Clinical course and serum amyloid ß levels in elderly patients with major depressive disorder.

ABSTRACT

BACKGROUND: Depression is known to be a risk factor for Alzheimer's disease (AD). Changes in amyloid ß protein (Aß) metabolism have been speculated as a factor contributing to the transition from depression to AD. The aim of this study is to reveal the time course and state-dependency of Aß metabolism. METHODS: Serum Aß levels in 277 elderly (≥60 years) patients with depression (both early- and late-onset) were measured at admission, immediately after remission, and 1 year after remission, and compared them with 178 healthy subjects. RESULTS: The analysis revealed decreased Aß42 levels and increased Aß42/40 ratios in elderly patients with depression at admission compared with healthy subjects. These changes in the acute phase of depression were not normalized immediately after remission; however, they recovered to healthy levels 1 year after remission. LIMITATIONS: There is a possibility that the results may be influenced by antidepressants. CONCLUSIONS: These results suggest that altered Aß metabolism caused by depression may ameliorate, although after a lengthy period of time after remission. Our findings also suggest that the AD-related pathological changes caused or increased by depression can be reduced by maintaining remission for an extended period of time.