Family members-mainly spouses and partners-are the primary caregivers for individuals with Alzheimer's disease and related dementias (ADRDs), chronic progressive illnesses requiring increasing levels of care. We performed a retrospective observational analysis comparing depressive symptoms of 16,650 older individuals with partners without ADRDs, and those recently (within 2 years) or less recently diagnosed (≥2 years prior), controlling for lagged sociodemographic and health characteristics. The mean number of reported depressive symptoms was 1.2 (SD = 1.8). Compared with respondents with partners with no ADRD, having a partner with any ADRD was associated with a 0.35 increase (95% confidence interval [CI] = [0.30, 0.41]), or 30% increase, in depressive symptoms. A less recent partner diagnosis was associated with a 33% increase, while a recent diagnosis was associated with a 27% increase. Clinically meaningful and longitudinally worsening depressive symptoms amplify the need to prioritize partner health and family-centered care following an ADRD diagnosis.