Objective To determine the associations between PTSD, psychotropic medication use, and the risk for dementia.

Design Retrospective cohort.

Participants Nationwide sample of US veterans (N = 417,172) aged ≥56 years during fiscal year (FY) 2003 without a diagnosis of dementia or mild cognitive impairment at baseline (FY02‐03) and ≥1 clinical encounter every 2 years during follow‐up (FY04‐12).

Measures Demographic characteristics; diagnosis of PTSD, dementia, and medical and psychiatric comorbidity (defined by ICD‐9 codes); and psychotropic medication use including selective serotonin reuptake inhibitors (SSRI), serotonin‐norepinephrine reuptake inhibitors (SNRI), novel antidepressants (NA), benzodiazepines (BZA), and atypical antipsychotics (AA). Cox proportional hazard models examined for associations between PTSD diagnosis, psychotropic medication use, and risk for a dementia diagnosis.

Results PTSD diagnosis significantly increased the risk for dementia diagnosis (HR = 1.35; [95% CI = 1.27–1.43]). However, there were significant interactions between PTSD diagnosis and use of SSRIs (P < .001), NAs (P = .014), and AAs (P < .001) on the risk for dementia diagnosis. HR for dementia diagnosis among veterans diagnosed with PTSD and not using psychotropic medications was 1.55 [1.45–1.67]. Among veterans diagnosed with PTSD prescribed SSRI, SNRI, or AA, HR for dementia diagnosis varied by drug class use ranging from 1.99 for SSRI to 4.21 for AA, relative to veterans without a PTSD diagnosis and no psychotropic medication receipt. BZAs or SNRIs use at baseline was associated with a significantly increased risk for dementia diagnosis independent of a PTSD diagnosis.