TABLE 2.
Main characteristics of the included cohort studies.
| References | Country | Study characteristics and demographics |
Mediterranean diet score |
Cognitive outcome measure |
Results | ||||||
| Participant selection | Follow-up, y | Baseline age | Male (%) | Sample size | Diet method | MeDi score | Method | Cognitive domains | |||
| Bhushan et al. (19) | United States | US male Health professionals | 26 | 40–75 | 100 | 27,842 | FFQ | 0–9 MeDi diet score | SCF score | Global cognition | The MeDi diet was strongly related to lower subjective cognitive function |
| Charisis et al. (36) | Greece | Non-demented individuals | 3 | 64 | 40.3 | 1,046 | FFQ | 0–55 MeDi diet score | NT | Memory, language, attention, executive function, visuospatial perception | The MeDi diet was associated with a reduced risk for dementia and cognitive decline |
| Cherbuin and Anstey (13) | Australia | Healthy participants | 4 | 60–64 | 48.2 | 1,528 | FFQ | 0–9 MeDi diet score | MMSE | Global cognition | The MeDi diet was not found to be protective against cognitive decline |
| Feart et al. (15) | France | Healthy participants without dementia | 4.1 | >65 | 37.4 | 1,410 | FFQ and 24 h dietary recall | 0–9 MeDi diet score | MMSE, IST, BVRT, FCSRT | Global cognition, semantic verbal fluency, verbal production speed, immediate visual memory, verbal episodic memory | The MeDi diet was associated with lower MMSE cognitive decline |
| Galbete et al. (39) | Spain | Healthy Spanish | 8 | >55 | 71.0 | 823 | FFQ | 0–9 MeDi diet score | TICS-m | Immediate memory, delayed recall, orientation, attention, calculation, language | High adherence to the MeDi diet might be associated with better cognitive function |
| Gallucci et al. (40) | Italy | Healthy participants | 7 | >77 | 38.8 | 309 | FFQ | 0–9 MeDi diet score | MMSE | Global cognition | There was no significant association between the MeDi diet and cognitive function |
| Gardener et al. (45) | Australia | Healthy participants | 3 | >60 | 39.8 | 527 | CCVFFQ | 0–9 MeDi diet score | Global cognitive score | Verbal memory, visual memory, executive function, language, attention, visuospatial function | The AusMeDi diet was associated with better performance in the executive function cognitive domain |
| Gu et al. (18) | United States | Healthy participants without dementia | 3.8 | >65 | 33.4 | 1,219 | FFQ | 0–9 MeDi diet score | Composite cognitive Z-score | Memory, language, processing speed, visual-spatial ability | Better adherence to the MeDi diet was significantly associated with lower risk for AD |
| Haring et al. (14) | United States | Healthy participants without dementia | 9.11 | 65–79 | 0 | 6,425 | WHI-FFQ | 0–9 MeDi diet score | MMSE, CERAD, DSM-IV | Global cognition, verbal fluency, verbal learning and memory, constructive praxis, executive function | Adherence to the MeDi diet did not modify the risk for cognitive decline |
| Kesse-Guyot et al. (42) | France | Healthy participants | 13 | >45 | 53.7 | 3,083 | 24 h dietary recall | 0–9 MeDi diet score | RI-48, VFT, DST, Delis-Kaplan TMT | Episodic memory, semantic memory, short-term and working memory, mental flexibility | There was no beneficial effect of the MeDi diet adherence on cognitive function |
| Koyama et al. (46) | United States | Healthy participants | 7.9 | 70–79 | 48.7 | 2,326 | FFQ | 0–55 MeDi diet score | 3MS score | Orientation, registration, attention, recall, visuospatial ability | High adherence to the MeDi diet may reduce the rate of cognitive decline among black older adults, but not white older adults |
| Lutski et al. (41) | Israel | Cognitively normal participants | 4.8 | 45–74 | 100 | 200 | 4-day dietary record | 0–9 MeDi diet score | Computerized cognitive test | Memory, executive function, visual-spatial, attention | Poor vs high adherence was associated with a greater decline in overall cognitive performance |
| Morris et al. (17) | United States | Healthy old adults without AD | 4.5 | 58–98 | 24.0 | 923 | FFQ | 0–55 MeDi diet score | Alzheimer’s incidence rate | Episodic memory, global cognition, processing speed, reasoning, semantic memory, working memory | The MeDi diet was associated with lower AD rates |
| Olsson et al. (47) | Sweden | Healthy participants | 12 | >70 | 100 | 1,038 | 7-day dietary record | 0–9 MeDi diet score | MMSE, NINCDS-ADRDA, DSM-IV | Global cognition | Adherence to the MeDi diet did not modify the risk for cognitive decline |
| Psaltopoulou et al. (43) | Greece | Healthy participants | 8 | >60 | 35.1 | 732 | FFQ | 0–9 MeDi diet score | MMSE, GDS score | Global cognition | PUFA and seed oil as two dietary variables which were alternatively substituted for MeDi diet Score may have adverse effects on performance on cognitive function |
| Qin et al. (48) | China | Healthy participants | 5.3 | >55 | 49.7 | 1,650 | 24 h dietary recall | 0–9 MeDi diet score | Cognitive screening test | Immediate memory, orientation | There was no association among adults aged < 65 years, among adults aged > 65 years, adherence to the MeDi diet had a slower rate of cognitive decline |
| Roberts et al. (49) | United States | Healthy participants | 2.2 | 70–89 | 53.0 | 1,233 | FFQ | 0–9 MeDi diet score | CDR, NT | Memory, executive function, language, visuospatial | Adherence to the MeDi diet did not modify the risk for cognitive decline |
