The association between slow wave activity and memory improvement following cognitive-behavioral therapy for insomnia in older adults: A secondary analysis of a randomized clinical trial​.

STUDY

OBJECTIVES

This secondary analysis of a randomized clinical trial explored (1) changes in memory performance and slow-wave activity (SWA) in older adults with insomnia disorder following cognitive behavioral therapy for insomnia (CBT-I) and its component therapies, (2) associations between changes in SWA and changes in memory performance, and (3) whether individual CBT-I component therapies (behavioral therapy (BT) and cognitive therapy (CT)) differ in their associations with these outcomes.

METHODS

A secondary analysis was conducted using data from 104 older adults with insomnia disorder who underwent polysomnography and RBANS memory testing to assess immediate (list learning and story memory) and delayed memory (list recall, story recall, figure recall, and list recognition) at baseline and again at 6-months following randomization to six sessions of CBT-I, BT, or CT. Linear-mixed effects models examined changes in memory and SWA from baseline and at 6-month follow-up. Regression analyses examined relationships between changes in SWA and memory.

RESULTS

At 6-month follow-up, participants showed improvements in immediate memory (list learning and story memory) and delayed memory (list recall, story recall, and figure recall) compared to baseline. SWA did not change significantly following treatment. However, within-person increases in SWA were positively associated with improvements in list learning performance. Outcomes did not differ among treatments (CBT-I, BT, CT).

CONCLUSIONS

Although a definitive randomized controlled trial is necessary to test causality, these findings add to a growing body of literature on sleep and memory and suggest a potential role for SWA in memory processes in older adults with insomnia.

CLINICAL TRIAL: This study was a secondary analysis conducted using data from a clinical trial registered on ClinicalTrials.gov: https://clinicaltrials.gov/study/NCT02117388 . Treatments for Insomnia: Mediators, Moderators and Quality of Life.

CLINICALTRIALS: gov, NCT02117388. This secondary analysis leverages previously collected data from a clinical trial to explore changes in memory performance and SWA, and their potential associations, in older adults with insomnia disorder who received cognitive behavioral therapy for insomnia (CBT-I) or its individual component therapies cognitive therapy (CT) and behavioral therapy (BT).

STUDY IMPACT: Memory performance improved from baseline to 6-month follow-up and within-person increases in SWA were positively associated with memory performance. While this secondary analysis cannot establish causality, these findings add to a growing body of literature on sleep and memory and suggest a potential role for SWA in memory processes in older adults with insomnia. These associations provide support for further investigation in confirmatory trials designed to test causal mechanisms.