TABLE 1.
Characteristics of study participants by cognitive reserve index.
| Cognitive reserve index | ||||
|---|---|---|---|---|
| N | Low (n = 57) | High (n = 56) | p | |
| Demographics and lifestyle | ||||
| Age (years), M (SD) | 113 | 61.81 (8.03) | 62.22 (7.38) | 0.781 |
| Education (years), M (SD) | 113 | 12.71 (2.89) | 15.91 (2.88) | <.001 |
| Women | 113 | 30 (52.63) | 33 (58.93) | 0.500 |
| Current or ex‐smokers | 108 | 36 (66.67) | 31 (57.41) | 0.321 |
| Body mass index, M (SD) | 51 | 27.69 (3.82) | 27.00 (3.33) | 0.492 |
| Use of medications | ||||
| Antihypertensive | 112 | 20 (35.09) | 16 (29.09) | 0.497 |
| Lipid lowering | 112 | 7 (12.28) | 8 (14.55) | 0.725 |
| Diabetes | 112 | 8 (14.04) | 6 (10.91) | 0.617 |
| Total cardiometabolic medications, M (SD) | 112 | 0.61 (0.77) | 0.55 (0.79) | 0.643 |
| Antidepressants | 112 | 18 (31.58) | 14 (25.45) | 0.473 |
| Sleep disturbances | 112 | 10 (17.54) | 7 (12.73) | 0.478 |
| Cognition, z‐score M (SD) | ||||
| Global cognition | 91 | −0.42 (1.02) | 0.39 (0.81) | <.001 |
| Memory | 98 | −0.13 (0.95) | 0.12 (1.04) | 0.204 |
| Processing speed | 92 | −0.15 (0.92) | 0.50 (0.96) | 0.001 |
| Working memory | 78 | −0.26 (0.95) | 0.23 (1.00) | 0.030 |
| Perceptual reasoning | 93 | −0.31 (1.00) | 0.29 (0.91) | 0.003 |
| Stress measures | ||||
| Perceived Stress Scale, (_/40) M (SD) | 109 | 19.40 (6.81) | 16.07 (7.06) | 0.014 |
| Cortisol measures | ||||
| Awakening cortisol (t1), nmol/L | 102 | 9.17 (5.76) | 9.04 (6.11) | 0.910 |
| Bedtime cortisol (t6), nmol/L | 102 | 3.09 (9.12) | 2.64 (4.74) | 0.751 |
| Cortisol awakening response | 101 | 0.79 (1.33) | 0.53 (1.15) | 0.286 |
| Daily cortisol output | 101 | 87.59 (63.14) | 82.63 (77.38) | 0.725 |
| Cortisol AM/PM ratio (t1/t6) | 102 | 7.01 (5.19) | 9.91 (8.76) | 0.045 |
| AD‐related CSF biomarkers, M (SD) | ||||
| Aβ42, ng/L | 93 | 816.94 (205.64) | 809.07 (227.43) | 0.861 |
| T‐tau, ng/L | 93 | 5.63 (0.45) | 5.66 (0.48) | 0.774 |
| P‐tau181, ng/L | 93 | 3.69 (0.37) | 3.75 (0.39) | 0.488 |
Note: Values are n (column%) unless otherwise stated. Bold Italicized is p value significant at < .05. A higher score on the cognitive reserve index (CRI) is indicative of better cognitive reserve, that is, an individual has better ability to cope with AD‐related pathological changes in the brain. The CRI was categorized into low and high groups based on the median cut‐off value. The low CRI ranged between −1.68 and 0.016 (M [SD] = −0.53 [0.42]), while the high CRI ranged from 0.017 to 1.48 (M [SD] = 0.54 [0.38]). Total cardiometabolic medications include the count of the following medications: antihypertensives, lipid‐lowering, and antidiabetic agents.
Abbreviations: AD, Alzheimer's disease; CSF, cerebrospinal fluid; M, mean; SD, standard deviation.