Serum levels and mutual correlations of amyloid ß in patients with depression.

AIM: Epidemiological studies have shown that depression is a risk factor for Alzheimer's disease (AD). Although the biological mechanism underlying the link between depression and AD is unclear, altered amyloid ß (Aß) metabolism in patients with depression has been suggested as a potential mechanism. Results from previous studies of Aß metabolism in patients with depression have been inconsistent, and Aß polymerization, which is a crucial process in AD pathology, has not previously been assessed. METHODS: Serum levels of Aß40, Aß42 and Aß oligomers were evaluated in 104 inpatients with major depressive disorder (MDD) and 132 healthy control individuals. RESULTS: Lower serum Aß42 levels were observed in patients with MDD, but there was no difference in serum Aß oligomer levels between the MDD group and the healthy control group, even in older adults. Interestingly, serum Aß oligomer levels in patients with MDD were dependent on serum Aß42 levels, regardless of age, and this relationship was not observed in the control group. CONCLUSIONS: These results suggest that Aß42 is more prone to aggregation and polymerization in patients with depression than in healthy individuals, suggesting a possible mechanism underlying the transition from depression to AD. Geriatr Gerontol Int 2020; 20: 125-129.

Serum levels of TDP-43 in late-life patients with depressive episode.

BACKGROUND: Recent reports have suggested a relationship between affective disorder including depression and bipolar disorder (BP) and frontotemporal dementia (FTD). TAR DNA binding protein (TDP) -43 is a protein found in the brain and peripheral fluid of patients with FTD. To examine a possible association between affective disorders and FTD, serum levels of TDP-43 were evaluated in late-life patients with major depressive episode (MDE). METHODS: The subjects were 74 late-life (≥50 years old) inpatients with DSM-IV or -5 MDE (58 had major depressive disorders and 16 had BP) and 58 healthy subjects. Patients were recruited from Juntendo Koshigaya Hospital, Saitama, Japan, between January 2005 and May 2017. Serum TDP-43 levels were measured using an ELISA kit. RESULTS: Serum levels of TDP-43 were significantly higher in the MDE group than the control group independent of age and sex. LIMITATIONS: All patients were on antidepressant medication. CONCLUSIONS: Our finding suggests that some depressive patients may be in a prodromal stage of FTD or very-early stage of FTD comorbid with depression.

Increased Serum Levels of α-Synuclein in Patients With Major Depressive Disorder.

OBJECTIVE: Epidemiologic studies have demonstrated that depression is a risk factor for dementia. In particular, dementia with Lewy bodies (DLB) has been noted to be highly relevant to depression. It has been suggested that α-synuclein (α-syn), a major component of Lewy bodies, is related to the onset and progression of DLB. To investigate the relationship between depression and DLB, we compared serum α-syn levels of patients with depression to those of healthy subjects. METHODS: The subjects were 103 inpatients with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), or DSM-5 major depressive disorder (MDD) and 132 healthy comparisons. Patients were recruited from Juntendo Koshigaya Hospital, Saitama, Japan, between June 2010 and November 2016. Serum α-syn levels were measured using an enzyme-linked immunosorbent assay kit. Serum α-syn levels were compared using a 2 (age group [<60 years versus ≥60 years]) × 2 (diagnosis [MDD versus comparison]) analysis of variance. RESULTS: There was no significant main effect of age (F = 1.167, df = 1, 231, p = 0.281). There was a significant main effect of diagnosis (F = 44.657, df = 1, 231, p <0.001), with higher α-syn levels in the MDD group versus the healthy comparison group, regardless of age. CONCLUSION: The present results suggest that depression may affect the metabolism of α-syn; there is a possibility that depression is not only a prodromal symptom of DLB but also a causal risk factor for DLB.