Stress and verbal memory in patients with Alzheimer's disease: different role of cortisol and anxiety.

OBJECTIVES: Chronic stress has shown to have marked effects on learning and memory. A broader understanding of these effects has special interest in the context of Alzheimer's disease (AD). This study aims to analyze the moderating effect of cognitive impairment in the relationships between stress and verbal memory performance by considering biological and psychological measures of stress.

METHOD: The sample consisted of 80 AD patients and 104 healthy controls. Salivary cortisol and state anxiety was measured as stress markers. Memory Alteration test (M@T) and Hopkins verbal learning test (HVLT-R) were used to measure verbal memory.

RESULTS: In controls, cortisol level was negatively associated with HVLT-R total, learning and delayed recall scores as well as M@T free recall scores, while in patients, such associations were not significant. In this group, cortisol negative effects were limited to HVLT-R learning and M@T semantic memory scores. In both groups, anxiety was associated with better M@T encoding and free recall scores. Besides, inverted U-shaped relationships were observed between anxiety and HVLT-R total recall and learning scores as well as M@T orientation scores.

CONCLUSION: Cortisol levels and anxiety are differentially associated with memory performance in older adults. In general, the negative relationship between cortisol levels and memory observed in healthy elderly weakens in AD. However, moderate state anxiety levels seem to be associated with a better memory performance in AD patients and in healthy elderly.