Serum Amyloid β Oligomer May Predict Treatment Response in Middle-Aged and Late-Life Patients With Depression.

AIM: Late-life patients with depression are reportedly less responsive to antidepressant treatment than younger patients. Additionally, patients who have depression comorbid with Alzheimer's disease (AD) and those with an amyloid β (Aβ) burden have shown a poor response to antidepressant treatment, suggesting that AD pathology may contribute to treatment resistance. A recent report indicated that Aβ oligomers in blood have increased in patients with AD and are associated with AD pathology. This study was performed to reveal the relationship between blood Aβ oligomers and the response to antidepressant treatment in middle-aged and late-life patients with depression. METHODS: In this observational study, serum levels of Aβ40, Aβ42, and Aβ oligomers were evaluated in 80 inpatients with major depressive disorder aged ≥ 40 years. Depressive symptoms were assessed at admission (baseline) and after 4 weeks of treatment. RESULTS: There were significantly fewer treatment responders among patients with than without serum Aβ oligomers (p = 0.016). Serum Aβ oligomers were found to influence the treatment response even after control for age, sex, number of depressive episodes, severity of depression, and Mini-Mental State Examination scores (p = 0.031). CONCLUSIONS: These results suggest that serum Aβ oligomers may predict a poor response to antidepressant treatment in middle-aged and late-life patients with depression. Our findings also lead us to speculate that elderly patients with a poor treatment response may share AD-related pathophysiological features or neural vulnerability.