Cortisol and 10-Year Cognitive Decline in Older People From the General Population.

OBJECTIVE

The present study examined bidirectional effects between salivary cortisol and cognitive functioning over time. Furthermore, the role of the APOE-ɛ4 allele as a moderator of the associations was investigated.

METHODS

Using a prospective population-based study, we analyzed data from 752 older adults followed up over 10 years. A random-intercept Cross-Lagged Panel Model was applied to each combination of one cortisol measure (at waking time, 30 min after waking, 11 am, 8 pm, cortisol awakening response, total daily output, and diurnal slope) and one cognitive measure (primary outcome: Clinical Dementia Rating Scale sum of boxes score, CDR-SB; secondary outcome: Mini-Mental State Examination) resulting in 14 (7 × 2) models.

RESULTS

Between-person effects pointed out that a higher cortisol level at 11 am was associated with increased CDR-SB scores, and a higher cortisol awakening response was associated with decreased CDR-SB scores. Within-person effects indicated that cortisol levels at 11 am and 8 pm, and total daily cortisol output were associated with subsequent lower CDR-SB scores. The APOE-ɛ4 allele did not moderate the relationship between cortisol and cognitive functioning.

CONCLUSIONS

Our findings revealed within-person associations between higher cortisol levels and better cognitive functioning at the subsequent follow-up, suggesting cortisol protective effects for cognitive decline.