TABLE 3.
Characteristics of the studies evaluating the association between dairy intake and cognitive performance1
| Exposure | Outcome definition: cognitive performance | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Authors (ref), country | Study design | Participants (n) | Age (y) | Follow-up (y) | Male (%) | Baseline age (y) | Method of assessment | Category | Type | Method of assessment | Association measure | Controlled variables |
| Vercambre et al. (27), France | Cohort | 4809 women from the Aging subcohort of the Etude Epidémiologique de Femmes de la Mutuelle Générale de l'Education Nationale | 65.5 ± 1.8 | 13 | 0 | 45–64, 65–79, >80 | Self-administered questionnaires at baseline only. Use of photographs to facilitate estimation of portion size. | Ts of food intake | Cognitive decline | DECO scale,2 range: 0–38 (cutoff 33, sensitivity 89%, specificity 67%). | Milk and yogurt: 234.8 ± 191.9, P for trend 0.182. T2 vs. 1: OR: 1.21* (0.97, 1.50); T3 vs. 1 OR: 1.17* (0.93, 1.46). Dairy desserts:3 22.89 ± 35.78, P- trend 0.010.* Group 2 vs. 1: OR: 1.02* (0.82, 1.28); Group 3 vs. 1: OR: 1.33* (1.07, 1.65). | Age, education, physical activity, hypertension, diabetes mellitus, BMI; smoking habits, energy intake, supplement consumption, postmenopausal hormones use, hypercholesterolemia, coronary heart disease, stroke, cancer, depression. |
| Ozawa et al. (28), Japan | Prospective cohort, community-based | 1081 subjects from the Hisayama study | Q1: 68.6 ± 6.4, Q2: 69.8 ± 6.4, Q3: 68.9 ± 6.1, Q4: 70.4 ± 6.8 | 17 | 42.2 | 60 | 70 semiquantitative FFQ items only at baseline. 1-d average intake of dairy products: 84.6 g. | Qs (g/d): women: <45, 45–96, 97–197, ≥198; men: <20, 20–75, 76–173, ≥174 | Dementia (Alzheimer or vascular dementia) | DSM-III-R to define the diagnosis of dementia. Criteria NINCDS-ADRDA to define subjects with Alzheimer disease. NINDS to determine vascular dementia. Autopsy (74.7%). | All-cause dementia: HR (95% CI), (P-trend 0.09). Q2: 0.85 (0.62, 1.18); Q3: 0.69 (0.50, 0.96); Q4: 0.80 (0.57, 1.11). Alzheimer disease: HR(95% CI), (P-trend 0.03). *Q2: 0.64 (0.41, 0.99); Q3: 0.57 (0.37, 0.87); Q4: 0.63 (0.41, 0.98). Vascular dementia: HR (95% CI), (P-trend 0.14). Q2: 1.02 (0.59, 1.77); Q3: 0.74 (0.42, 1.33); Q4: 0.69 (0.37, 1.29). | Age; sex; education; physical activity; stroke; hypertension; diabetes mellitus; total cholesterol; BMI; smoking habits; energy intake; vegetable, fruit, fish, and meat intake; alcohol consumption. |
| Kesse-Guyot et al. (29), France | Cohort | 3076 subjects from the SU.VI.MAX 2 study after excluding participants aged <45 y at baseline and those with missing data | Age of participants at cognitive evaluation: 65.5 ± 4.6 | 13 | T1: 59.9, T2: 52.1, T3: 55.6 | 52 (range: 45–65) | Computerized 24-h dietary records bimonthly. Self-reporting with validated photographs to assess portion size. Food composition table. | Ts: (g/d): T1: <191.6; T2: 191.6–327.2; T3 >327.2. Mean ± SD consumption (g/d): men: 280.7 ± 165.4; women: 277.2 ± 160.6 | Cognitive functioning. Clinical examination, neuropsychological evaluation by trained neuropsychologists | Episodic memory.4 Lexical-semantic memory.5 Working memory.6 Mental flexibility.7 Verbal memory. | Total dairy product (adjusted mean differences): Medium-T2: 0.05 (−0.78, 0.89); High-T3: −0.29 (−1.15, 0.57). Milk: Medium-T2: −0.09 (−0.94, 0.76)*; High-T3: −0.99 (−1.83, −0.15).* Cream: Medium-T2: 0.85 (−0.01, 1.70); High-T3: 0.47 (−0.37, 1.31). Yogurt: Medium-T2: 0.46 (−0.38, 1.31)*; High-T3: 0.64 (−0.30, 1.57).* Cheese: Medium-T2: 0.65 (−0.19, 1.49); High-T3: 0.63 (−0.21, 1.47). | Age, gender, education, physical activity, stroke, hypertension, diabetes mellitus, BMI, energy intake, occupation, alcohol intake, depression, self-rated health, adherence to the Mediterranean diet, Western and healthy pattern score. |
