Free Sugar Intake and Dementia Risk: A Swedish Cohort Study on Dietary Sources and Dementia Subtypes

BACKGROUND: Dementia is a growing public health concern, and although diet is a modifiable potential risk factor, the role of free sugar intake remains unclear. Excess sugar has been linked to metabolic and cardiovascular dysfunction, both associated with cognitive decline, but evidence regarding specific sugar sources is limited. OBJECTIVES: This study aimed to investigate the associations between free sugar intake, its dietary sources, and the risk of all-cause dementia, Alzheimer's disease, and vascular dementia, and to assess potential modification by apolipoprotein E (APOE) ε4 status. METHODS: We included 27,786 participants without dementia at baseline (mean age: 58 y; 61% females) from the Malmö Diet and Cancer Study, a population-based prospective cohort. Dietary intake was assessed using a validated diet history method. Dementia diagnoses were obtained from national registers and validated by memory clinic physicians. During a median follow-up of 25 y, 3224 participants (11.6%) were diagnosed with dementia. RESULTS: Free sugar intake was not significantly associated with all-cause dementia or Alzheimer's disease. However, a U-shaped association was observed for vascular dementia, with moderate intake (10%-12.5% of energy) associated with lower risk [hazard ratio (HR): 0.70; 95% confidence interval (CI): 0.52, 0.95]. Sugar-sweetened beverage intake showed no association with dementia risk. High chocolate intake was associated with lower risks of all-cause [HR for quintile 5 (Q5) compared with Q1: 0.81; 95% CI: 0.72, 0.91] and vascular dementia (HR for Q5 compared with Q1: 0.68; 95% CI: 0.50, 0.92), whereas high jam/marmalade intake was linked to a lower risk of all-cause dementia (HR: 0.86; 95% CI: 0.77, 0.97 for >10 servings per week compared with <0.5 servings per week). No significant interactions with APOE ε4 status were observed. CONCLUSIONS: Free sugar intake was not associated with overall dementia risk, but moderate intake may reduce the risk of vascular dementia. These findings suggest that future dietary guidelines for cognitive health should consider not only sugar quantity but also its food source.