Although studies of caffeinated coffee have been heterogeneous and yielded mixed results (beneficial effect vs no effect on delaying cognitive decline), systematic reviews and meta-analyses of cross-sectional, case-control, and longitudinal cohort studies have found a general trend towards a favorable preventive role (level III).63-65 Caffeine exhibits its neuroprotective effect by increasing brain serotonin and acetylcholine, and by stabilizing blood-brain-barrier integrity.66 Moreover, in an animal study, mice given caffeine in their drinking water from young adulthood into older age had lower amyloid beta plasma levels compared with those given decaffeinated water.67 These findings suggest that in humans, 5 cups of regular caffeinated coffee daily, equivalent to 500 mg of caffeine, could be protective against cognitive impairment. Other caffeinated beverages, such as tea or soft drinks, contain up to 4 times less caffeine per serving; many more servings would therefore be required to reach the target amount of 500 mg/d of caffeine.67 Data from the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study demonstrate a 65% reduced risk of dementia/AD in individuals who consumed 3 to 5 cups of regular coffee daily in mid-life.68
An Italian study showed that older adults who don’t or rarely drink coffee (<1 cup daily) and those who recently increased their consumption pattern to >1 cup daily had a higher incidence of MCI than those who habitually consumed 1 to 2 cups daily.69 Therefore, it is not recommended to advise a change in coffee drinking pattern in old age. Older adults who are coffee drinkers should, however, be educated about the association between heavier caffeine intake and anxiety, insomnia, and cardiac arrhythmias.70
Despite its more modest caffeine levels, green tea is rich in polyphenols, which belong to the family of catechins and are characterized by antioxidant and anti-inflammatory properties.71 In a Japanese cohort, higher green tea consumption (up to 1 cup daily) was associated with a decreased incidence of MCI in older adults.72 More studies are needed to confirm its potential preventative role in AD.
Which lifestyle change is the most important?
Focusing on a single lifestyle change may be insufficient, especially because the bulk of evidence for individual interventions comes from population-based cohort studies (level III), rather than strong RCTs with a long follow-up. There is increasing evidence that combining multiple lifestyle modifications may yield better outcomes in maintaining or improving cognition.73
The Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), a large, 2-year RCT that included community-dwelling older adults (age 60 to 77) with no diagnosis of major neurocognitive disorder, found that compared with regular health advice, multi-domain interventions reduced cognitive decline and improved overall cognition, executive functioning, and processing speed. The interventions evaluated in this study combined the following 4 modalities74:
- a healthy diet according to the Finnish nutrition recommendations (eating vegetables, fruits, and berries [minimum: 500 g/d], whole grain cereals [several times a day], and fish [2 to 3 times/week]; using low-salt products; consuming fat-free or low-fat milk products; and limiting red meat consumption to <500 g/week
- regular physical exercise tailored for improving muscle strength (1 to 3 times/week) coupled with aerobic exercise (2 to 5 times/week)
- cognitive training, including group sessions that have a social activity component and computer-based individual sessions 3 times/week that target episodic and working memory and executive functioning
- optimal management of cardiovascular risk factors.
Continue to: This multi-domain approach...