Sample characteristics
| Covariate | Classification | Presence of serum folate deficiency | Absence of serum folate deficiency |
| n | 3418 | 23 770 | |
| N/mean (%/SD) | N/mean (%/SD) | ||
| Birth year | 1945.89 (4.3) | 1945.34 (4.2) | |
| Sex | Male | 1874 (54.8%) | 10 233 (43.1%) |
| Female | 1544 (45.2%) | 13 537 (56.9%) | |
| Smoking status | Non-smoker | 2634 (77.1%) | 20 940 (88.1%) |
| Smoker | 784 (22.9%) | 2830 (11.9%) | |
| Vitamin B12 deficiency | Absent | 15 (0.4%) | 65 (0.3%) |
| Present* | 3403 (99.6%) | 23 705 (99.7%) | |
| Folic acid supplements | Absent | 2449 (71.7%) | 20 176 (84.9%) |
| Present* | 969 (28.3%) | 3594 (15.1%) | |
| Type 2 diabetes | Absent | 2155 (63.0%) | 15 532 (65.3%) |
| Present* | 1263 (37.0%) | 8238 (34.7%) | |
| Depression | Absent | 3173 (92.8%) | 22 320 (93.9%) |
| Present* | 245 (7.2%) | 1450 (6.1%) | |
| Cognitive decline | Absent | 3050 (89.2%) | 21 243 (89.4%) |
| Present* | 368 (10.8%) | 2527 (10.6%) | |
| Outcome | All-cause mortality | 268 (7.8%) | 913 (3.8%) |
| Dementia | 115 (3.4%) | 750 (3.2%) | |
| Censored | 3035 (88.9%) | 22 107 (93.0%) |
*Presence at any time point during the follow-up.