Table 3.
Summary of observational studies assessing milk intake and cognitive function.
| Participants | Numbers | Design | Diet measures | Cognitive tests | Outcome | Results | References |
|---|---|---|---|---|---|---|---|
| 60+ years at end of study; living in Japan | 1,774 (475 men, 1,299 women) | Prospective study; diet was assessed during mid-life and then cognition was measured 25–30 years later | Food consumption frequencies | CASI for all; Informative Questionnaire on Cognitive Decline in the Elderly, Hachinski's Ischemic Score and Clinical Dementia Rating for a subset of participants | Positive | Daily milk intake reduced likelihood of vascular dementia compared to milk consumption less than twice a week (OR = 0.26, P = 0.002) | Yamada et al. (29) |
| 80+ years at end of study; living in Australia | 857 men | Prospective study; diet was assessed and then cognition was measured 5 years later | Diet questionnaire | MMSE | Negative | Regular consumption of milk reduced likelihood of MMSE score ≥25 (OR = 0.69, P < 0.05) | Almeida et al. (30) |
| Elderly (age not defined); from the US | 1,056 (345 men, 711 women) | Cross-sectional study; single in-person session with each participant | 10-item FFQ | Mental status questionnaire | No association between milk intake and cognitive scores (P = 0.18 for AOR) | Rahman et al. (31) | |
| 50–82 at end of study; living in China | 2,062 (1,051 men, 1,011 women) | Retrospective study | Childhood data extracted from medical records | Battery including Flud object memory evaluation, Fuld verbal fluency, WISC-R, WAIS-R digit span | Positive | Daily milk intake during childhood reduced risk of low combined cognitive score in later life (AOR = 0.64, P < 0.001) | Zhang et al. (32) |
| 60+ years; living in the US | 6,471 | Cross-sectional study; single in-person session with each participant (from survey records) | 24 h dietary recall | Story recall test (4,282), digit-symbol substitution test (2,189) | No association | No differences in cognitive test scores between milk intake groups (P > 0.05) | Park and Fulgoni (17) |
| 70+ years in at end of study; living in the US | 5,987 | Prospective study; diet was assessed twice and cognition was measured three times over 25 years | FFQ | Decall Word Recall Test, Digit Symbol Substitution Test, Word Fluency Test | Negative | Daily milk intake associated with lower global cognition scores compared to almost never consumption (z score = −1.04 vs. −0.94) | Petruski-Ivleva et al. (33) |
| 50+ years; living in South Korea | 276 (105 men, 171 women) | Cross-sectional study; single in-person session with each participant | 112-item FFQ | MMSE | Positive | Increased milk consumption reduced odds of MCI (AOR = 0.421, P = 0.044) | Kim and Yun (21) |
| 60+ years; living in the Netherlands | 619 (369 men, 350 women) | Cross-sectional study; single in-person session with each participant (baseline data for longitudinal study) | 190-item FFQ | MMSE, Digit Span forward and backward, Trail Making Test, Stroop Color-Word Test, Letter Fluency, Symbol Digit Modalities Test, Rey Auditory Verbal Learning Test | No association | No association between total milk consumption and any of the cognitive domains tested (P > 0.05 for β and AOR) | de Goeij et al. (22) |
| 65+ years; living in Canada | 7,945 (4,079 men, 3,866 women) | Cross-sectional study; single in-person session with each participant (baseline data for longitudinal study) | 36-item short diet questionnaire | 15-word Rey Auditory Verbal Learning Test immediate and delayed recall, Mental Alternation Test, high interference of the Victoria Stroop test (interference/dot), event- and time-based prospective memory tests, and 2 verbal fluency tests, Animal Fluency Test and Controlled Oral Word Association Test of the letters, choice reaction time | No association | No association between milk intake and cognitive test scores (P > 0.05 for partial η2) | Tessier et al. (27) |
| 42+ years at start of study; living in Finland | 1,741 men | Prospective study; diet was assessed and then cognition was measured 4 years later | 4-day food recording | Dementia diagnosis (1,259 participants); MMSE, trail making test A, verbal fluency test, selective reminding test, Russell's adaptation of the visual reproduction test (482 participants 60+ years) | Negative/No association | No association between milk intake and dementia or AD risk (P = 0.18 and 0.20) High milk intake group had lower verbal fluency test scores than low milk intake group (30.6 vs. 33.5, P = 0.03) |
Ylilauri et al. (28) |
AOR, Adjusted odds ratio; CASI, Cognitive Ability Screening Instrument (contains items similar to MMSE and Hasegawa's Dementia Scale); FFQ, Food frequency questionnaire; MMSE, Mini-Mental State Exam; WISC-R, Wechsler Intelligence Scale for Children-Revised; WAIS-R, Wechsler Adult Intelligence Scale-Revised.