Background: Androgen deprivation therapy (ADT) to treat prostate cancer may be associated with an increased risk of dementia, but existing studies have shown conflicting results. Here we synthesize the literature on the association of ADT for the treatment of prostate cancer with dementia risk.

Methods: We conducted a systematic review of articles reporting the outcome of dementia among individuals with prostate cancer in those exposed to ADT versus a lesser-exposed comparison group (for example, ADT versus no-ADT; continuous versus intermittent ADT) using PubMed (1966-present), Web of Science (1945-present), Embase (1966-present) and PsycINFO (1806-present). The search was undertaken on 4 December 2016 by two authors. We meta-analyzed studies reporting an effect estimate and controlling for confounding. Random- or fixed-effects meta-analytic models were used in the presence or absence of heterogeneity per the I² statistic, respectively. Small study effects were evaluated using Egger and Begg's tests.

Results: Nine studies were included in the systematic review. Seven studies reported an adjusted effect estimate for dementia risk. A random-effects meta-analysis of studies reporting any dementia outcome, which included 50 541 individuals, showed an increased risk of dementia among ADT users (hazard ratio (HR), 1.47; 95% confidence interval (CI), 1.08-2.00; P=0.02). We separately meta-analyzed studies reporting all-cause dementia (HR, 1.46; 95% CI, 1.05-2.02; P<0.001) and Alzheimer's disease (HR, 1.25; 95% CI, 0.99-1.57; P=0.06). There was no evidence of bias from small study effects (Egger, P=0.19; Begg, P=1.00).

Conclusion: The currently available combined evidence suggests that ADT in the treatment of prostate cancer may be associated with an increased dementia risk. The potential for neurocognitive deficits secondary to ADT should be discussed with patients and evaluated prospectively.