| Petruski-Ivleva et al. (30), United States | Cohort | 13,752 subjects from theARIC cohort | Not included in the article | 20 | 44 | 45–64 | FFQ on 2 occasions during the follow-up period | Milk intake: almost never (11%); <1 glass8/d (50%); 1 glass/d (15%); >1 glass/d (24%). Serving of dairy.9 | Cognitive functioning | Verbal learning10 (DWRT). Executive function11 (DSST). Expressive language12 (WFT). All test scores were converted to z scores. | Global results (20-y decline)-adjusted mean differences-: Almost never: −0.94 (−1.00, −0.88); <1 glass/d (5%): −0.99 (−1.01, −0.96); 1 glass/d (6%): −1.00 (−1.05, −0.95); >1 glass/d (11%): −1.04 (−1.08, −1.01). | Age; gender; education; physical activity; hypertension; diabetes mellitus; BMI; smoking habits; energy intake; vegetable, fruit, and alcohol intake; CHD; cancer; adherence to the Mediterranean diet. |
1Values are means ± SDs or measures (95% CIs) unless otherwise indicated. *Significant association. ARIC, Atherosclerosis Risk in Communities; CHD, coronary heart disease; DECO, Detérioration Cognitive Observée (observed cognitive deterioration); DSM-III-R, Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition; DSST, Digit Symbol Substitution Test; DWRT, Delayed Word Recall Test; NINCDS-ADRDA, National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association; NINDS, National Institute of Neurological Disorders and Stroke; Q, quartile; ref, reference; SU.VI.MAX, SUpplémentation en Vitamines et Minéraux AntioXydants; T, tertile; WFT, Word Fluency Test.
2The DECO scale is a 19-item Likert scale that allows the evaluation of recent cognitive decline based on alterations of the capacity to perform specific tasks related to memory, attention, visuospatial, and language skills. A DECO score <33 constituted a group of recent cognitive decliners.
3Group 1, group 2, and group 3 were defined as no consumption, consumption less than or equal to the median, and consumption above the median for dairy desserts and ice cream, respectively.
4Episodic memory was evaluated with the RI-48 test (delayed cued recall test comprising a list of 48 words).
5Lexical-semantic memory was assessed by 2 verbal fluency tasks (semantic fluency and verbal fluency).
6Working memory was assessed with the forward and backward digit span tests.
7The Delis-Kaplan trail-making test was used to assess mental flexibility.
8236.5-mL glass.
9Intake of all dairy (including skim or low-fat and whole milk, yogurt, ice cream, cottage cheese, other cheese, and butter) in servings per day. One serving of dairy was equal to an 8-ounce (236.5 mL) cup of milk, 1 cup of yogurt, half a cup of ice cream, half a cup of cottage cheese, 1 slice of hard cheese, or 1 pat of butter.
10Verbal learning and short-term memory were assessed via the DWRT.
11Executive function was assessed via the DSST.
12Expressive language was assessed via the WFT.