Objectives: To quantitatively review the literature comparing depressed mood, anxiety and psychological distress in caregivers (CGs) of older adults with Alzheimer's disease (AD) with non-caregivers (NCGs) Methods: Eighteen independent studies comparing AD CGs (N = 2378) with NCGs (N = 70,035) were evaluated in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. Standardised mean differences (Hedges’ g) with associated 95% confidence intervals and p-values were calculated using a random-effects model. Results: Studies generally conformed to STROBE criteria in terms of their methodological and procedural detail, although data management issues that may contribute to methodological bias were identified. Pooled effect estimates revealed medium to large group differences in depression (gw = 1.01 [CI: 0.73, 1.29] p < 0.01) and anxiety (gw = 0.64 [CI: 0.39, 0.89] p < 0.01): AD caregivers reported higher symptom severity. Gender was a significant moderator: female caregivers experienced poor self-reported mood (gw = 1.58 [CI: 1.11, 2.05], p< 0.01), although this analysis was limited in power given the small number of contributing studies. Discussion: Caregivers of patients with AD experience poor mental health in comparison to the general population, with female caregivers being disproportionately affected. Further exploration of the psychosocial variables that contribute to these group differences is needed to inform effective support services and, in turn, help caregivers manage the emotional demands of AD.