TABLE 1.
Nut consumption and cognitive performance in young and middle-aged adults (aged ≤60 y)
| Author, year, country | Study design | Study population | Nut intake (type, amount) | Comparison group | Cognitive measure | Findings |
|---|---|---|---|---|---|---|
| Arab & Ang, 2015, USA (22) | Cross-sectional | n = 5356 free-living (20–59 y) | Walnut (WWHC, WWON) | Nonconsumers | Simple reaction time test | WWHC: mean difference: –17.4 ms (β: –16.4; 95% CI: –21.4, –14.5; P = 0.031)WWON: mean difference: –10.5 ms (β: –10.5; 95% CI: –13.7, –9.3; P = 0.021) |
| Symbol digit substitution test | WWHC: mean difference: –0.35 s (β: –0.39; 95% CI: –0.71, –0.24; P = 0.011)WWON: mean difference: –0.31 s (β: –0.30; 95% CI: –0.70, –0.31; P = 0.011) | |||||
| Single digit learning test | WWHC: mean difference: –1.42 s (β: –2.38; 95% CI: –15.11, –0.39; P = 0.051)WWON: mean difference: –1.31 s (β: –2.21; 95% CI: –14.47, –0.51; P = 0.0011) | |||||
| Dhillon et al., 2017, USA (37) | RCT, parallel-arm (12 wk) | n = 86 overweight (18–60 y) | Almond, 15% daily energy (energy-restricted diet) | Nut-free diet (energy-restricted diet) | Immediate memoryImmediate attention | No differences between groupsNo differences between groups |
| Attention (delayed) | No differences between groups | |||||
| Delayed memory | No differences between groups | |||||
| Verbal list recognition test | No differences between groups | |||||
| Pribis et al., 2012, USA (42) | RCT, crossover (8 wk) | n = 47 college students (18–25 y) | Walnut within banana bread, 60 g/d | Placebo | Raven's Advanced Progressive Matrices | No differences between groups |
| Watson-Glaser Critical Thinking Appraisal | Difference: 11.2%; 95% CI: 2.9, 19.6; EF: 0.567; P = 0.009 | |||||
| Wechsler Memory Scale – Third Edition | No differences between groups |
1
Adjusted for age, gender, race, education, BMI, smoking, alcohol consumption, and physical activity. EF, Cohen's d effect size; RCT, randomized control trial; WWHC, walnuts with high certainty; WWON, walnuts with other nuts.