Cognitive impairment definitions* | Individual cognitive domains† | ||||||||||
2 domains 1.5 SD below | 1 domain 2 SD below | 2 domains 2 SD below | All three definitions pooled | Visual memory | Verbal memory | Verbal fluency | Working memory | Processing speed | Complex attention | Psychomotor speed | |
OR (CIs) using logistic regression | Coefficient (CIs) using linear regression | ||||||||||
Age | 1.08** (1.02 to 1.13) | 1.07* (1.02 to 1.12) | 1.10* (1.02 to 1.17) | 1.05* (1.02 to 1.09) | −0.04** (−0.06 to –0.02) | −0.02* (−0.03 to –0.01) | 0.004 | −0.01 | −0.02** (−0.03 to −0.01) | −0.03** (−0.05 to –0.02) | −0.03** (−0.05 to –0.02) |
MoCA score | 0.44** (0.31 to 0.63) | 0.49** (0.36 to 0.67) | 0.49** (0.35 to 0.69) | 0.49** (0.38 to 0.63) | 0.26** (0.17 to 0.36) | 0.16** (0.09 to 0.22) | 0.24** (0.17 to 0.30) | 0.14** (0.08 to 0.20) | 0.12** (0.06 to 0.18) | 0.28** (0.20 to 0.36) | 0.07 |
Multivariate analysis adjusted for age. Premorbid IQ was highly collinear with MoCA score and was therefore not included in the multivariate model.
*P<0.05; **p<0.005.
*Impairment defined by number of cognitive domains either 1.5 or 2 SD below healthy control group mean, all three definitions pooled into fourth cognitive impairment category.
†Specific cognitive tests used for each domain are as follows: visual memory (Rey-Osterrieth Complex Figure Test recall score), verbal memory (California Verbal Learning Test trials 1–5), verbal fluency (Controlled Oral Word Association Test FAS sum), working memory (Letter Number Sequencing score), processing speed (Coding Score), complex attention (Trail Making Test B time inverse), psychomotor speed (Finger Tap Test dominant hand score). Test scores were expressed as z-scores in comparison with healthy control group data.