Marital status and incident screen-positive cognitive impairment in a Taiwanese longitudinal cohort (2005–2016): Associations vary by cognitive screening instrument

Marital status has been associated with cognitive aging; however, whether such associations vary according to cognitive assessment modality remains unclear. This study examined whether associations between marital status and incident screen-positive cognitive impairment (MCI) differ by screening instrument and population subgroups in a large longitudinal cohort of community-dwelling older adults in Taiwan. We analyzed 103,863 adults aged ≥65 years from the Taipei City Elderly Health Examination Database (2005–2016). Cognitive status was assessed using the Short Portable Mental Status Questionnaire (SPMSQ; 2005–2011) and the 8-item Ascertain Dementia questionnaire (AD8; 2012–2016). Baseline marital status was categorized as married, divorced, widowed, or never married. Cox proportional hazards models with time-updated covariates were fitted separately for each assessment period, adjusting for demographic, socioeconomic, health, and lifestyle factors. Sensitivity analyses were conducted to examine potential reverse causation and variation in follow-up duration. Among 61,304 participants assessed during the SPMSQ period, never-married individuals had a higher risk of incident MCI compared with married individuals (hazard ratio [HR] 1.37, 95% confidence interval [CI] 1.08–1.74). In contrast, among 42,559 participants assessed during the AD8 period, never-married status was associated with a lower risk of MCI (HR 0.60, 95% CI 0.46–0.77). Effect modification by sex and age was observed across periods. Sensitivity analyses yielded consistent findings. Associations between marital status and incident MCI differed across assessment periods that varied in screening instrument, follow-up duration, and population composition; this measurement heterogeneity, rather than a confirmed temporal change, may account for the reversal observed among never-married participants. These findings suggest that interpretation of marital status–cognition associations should be considered alongside the measurement approach and study period under which they were derived.