Associations between different coffee types, neurodegenerative diseases, and related mortality: findings from a large prospective cohort study

Background: Observational studies have suggested associations between amount of coffee consumption and decreased risk of neurodegenerative diseases. However, these studies do not consider differences among coffee types, including sweetened, unsweetened, caffeinated, and decaffeinated varieties. Objectives: This study aims to identify associations between the consumption of various coffee types (sugar-sweetened, artificially sweetened, unsweetened, caffeinated, and decaffeinated) and risks of Alzheimer's disease and related dementias (ADRD) and Parkinson's disease (PD), along with related mortality. Methods: This prospective study included 204,847 participants (44.7% males) from the UK Biobank. Cox proportional hazards models were used to assess the associations of coffee type with neurodegenerative outcome. On the basis of coffee consumption, participants were divided into 5 groups: non- coffee consumers, > 0 - 1 cup/d, > 1 - 2 cups/d, > 2 - 3 cups/d, and > 3 cups/d. Results: Over a median follow-up of 9 y, the study documented 1696 cases of ADRD, 1093 cases of PD, and 419 neurodegenerative-related deaths. In the multivariate analysis, compared with non-coffee consumers, those with the highest intake of unsweetened and caffeinated coffee (>3 cups/d) showed hazard ratios (95% confidence intervals) of 0.75 (0.62, 0.91) for ADRD, 0.71 (0.56, 0.91) for PD, and 0.67 (0.44, 1.01) for neurodegenerative-related death. However, no significant associations were noted in either decaffeinated or sugar/artificially sweetened coffee groups (P > 0.05). Conclusions: Higher intake of caffeinated coffee, particularly the unsweetened variety, was associated with reduced risks of ADRD and PD. No such associations were observed for sugar-sweetened or artificially sweetened coffee.