WHO risk factor | Direction of effect on dementia from MR | ||
Protective | Null | Harmful | |
High smoking quantity | 1, 2, 3 | 4, 5, 21 | – |
Smoking initiation | 1, 5 | – | – |
Physical inactivity | 21 | 3, 5, 6, 7 | – |
Hypertension | 8, 3 | 2, 5, 9, 10, 21 | – |
Diabetes | – | 2, 3, 5, 12, 13, 14 | 11 |
High alcohol consumption | – | 2, 3, 5, 15, 16 | – |
Adiposity | – | 1, 2, 3, 5, 18, 19, 20, 21 | 17 |
Low education | – | 1, 3 | 2, 5, 21, 22, 23, 24, 25, 26, 27 |
Please note that this table does not include MR studies of dietary intake as it is too broad for inclusion.
(1) Østergaard et al 33; (2) Larsson et al 34; (3) Desai et al 30; (4) Nordestgaard et al 35; (5) Andrews et al 36; (6) Zhang et al 29; (7) Baumeister et al 37; (8) Sproviero et al 38; (9) Walker et al 39; (10) Ou et al 40; (11) Meng et al 41; (12) Thomassen et al 42; (13) Pan et al 43; (14) Walter et al 44; (15) Andrews et al 45; (16) Campbell et al 46; (17) Li et al 47; (18) Zhuang et al 48; (19) Zhou et al 49; (20) Nordestgaard et al 50; (21) Korologou-Linden et al 4; (22) Anderson et al 51; (23) Thorp et al 52; (24) Seyedsalehi et al 53; (25) Nguyen et al 54; (26) Raghavan et al 55; (27) Liu et al.56
Search strategy and selection criteria: Please note that this search was not intended to be a full systematic review of the MR literature dementia risk factors, but a comprehensive literature search to inform the table. PubMed was the only database used for the literature search. We searched for any paper that had the terms ‘Mendelian randomization’ AND ‘dementia OR Alzheimer’s disease’ AND ‘risk factor terms*’ in the title and/or abstract. We also conducted a more general search of ‘risk factors’ to identify studies that examined multiple risk factors within the same paper. Abstracts of all papers returned were read to determine suitability for inclusion in the figure. No exclusion criteria were applied and there were no date restrictions on the search. *For each risk factor, the following terms were searched: smoking—‘smoking’, ‘cigarettes’; physical inactivity—‘physical activity’, ‘physical inactivity’, ‘accelerometer’; hypertension—‘hypertension’, ‘blood pressure’, ‘antihypertensive’; diabetes—‘diabetes’, ‘glucose’; alcohol—‘alcohol’; adiposity—‘adiposity’, ‘body mass index’, ‘BMI’, ‘obesity’; low education—‘education’, ‘educational attainment’, ‘years of schooling’.