TABLE 5.
Human studies of nuts and cognition in elderly adults1
| Author, year (ref.) | Study design | Subjects | Duration | Results |
|---|---|---|---|---|
| O'Brien et al., 2014 (107) | Prospective cohort study: data from the Nurses’ Health Study | 15,467 female nurses aged ≥70 y (mean age 74 y) at time of cognitive testing | 21 y | Increasing nut intakes (<1/mo, 1–3/mo, 1/wk, 2–4/wk, ≥5/wk) were related to better overall cognition: verbal composite score P-trend = 0.005, global composite score P-trend = 0.003, with the difference between highest and lowest intakes equivalent to ∼2 y |
| Koyama et al., 2015 (108) | Retrospective cohort study: data from the Health Professionals Follow-Up Study | 1866 older adult men (mean age 71 y; range 63–95 y) | 8 y: nut intake noted in 2006; cognitive testing in 2014 | Higher nut consumption was significantly associated with better overall cognitive performance (>2 servings/wk, 1–2 servings/wk, 1–3 servings/mo, <1 serving/mo), P-trend = 0.02; the highest vs. lowest intakes had cognitive differences equivalent to ∼5 y |
| Nooyens et al., 2011 (109) | Prospective cohort study: data from the Doetinchem Cohort Study | 2613 men and women aged 43–70 y (mean ages by quintile of fruit and vegetable intake: 54.3–56.0 y) | 5 y (interval between cognitive tests) | Higher nut consumption was associated with better cognitive function at baseline (P-trend < 0.01); difference between highest and lowest quintiles equivalent to ∼5–8 y; no difference in cognitive change at 5 y |
| Arab et al., 2015 (110) | Cross-sectional study; 24-h recall data compared 3 groups:• Walnuts alone• Walnuts with other nuts• No nuts | NHANES1988–1994: age 20–59 y, n = 5662; age ≥60 y, n = 50541999–2002: age ≥60 y, n = 2975 | Not applicable | Positive associations were seen between walnut consumption and cognitive function among all age groups (P < 0.01) |
| Katsiardanis et al., 2013 (111) | Cross-sectional study: population based in Velestino, Greece | 557 elderly adults ≥65 y; 50% of men and 67% of women had MCI by MMSE | Not applicable | Intake of pulses, nuts, and seeds (assessed as a group) was associated with a lower likelihood of MCI (MMSE <24) in men only (P = 0.04); no food groups were associated with MCI in women |
| Cardoso et al., 2016 (112) | RCT: 1 brazil nut (mean 5 g, ∼288.75 μg selenium) daily vs. control | 31 older adults with MCI (20 completing) (mean age 77 ± 5.3 y) | 6 mo | Overall neuropsychological battery score assessing global cognition did not differ (P = 0.138); however, significant improvements in verbal fluency (P = 0.007) and constructional praxis (P = 0.031) subtests were seen with the intervention |
1
MCI, mild cognitive impairment; MMSE, Mini-Mental State Examination; RCT, randomized clinical trial; ref., reference.