Blueberry Supplementation Improves Memory in Older Adults

Abstract

The prevalence of dementia is increasing with expansion of the older adult population. In the absence of effective therapy, preventive approaches are essential to address this public health problem. Blueberries contain polyphenolic compounds, most prominently anthocyanins, which have antioxidant and anti-inflammatory effects. In addition, anthocyanins have been associated with increased neuronal signaling in brain centers mediating memory function as well as improved glucose disposal, benefits that would be expected to mitigate neurodegeneration. We investigated the effects of daily consumption of wild blueberry juice in a sample of nine older adults with early memory changes. At 12 weeks, we observed improved paired associate learning (p = 0.009) and word list recall (p = 0.04). In addition, there were trends suggesting reduced depressive symptoms (p = 0.08) and lower glucose levels (p = 0.10). We also compared the memory performances of the blueberry subjects with a demographically-matched sample who consumed a berry placebo beverage in a companion trial of identical design and observed comparable results for paired associate learning. The findings of this preliminary study suggest that moderate-term blueberry supplementation can confer neurocognitive benefit and establish a basis for more comprehensive human trials to study preventive potential and neuronal mechanisms. Keywordsblueberries; memory; metabolism; Mild Cognitive Impairment; prevention; neurodegeneration Alzheimer's disease (AD) accounts for 60% to 80% of cases of dementia (1). The prevalence of AD threatens to reach epidemic proportions in the coming decades, with projections of 16 million cases in the US by 2050 (1). There are several age-related health conditions that increase vulnerability to AD, most prominently cardiovascular risks (2). However, metabolic disturbance appears to be a fundamental factor driving both cardiovascular disorders and neurodegeneration (3). The presence of insulin resistance and diabetes increase risk for AD substantially, and the risk attributable solely to hyperinsulinemia was determined to be as high as 39% in one longitudinal study (4).A number of concepts have been introduced to classify older adults at different stages of cognitive decline. Mild Cognitive Impairment (MCI) identifies individuals with increased risk for dementia and represents the first clinical appearance of neurodegeneration for a substantial subset of individuals who will progress to AD (5). There is no remedy for dementia, and it is not clear when or if effective therapy will be developed. However, it has been proposed that interventions initiated in individuals with pre-dementia conditions such as MCI might forestall progression of cognitive decline, and MCI may represent the final point at which intervention can be effective (6).Dietary approaches hold promise as effective and safe preventive interventions. Dietary factors represent the most potent determinants of metabolic health and have been shown to mitigate specific mechanisms o...

Consumption of anthocyanin-rich cherry juice for 12 weeks improves memory and cognition in older adults with mild-to-moderate dementia

“…The moderate and large effect sizes seen for the cognitive tasks highlight the clinical relevance of these cognitive improvements. These findings are consistent with those of recent human and animal studies showing improvement in cognitive performance in these domains with dietary supplementation with other anthocyanin-rich food sources (11)(12)(13)(31)(32)(33). Although, we have previously shown that intake of cherry juice does not impact acute cognition over 6h (34).…”

“…A serving size of 200ml per day was determined as being a feasible quantity that could be consumed by an older adult with mildmoderate dementia, and was chosen in the absence of empirical research that highlights a dose requirement for anthocyanin intake and cognitive outcomes. The serving size provided a more feasible serving of juice than has been used in previous similar studies, where the quantity of anthocyanin-rich beverages provided may exceed the amount that can be feasibly achieved over the long term, especially by older adults living with a neurodegenerative disease (11,13). No change to regular diet was advised.…”

“…Preliminary dietary supplementation studies have shown that blueberries (11) and concord grapes (12,13) improve aspects of memory in older adults over a 12 and 16 week intervention. Cherries, both the sweet and tart varieties, are a rich source of anthocyanins and to a lesser extent also contain flavan-3-ols and flavonols (14).…”

The potential role of fruit and vegetables in aspects of psychological well-being: a review of the literature and future directions

“…One potential reason for this is the methodological limitations of existing studies including the lack of use of a validated outcome questionnaire (97) , small sample sizes and lack of randomisation (91) . Further experimental studies have looked at the effect of FV-rich dietary patterns on psychological outcomes.…”

Polyphenols and brain health

“…Verbal learning was improved in older adults with mild cognitive impairment (MCI) after consumption of Concord grape juice (Krikorian et al, 2010a), blueberry juice (Krikorian et al, 2010b) and flavanols (Desideri et al, 2012). Although the exact mechanisms underlying these improvements are not clear, it has been suggested that polyphenols may delay the initiation of and/or slow the progression of Alzheimer's Disease (AD)-like pathology, including a potential to inhibit neuronal apoptosis triggered by neurotoxic species (e.g.…”