Abstract
INTRODUCTION: Studies examining the risk of dementia in people with multimorbidity are commonly conducted in research cohorts or outside the UK. Multimorbidity has historically been associated with aging, but recent research suggests that more than half of incidence cases occur in adults < 50. METHODS: Using UK primary care data, adjusted Cox regressions and competing risk of death models were used to determine risk of dementia in people with multimorbidity overall and by body system. RESULTS: People with multimorbidity had a greater risk of dementia that those without multimorbidity (hazard ratio [HR] = 4.01, 95% confidence interval [CI] 3.94-4.07). Among people with multimorbidity, the risk was highest for those when a neurological condition was included (HR = 2.19, 95% CI 2.15-2.23). DISCUSSION: Managing multimorbidity, particularly neurological conditions, is key and could delay or reduce the risk of dementia. HIGHLIGHTS: People with multimorbidity experienced a greater risk of dementia than those without.Neurological multimorbidity presented the highest risk of dementia.Risk of dementia increased progressively with younger-onset multimorbidity.Preventing or managing multimorbidity effectively could reduce or delay dementia.