TABLE 3.
Associations of cognitive impairment with brain volume, APOE, cognitive test scores, and neurological symptoms
| TSIMANE | MOSETEN | |||||
|---|---|---|---|---|---|---|
| Predictor | Impaired | Non‐impaired | Impaired | Non‐impaired | ||
| Mean (SD) or % | (n = 41) | (n = 407) | OR (95% CI) | (n = 18) | (n = 154) | OR (95% CI) |
| Volumes, % of intracranial volume | ||||||
| Total brain volume | 80.7 (4.9) | 84.0 (3.9) | 1.15 (1.04, 1.27) | 81.0 (3.5) | 82.7 (4.4) | 1.06 (0.94, 1.20) |
| Gray matter volume | 46.9 (5.2) | 46.6 (6.7) | 0.96 (0.90, 1.02) | 45.9 (7.5) | 46.0 (6.8) | 1.00 (0.93, 1.08) |
| White matter volume | 33.7 (7.7) | 37.4 (7.3) | 1.08 (1.02, 1.14) | 35.2 (8.4) | 36.6 (6.9) | 1.02 (0.94, 1.10) |
| APOE | ||||||
| No ε4 | 75.8% (57.7, 88.9) | 80.4% (75.7, 84.5) | Overall effect 1.65 (0.79, 3.44) | 60.0% (26.2, 87.8) | 69.9% (59.5, 79.0) | Overall effect 2.24 (0.78, 6.40) |
| One ε4 | 15.2% (5.1, 31.9) | 18.8% (14.7, 23.3) | 0 versus 1 allele 0.86 (0.30, 2.51) | 20.0% (2.5, 55.6) | 28.0% (19.1, 38.2) | 0 versus 1 allele 0.81 (0.14, 4.67) |
| Two ε4 | 9.1% (1.9, 24.3) | 0.9% (0.2, 2.6) | 0 versus 2 alleles 10.7 (1.47, 78.6) | 20.0% (2.5, 55.6) | 2.2% (0.3, 7.6) | 0 versus 2 alleles 11.5 (1.28, 102.8) |
| Cognitive test | ||||||
| Visual scan | 15.1 (6.8) | 21.7 (8.8) | 1.09 (1.03,1.16) | 16.5 (9.1) | 21.8 (12.2) | 1.04 (0.99,1.10) |
| Digit span forward | 1.5 (1.0) | 2.7 (1.0) | 1.99 (1.45,2.72) | 2.9 (1.2) | 3.6 (0.9) | 1.96 (1.11, 3.44) |
| Immediate recall | 2.9 (0.8) | 4.2 (0.9) | 6.81 (3.76,12.4) | 3.2 (0.6) | 3.9 (0.8) | 3.26 (1.50, 7.10) |
| Delayed recall | 1.4 (1.5) | 3.8 (1.9) | 1.82 (1.48,2.24) | 0.9 (1.3) | 3.0 (1.8) | 2.00 (1.41, 2.83) |
| Verbal fluency | 8.2 (2.2) | 11.6 (2.4) | 1.91 (1.55, 2.35) | 8.6 (2.5) | 10.8 (2.6) | 1.44 (1.14, 1.83) |
| Spatial span | 0.9 (1.1) | 2.6 (1.2) | 2.77 (1.98,3.86) | 2.8 (0.9) | 3.3 (1.0) | 1.57 (0.96, 2.57) |
| Stick design test | 5.1 (3.0) | 8.7 (2.6) | 1.47 (1.27, 1.70) | 8.4 (3.0) | 10.4 (1.9) | 1.63 (1.14, 2.32) |
| Neurological evaluation | ||||||
| Tremor at rest | 19.4% | 8.2% | 1.99 (0.67,5.86) | 20.0% | 2.5% | 9.16 (1.47, 57.1) |
| Bradykinesia | 71.0% | 47.0% | 1.59 (0.65,3.85) | 53.3% | 24.8% | 3.58 (1.07, 12.0) |
| Facial masking | 35.5% | 9.5% | 2.25 (0.87, 5.83) | 0.0% | 1.6% | 3.32 (0.00, 29.2) |
| Rigidity | 64.5% | 35.1% | 2.35 (1.02, 5.38) | 50.0% | 21.5% | 3.39 (1.06, 10.8) |
| Abnormal gait | 45.4% | 9.0% | 4.85 (1.80, 13.1) | 0.0% | 8.6% | 0.42 (0.00, 2.38) |
Note: Cognitively impaired includes both those diagnosed with dementia and MCI. Sample sizes: Brain volume N = 357 Tsimane; 150 Moseten. APOE N = 369 Tsimane; 103 Moseten. Visual scan N = 392 Tsimane; 152 Moseten. Digit span N = 420 Tsimane; 169 Moseten. Immediate and delayed recall and verbal fluency N = 441 Tsimane; 170 Moseten. Spatial span N = 432 Tsimane; 166 Moseten. Stick design test N = 423 Tsimane; 81 Moseten. Tremor at rest N = 349 Tsimane; 136 Moseten. Bradykinesia and facial masking N = 346 Tsimane; 136 Moseten. Rigidity N = 347 Tsimane; 135 Moseten. Abnormal gait N = 322 Tsimane; 130 Moseten. 95% CIs are shown for APOE allele frequencies based on exact binomial method. Associations with cognitive impairment were evaluated by logistic regression, adjusting for sex and age at visit. Odds ratios (ORs) are per unit of the continuous variables. Brain volume is shown as percentage of intracranial volume. APOE = apolipoprotein E. Number of APOE ε4 alleles is shown as 0, 1, or 2. Logistic regression tests the overall effect of number of ε4 alleles, and then compares one or two ε4 alleles to a reference group of no ε4 alleles. For cognitive tests, the unit of measurement is points scored on the respective test. Digits forward was administered in Tsimane for Tsimane, in Spanish for Moseten. Immediate recall is the average of three learning trials. Neurological evaluation is shown as percent manifesting each symptom. Logistic regression tests having the symptom relative to absence of the neurological symptom. OR >1.00 indicates that cognitively impaired individuals scored worse (lower brain volume, presence of ε4, lower cognitive scores, more likely to show neurological symptoms).