Soluble amyloid-β levels and late-life depression

Area of Science:

• Neuroscience
• Gerontology
• Psychiatry

Background:

• Late-life major depression (LLMD) is a heterogeneous disorder linked to medical comorbidities, vascular factors, and Alzheimer's disease (AD).
• The association between LLMD and AD is debated, with LLMD potentially being a risk factor or an early symptom of dementia.
• Amyloid-beta 42 (Aβ42) is crucial in AD pathogenesis, prompting investigation into its relationship with LLMD.

Purpose of the Study:

• To review studies examining the relationship between soluble Aβ42 levels and LLMD.
• To understand how Aβ42 dynamics might be associated with LLMD and its potential role in the LLMD-AD continuum.

Main Methods:

• Systematic review of 15 studies analyzing soluble Aβ42 levels (plasma and/or cerebrospinal fluid) in relation to LLMD.
• Analysis of potential confounding factors influencing the observed relationships.

Main Results:

• The relationship between soluble Aβ42 levels and LLMD was equivocal across studies.
• Some studies reported elevated Aβ42 in LLMD, while others found decreased levels.
• Inconsistent findings may stem from diagnostic unreliability, varied assessment criteria, or distinct LLMD subtypes.

Conclusions:

• The current evidence does not establish a clear link between soluble Aβ42 levels and LLMD.
• Heterogeneity in LLMD diagnosis and potential disease-stage specificities in Aβ42 trajectories may explain the inconsistent results.
• Further research is needed to clarify the complex interplay between LLMD, Aβ42, and dementia risk.