A 2018 prospective cohort study using data from the National Alzheimer’s Coordinating Center followed individuals (N = 12,053) who were cognitively asymptomatic at their initial visits to determine who developed clinical signs of AD.39 Survival analysis showed several psychosocial factors—anxiety, sleep disturbances, and depressive episodes of any type (occurring within the past 2 years, clinician verified, lifetime report)—were significantly associated with an eventual AD diagnosis and increased the risk of AD.39 More research is needed to verify the impact of early intervention for these conditions on neurodegenerative disease; however, screening and treating psychosocial factors such as anxiety and depression should be maintained.
Researchers evaluated the impact of a dual sensory impairment (DSI) on dementia risk using data from 2051 participants in the Ginkgo Evaluation of Memory Study.40 Hearing and visual impairments (defined as DSI when these conditions coexist) or visual impairment alone were significantly associated with increased risk of dementia in older adults. The researchers reported that DSI was significantly associated with a higher risk of all-cause dementia (hazard ratio [HR] = 1.86; 95% CI, 1.25-2.76) and AD (HR = 2.12; 95% CI, 1.34-3.36).40 Visual impairment alone was associated with an increased risk of all-cause dementia (HR = 1.32; 95% CI, 1.02-1.71).40 These results suggest that screening of DSI or visual impairment earlier in the patient’s lifespan may identify those at high risk of dementia in older adulthood.
The American Academy of Ophthalmology recommends patients with healthy eyes be screened once during their 20s and twice in their 30s; a full examination is recommended by age 40. For patients ages ≥ 65 years, it is recommended that eye examinations occur every 1 to 2 years.43
Diet and mobility play a big role in cognition. Diet43 and exercise41,42,44 are believed to have an impact on mentation, and recent studies show memory and global cognition could be malleable later in life. A 2015 meta-analysis of 490 treatment arms of 24 randomized controlled studies showed improvement in global cognition with consumption of a Mediterranean diet plus olive oil (effect size [ES] standardized mean difference [SMD] = 0.22; 95% CI, 0.16-0.27) and tai chi exercises (ES SMD = 0.18; 95% CI, 0.06-0.29).42 The analysis also found improved memory among participants who consumed the Mediterranean diet/olive oil combination (ES SMD = 0.22; 95% CI, 0.12-0.32) and soy isoflavone supplements (ES SMD = 0.11; 95% CI, 0.04-0.17). Although the ESs are small, they are significant and offer promising evidence that individual choices related to nutrition or exercise may influence cognition and memory.
A 2018 systematic review found that all domains of cognition showed improvement with 45 to 60 minutes of moderate-to-vigorous physical exercise.44 Attention, executive function, memory, and working memory showed significant increases, whereas global cognition improvements were not statistically significant.44 A 2016 meta-analysis of 26 studies (N = 26,355) found a positive association between an objective mobility measure (gait, lower-extremity function, and balance) and cognitive function (global, executive function, memory, and processing speed) in older adults.41 These results highlight that diet, mobility, and physical exercise impact cognitive functioning.
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