Blueberry Supplementation in Midlife for Dementia Risk Reduction
What this study found
Blueberry supplementation produced selective cognitive and metabolic benefits rather than broad improvements. Phonemic lexical access improved significantly, with COWA F(1,24)=10.67, p=0.003, Cohen's f=0.66, and intrusion errors on learning decreased, F(1,24)=4.69, p=0.04, Cohen's f=0.20. Memory encoding-related complaints also improved on EMQ factor 3, F(1,24)=4.93, p=0.03, Cohen's f=0.45, and fasting insulin decreased at week 12, F(1,24)=4.62, p=0.04, to 8.3 µU/mL. There were no significant effects for category fluency, verbal paired associate learning, lipids, glucose, glycated…
- Study & population
- Interventional human study in overweight, non-diabetic adults aged 50 to 65 years with subjective cognitive decline and insulin resistance, living in the Cincinnati, Ohio, USA area.
- Intervention
- Blueberry powder made from whole, freeze-dried blueberry was given orally once daily for 12 weeks at a dose equivalent to 0.5 cup of whole fruit.
- Key limitation
- The intervention was short at 12 weeks, and the available data suggest a small sample, with incomplete reporting of active-arm sample size and a mitochondrial subset analyzed in only part of the cohort.
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Open PDFOriginal abstract
Late-life dementia typically develops over a period of many years beginning in midlife. Prevalence of metabolic disturbance also accelerates in middle age and is a prominent risk factor for dementia. Preliminary studies indicate that blueberry supplementation can improve cognitive performance and influence metabolism and brain function and therefore may have a role in early intervention to prevent neurodegeneration. In a randomized controlled trial, we investigated the effects of daily blueberry supplementation in a middle-aged sample of insulin-resistant participants with elevated risk for future dementia. We enrolled overweight men and women, aged 50 to 65 years, with subjective cognitive decline (SCD) and performed pre- and post-intervention assessments of cognition and metabolism and exploratory measures of peripheral mitochondrial function. We observed improved performances for the blueberry group on measures of lexical access, p = 0.003, and memory interference, p = 0.04, and blueberry-treated participants reported reduced memory encoding difficulty in daily life activities, p = 0.03. The blueberry-treated group also exhibited correction of peripheral hyperinsulinemia, p = 0.04, and a modest trend for increased mitochondrial uncoupling, p = 0.11. The cognitive findings indicated improved executive ability in this middle-aged sample. In addition, the changes in metabolic and bioenergetic measures imply potential mechanistic factors associated with anthocyanin and proanthocyanidin actions. The demonstration of these benefits in middle-aged individuals with insulin resistance and SCD suggests that ongoing blueberry supplementation may contribute to protection against cognitive decline when implemented early in at-risk individuals.