Alzheimer’s disease (AD) is the most frequent cause of dementia, linked to morbidity
and mortality among elderly patients. Recently, several clinical studies suggested that depression
is a potential risk factor for cognitive decline and AD. A review of meta-analyses was performed,
calculating pooled odds ratios to estimate the risk of AD in people with a prior diagnosis (or clinically
significant symptoms) of depression. A total of six meta-analyses which represented 28 individual
studies were analyzed. A significant association between depression and AD was found (OR = 1.54,
95% CI [1.02–2.31]; p = 0.038). The results showed that heterogeneity across studies was substantial.
We found a significant positive effect size for clinical measures of depression, but not for symptomatic
rating scales, in the association of depression with risk of AD. The type of rating scale used to assess
depression and the cut-off criteria selected also moderated the relationship between depression and
AD risk. We found that studies that used clinically significant criteria for diagnosis of depression had
more consistent and significant results than studies that used symptomatic scales.
