antidepressant therapy. This clinical study is the first to examine serum MAP2 levels in people with bipolar depression and controls, and whether pregnenolone treatment is associated with a change in MAP2 levels. METHODS: Blood samples from a previously published clinical trial of pregnenolone for adult bipolar depression were analyzed at baseline and week 6 of treatment with pregnenolone or placebo for serum MAP2 levels using Western Blot. MAP2 levels from healthy controls were also obtained. RESULTS: MAP2 levels in the bipolar depressed patients (n=11) tended to be higher than in controls (n=4) (p=0.062). MAP2 levels decreased non-significantly from baseline to week 6 in placebo (n=5) and pregnenolone-treated patients (n=6). MAP2 level changes correlated positively with change in self-reported depressive symptom scores in the pregnenolone group (r=0.771, p=0.072) but not in the placebo group (r=0.000, p=1.000). LIMITATIONS: This study, exploring relationships between MAP-2 in humans with mood disorders, is limited by the small sample size. Thus, the findings must be viewed with great caution. CONCLUSION: These findings suggest possible differences in serum MAP-2 levels between bipolar depressed persons and controls and a relationship between changes in depressive symptoms and MAP-2 levels during pregnenolone therapy. Findings suggest additional research is needed on MAP-2 in mood disorders.