Heterogeneity of elderly depression: increased risk of Alzheimer's disease and Aß protein metabolism.

Progress in neuro-psychopharmacology & biological psychiatry

PubMedID: 23276885

Namekawa Y, Baba H, Maeshima H, Nakano Y, Satomura E, Takebayashi N, Nomoto H, Suzuki T, Arai H. Heterogeneity of elderly depression: increased risk of Alzheimer's disease and Aß protein metabolism. Prog Neuropsychopharmacol Biol Psychiatry. 2013;43203-8.
Epidemiological studies have proposed that depression may increase the risk for Alzheimer's disease (AD), even in patients with early-onset depression. Although metabolism of amyloid ß protein (Aß) in elderly depression received attention in terms of their correlation, there is a serious heterogeneity in elderly depression in terms of age at onset of depression. Moreover, it is unknown whether early-onset major depressive disorder (MDD) has a long-term effect on the involvement of Aß metabolism and later development of AD. Thus, we evaluated serum Aß40 and Aß42 levels, the Aß40/Aß42 ratio in 89 elderly (=60 years of age) inpatients with MDD and 81 age-matched healthy controls, and compared them among patients with early-onset (<60 years) and late-onset (=60years) MDD and controls. The results showed that the serum Aß40/Aß42 ratio was significantly higher in patients with both early- and late-onset MDD than in controls (early-onset, p=0.010; late-onset, p=0.043), and it is of great interest that the serum Aß40/Aß42 ratio was negatively correlated with the age at MDD onset (R=-0.201, p=0.032). These results suggest that an earlier onset of MDD may have a more serious abnormality in Aß metabolism, possibly explaining a biological mechanism underlying the link between depression and AD.