Incident herpes zoster and accelerated decline in global cognitive performance among older adults: longitudinal trajectories and psychosocial vulnerability

Long-term cognitive changes following incident herpes zoster (HZ) in older adults remain uncertain. To examine longitudinal associations of incident herpes zoster (HZ) with global cognitive performance and evaluate depressive symptoms and sleep burden in secondary analyses. This cohort included 16,324 older adults without self-reported HZ, physician-diagnosed dementia, or severe cognitive impairment at participant-specific baseline. HZ was modeled as a time-varying exposure. Mixed-effects models estimated 12-year changes in the 27-point global cognitive score. Cox models evaluated ≥ 3-point decline and incident dementia. Exploratory statistical decompositions and subgroup analyses evaluated depressive symptoms and sleep burden. Among 16,324 participants, 3,516 developed HZ. Incident HZ was associated with an annual decline in global cognitive score (β = −0.06; 95% CI [− 0.08 to − 0.05]; p < 0.001). The association persisted after excluding assessments within 2 years (β = −0.09; 95% CI [− 0.12 to − 0.07]; p < 0.001). HZ was also associated with ≥ 3-point decline (adjusted HR = 1.09; 95% CI [1.04–1.15]; p < 0.001), whereas the adjusted association with incident dementia was nonsignificant (HR = 1.12; 95% CI [0.92–1.35]; p = 0.265). Exploratory statistical decompositions yielded nonsignificant results for depressive symptoms ( p = 0.144) and sleep burden ( p = 0.515). Exploratory subgroup analyses identified interactions with baseline depressive symptoms ( p < 0.001) and sleep burden ( p = 0.041), with stronger associations at higher baseline levels. Incident HZ was associated with faster global cognitive decline among older adults. Exploratory subgroup analyses suggested stronger associations at higher baseline depressive-symptom and sleep-burden levels. No association with incident dementia was statistically significant.