Curcumin, which is derived from the curry spice turmeric, is a polyphenol with anti-inflammatory, antioxidant, and anti-amyloid properties that may have a promising role in preventing AD in cognitively intact individuals. Initial trials with curcumin have yielded mixed results on cognition, which was partly related to the low solubility and bioavailability of its formulation.52 However, a recent 18-month double-blind randomized placebo-controlled trial found positive effects on memory and attention, as well as reduction of amyloid plaques and tau tangles deposition in the brain, in non-demented older adults age 51 to 84 who took Theracumin, a highly absorptive oral form of curcumin dispersed with colloidal nanoparticles.53 A longer follow-up is required to determine if curcumin can delay or prevent AD.
The role of alcohol in AD prevention is controversial. Overall, data from prospective studies has shown that low to moderate alcohol consumption may be associated with a reduced risk of AD (level III).54 Alcohol drinking in mid-life showed a U-shaped relationship with cognitive impairment; both abstainers and heavy drinkers had an increased risk of cognitive decline compared with light to moderate drinkers (level III).55 Binge drinking significantly increased the odds of cognitive decline, even after controlling for total alcohol consumption per week.55
The definition of low-to-moderate drinking varies substantially among countries. In addition, the size and amount of alcohol contained in a standard drink may differ.56 According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA),57 moderate drinking is defined as up to 1 drink daily for women and 2 drinks daily for men. Binge drinking involves drinking >4 drinks for women and >5 drinks for men, in approximately 2 hours, at least monthly. In the United States, one standard drink contains 14 grams of pure alcohol, which is usually found in 12 ounces of regular beer, 5 ounces of wine, and 1.5 ounces of distilled spirits (vodka or whiskey).58
In a 5-year prospective Canadian study, having 1 drink weekly (especially wine) was associated with an up to 50% reduced risk of AD (level III).59 In the French cohort PAQUID, mild drinkers (<1 to 2 drinks/day) and moderate drinkers (3 to 4 drinks daily) had a reduced incidence of AD compared with non-drinkers. Wine was the most frequently consumed beverage in this study.60 Other studies have found cognitive benefits from mild to moderate drinking regardless of beverage type.54 However, a recent study that included a 30-year follow-up failed to find a significant protective effect of light drinking over abstinence in terms of hippocampal atrophy.61 Atrophy of the hippocampus was correlated with increasing alcohol amounts in a dose-dependent manner, starting at 7 to 14 drinks/week (level III).61
Research has shown that moderate and heavy alcohol use or misuse can directly induce microglial activation and inflammatory mediators’ release, which induce amyloid beta pathology and leads to brain atrophy.62 Hence, non-drinkers should not be advised to begin drinking, because of the lack of RCTs and the concern that beginning to drink may lead to heavy drinking. All drinkers should be advised to adhere to the NIAAA recommendations.13
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