| Samieri et al. (50) | United States | Healthy older women | 6 | >70 | 0 | 16,058 | FFQ | 0–9 MeDi diet score | TICS, EBMT, TICS-m, category fluency test, DST | Global cognition, verbal memory, working memory, attention | Long-term MeDi diet adherence was related to moderately better cognitive change |
| Samieri et al. (51) | United States | Healthy older women | 4 | >65 | 0 | 6,174 | FFQ | 0–9 MeDi diet score | TICS, EBMT, TICS-m, category fluency test, DST | Global cognition, verbal memory | No association of the MeDi diet with cognitive decline |
| Scarmeas et al. (52) | United States | Cognitively normal participants | 4.5 | >65 | 32.0 | 1,393 | FFQ | 0–9 MeDi diet score | Alzheimer’s incidence rate, CDR | Memory, executive, language, visuospatial | Higher adherence to the MeDi diet was associated with a reduced risk of developing MCI |
| Scarmeas et al. (53) | United States | Cognitively normal participants | 4.3 | >65 | 31.0 | 1,880 | FFQ | 0–9 MeDi diet score | NAB | Memory, orientation, language, construction | Higher adherence to the MeDi diet was associated with a reduced risk of developing AD |
| Scarmeas et al. (54) | United States | Cognitively normal participants | 4 | >65 | 32.0 | 2,258 | FFQ | 0–9 MeDi diet score | NAB | Memory, orientation, language, construction | Higher adherence to the MeDi diet was associated with a reduced risk of developing AD |
| Shannon et al. (55) | United Kingdom | Healthy older individuals with CVD risk | 13 | 48–92 | 44.0 | 8,009 | FFQ | 0–15 MeDi diet score | SF-EMSE, HVLT | Global cognition, verbal episodic memory, nonverbal episodic memory, attention, simple processing speed, complex processing speed, memory | High adherence to the MeDi diet was associated with good cognitive function and low risk of poor cognition in older adults: verbal episodic memory |
| Tanaka et al. (37) | Italy | Cognitively normal participants | 10.1 | >65 | 43.5 | 832 | FFQ | 0–9 MeDi diet score | MMSE | Global cognition | Adherence to the MeDi diet can have long-lasting protective effects on cognitive decline and may be an effective strategy to prevent or delay dementia |
| Tangney et al. (56) | United States | Healthy participants | 4.1 | >65 | 26.0 | 826 | FFQ | 0–55 MeDi diet score | 19 cognitive tests | Global cognition, episodic memory, executive function, processing speed, semantic memory, working memory | The MeDi diet pattern may reduce the rate of global cognitive decline with older age |
| Tangney et al. (57) | United States | Healthy participants | 7.6 | >65 | 38.3 | 3,790 | FFQ | 0–55 MeDi diet score | EBMT, MMSE, SDMT | Global cognition | The MeDi diet pattern may reduce the rate of cognitive decline with older age |
| Trichopoulou et al. (38) | Greece | Healthy participants | 6.6 | >65 | 35.9 | 401 | FFQ | 0–9 MeDi diet score | MMSE | Global cognition | Adherence to the traditional MeDi diet was highly likely to protect against cognitive decline |
| Tsivgoulis et al. (58) | United States | Participants without MCI | 4 | 45–98 | 43.0 | 17,478 | FFQ | 0–9 MeDi diet score | SIS | Cognition | Adherence to the MeDi diet was associated with a lower likelihood of ICI in nondiabetic participants |
| Vercambre et al. (59) | United States | US female Health professionals | 5.4 | >65 | 0 | 2,504 | FFQ | 0–9 MeDi diet score | TICS, EBMT, TICS-m, EBMT | Global cognition, verbal memory, category fluency | No association of the MeDi diet with subsequent 5-year cognitive change |
| Wengreen et al. (60) | United States | Cognitively normal participants | 10.6 | >65 | 42.9 | 3,580 | FFQ | 0–9 MeDi diet score | 3MS score | Global cognition | Adherence to the MeDi diet was associated with cognitive function in older men and women |
| Wu et al. (16) | Singapore | Healthy participants | 19.7 | 45–74 | 40.8 | 16,948 | FFQ and 24 h dietary recall | 0–9 MeDi diet score | SM-MMSE | Global cognition | Adherence to the MeDi diet patterns in midlife is associated with a lower risk of cognitive impairment in later life in Chinese adults |
MeDi diet, Mediterranean diet; SCF, Subjective cognitive function; NT, neuropsychological test; MMSE, Mini-Mental State Examination; IST, Isaacs set test; BVRT, Benton visual retention test; FCSRT, Free and cued selective reminding test; TICS-m, Telephone interview of cognitive status-modified; CCVFFQ, Council of Victoria food frequency questionnaire; AusMeDi diet, Australia Mediterranean diet; WHI-FFQ, Women’s health initiative food frequency questionnaire; CERAD, Consortium to establish a registry for Alzheimer’s disease; DSM-IV, Diagnostic and statistical manual of mental disorders; RI-48, Rappel Indicé (cued recall)-48 items; TMT, trail-making test; VFT, verbal fluency tasks; DST, Digit span-backward test; 3MS score, Modified Mini-Mental State Examination score; SES, Socioeconomic status; NINCDS-ADRDA, National institute of neurological and communication disorders and stroke-Alzheimer’s disease; GDS score, Geriatric depression scale score; TICS, Telephone interview for cognitive status; EBMT, East Boston memory test; PUFA, Polyunsaturated acids; CDR, Clinical dementia rating; MCI, Mild cognitive impairment; AD, Alzheimer’s disease; NAB, Neuropsychological Assessment Battery; SF-EMSE, Short form extended mental state exam; SDMT, symbol digit modalities test; HVLT, Hopkins verbal learning test; SIS, The six-items screener; ICI, Incident cognitive impairment; SM-MMSE, Singapore modified MMSE.