Constipation preceding stroke, dementia and Parkinson's disease in middle-aged and older adults: a population-based cohort study.

Background: Previous research indicates that constipation may be an early symptom of Parkinson's disease (PD). However, it remains uncertain whether constipation is a unique symptom prior to PD or to other major neurological disorders as well. This study aimed to explore the association between premorbid constipation and three major neurological disorders: stroke, dementia and PD.

Methods: We conducted a retrospective cohort study using data from UK Biobank. Constipation was defined based on diagnosed cases in electronic health records, self-reported instances or regular laxative use. The primary outcome was defined as the first onset of any of three neurological disorders: stroke, dementia and PD. Cox regression was used to adjust for socio-demographic characteristics, lifestyle factors, medical conditions and regular medication use.

Results: Out of 462,327 eligible participants, those with constipation were associated with higher incidence of three outcome diseases (1415/20,263 [7.0%]) than those without (18,848/442,064 [4.3%]), with adjusted hazard ratio (HR) being 1.35 [1.27-1.42]. Specifically, those with constipation had a 20%, 50% and 56% higher risk of stroke, dementia and PD, respectively. Both self-reported and diagnosed constipation were associated with a higher risk of these conditions, with HR being 1.31 (1.23-1.40) and 1.44 (1.30-1.59), respectively. Interestingly, the association between constipation and neurological disorders was stronger within the first 2 years from baseline.

Discussion: These findings support the biological link between constipation and neurological disorders. Given its potential role as a prodromal symptom for these diseases, both diagnosed and self-reported constipation should be considered in risk prediction models.