1. Sleep Disturbance as a Risk Factor for
Memory Deficits in Late Life Depression
Poster Number: NR7-65
Derek Pisner, B.A., Alana Kivowitz, B.A., David Bickford, B.A., Katie Tegenkamp, B.S., Ross Crothers, B.A.,
J. Craig Nelson M.D., & R. Scott Mackin PhD
Late Life Depression Program
We gratefully acknowledge grant support for this study: NIMH K08 MH , UCSF Leon Epstein Fund
RESULTS:
Participants included 70 individuals from an ongoing study of LLD. 21 participants were classified as having sleep disturbance, and 49 were classified as having no sleep disturbance. The groups did not differ with respect to age, education, and gender (Table 1).
The “Sleep disturbance” group demonstrated significantly poorer performance than the “No sleep disturbance” group in delayed verbal memory HVLT Delayed Recall, F(3,70) = 6.7, p = 0.008, and WMS Delayed Recall, F(3,70) = 5.5, p = Delayed visual memory performance did not differ significantly between groups: BVMT F(3,70) = 1.2, p = 0.28 (Figure 1).
On measures of verbal learning, there were no significant differences between groups: HVLT Learning (Uncorrected Model) F(3,70) = 1.4, p = 0.24; WMS Immediate Recall (Corrected Model) F(3,70)=2.0, p=0.12; BVMT Learning Recall F(3,70)=.86, p=.47 (Figure 2).
Finally, convergent validity of the HDRS insomnia composite score was moderate (r = 0.4, p < 0.001), suggesting that the sleep disturbance measure designed in the present study is consistent with other subjective measures.
OBJECTIVE:
The purpose of this study is to evaluate the association of sleep disturbance with learning and memory in elderly individuals with Late Life Major Depression (LLD) using a convenient screening tool. We hypothesize that participants with severe sleep disturbance will exhibit deficits in learning and memory.
BACKGROUND:
Previous research has established associations between sleep disturbance in LLD and cognitive performance, particularly in the domain of memory. Despite such findings, research has yet to: 1) delineate what specific aspects of memory are associated with sleep disturbance in LLD; 2) replicate findings from prior studies whose participant pools were limited to non-depressed and/or mildly depressed senior individuals. In addressing the latter research need, the present study includes a sample of individuals suffering from moderate-severe late life major depression. Moreover, prior studies have shown that depressed older adults can reasonably estimate their total sleep and sleep onset latency (Naismith et al 2009). Accordingly, the present study uses a clinician rating of the patients report of sleep disturbance-- the insomnia subscale on the Hamilton Depression Rating Scale (HDRS)-- to test associations between sleep disturbance, learning, and memory in LLD.
METHODS:
Eligibility Criteria: Older adults (> 65 years of age) with a SCID diagnosis of Major Depressive Disorder (MDD), a Hamilton Depression Rating Scale (HDRS) score of at least 19, and no evidence of dementia (MMSE > 24).
Depression was evaluated by licensed psychologists using the Structured Clinical Interview for the Diagnoses of DSM-IV Disorders (SCID) and criteria from the Diagnostic and Statistical Manual, 4th edition (DSM-IV).
Sleep Disturbance was characterized using three clinician-rated insomnia questions (early, middle, and late insomnia) on the HDRS. Based on a similar grouping procedure used by Naismith et al. (2009), participants were divided into two groups based on their insomnia scores; the “Sleep Disturbance” group was defined as scoring “2” or more on at least two of the three sleep items, whereas the “No Sleep Disturbance” group included the remaining participants. The specificity of this grouping criteria intended to capture only those patients with severe sleep disturbance occurring over multiple periods through the night.
Cognitive Functioning was assessed using raw scores for: Learning (Hopkins Verbal Learning Test; Learning; HVLT-L) (Wechsler Memory Scale; Logical Memory-Immediate Recall; WMS-L) (Brief Visuospatial Memory Test; Immediate Recall; BVMT-R) and Memory (Hopkins Verbal Learning Test; Delayed Recall; HVLT-M) (Wechsler Memory Scale; Logical Memory-Delayed Recall; WMS-M) (Brief Visuospatial Memory Test; Delayed Recall, BVMT-R).
DATA ANALYTIC PROCEDURE:
Analyses of Covariance (ANCOVA) were conducted to compare the two Sleep Disturbance groups with respect to immediate/working memory and long- term/delayed memory, co-varying for potentially relevant demographic factors (age, education). Convergent validity was also analyzed through correlation of composite HDRS insomnia scores to another self-report instrument for sleep disturbance (question #30 on the Katz Activities of Daily Living questionnaire). All statistical tests were conducted using IBM SPSS Statistics Desktop 21.0.
Figure 2: Learning Performance Across Groups
p = 0.12
Table 1: Demographic Characteristics
Sleep Disturbance
No Sleep Disturbance n
Mean (sd) F p
Age
 21
71.5 (6.6)
49 
72.0 (6.1)
.08
.78
Education 21
15.7 (2.8)
16.0 (2.6)
.15
.70 %
Gender (f) 80
 49 75
.00
p = 0.24
p = 0.47
DISCUSSION:
Our findings suggest that sleep disturbance in LLD is associated with deficits in delayed verbal memory, but not learning. The authors conjecture that consistently interrupted sleep in LLD may disrupt daytime consolidation of verbal information to long-term memory and/or disrupt verbal memory retrieval following normal encoding. One limitation of these findings is that the authors did not control for multiple comparisons and did not screen for other sleep disorders like Sleep Apnea. The findings are also limited by the sole use of clinician-rated sleep measures for classifying sleep disturbance. Future studies should also include objective sleep measures, such as polysomnography, to confirm and/or corroborate findings. Nevertheless, the HDRS sleep items were found to be a reasonably valid measure of sleep disturbance when correlated with the self-reported sleep disturbance rating on the Katz Questionnaire. More importantly, HDRS sleep items are also simple to administer for screening purposes and already commonly administered in most depression assessment paradigms.
CONCLUSION:
Our findings suggest that a convenient screening method for sleep disturbance that uses items from the HDRS may assist clinicians in identifying depressed older adults with severe sleep disturbance who may be at risk for poor performance on measures of delayed verbal recall. Further, the findings perhaps imply that more aggressive management of sleep disturbance might also improve verbal memory in LLD.
References:
Cricco, M., Simonsick, E. M., & Foley, D. J. (2002). The impact of insomnia on cognitive functioning in older adults. Journal of the American Geriatrics Society, 49(9),
Naismith, S. L., Norrie, L., Lewis, S. J., Rogers, N. L., Scott, E. M., & Hickie, I. B. (2009). Does sleep disturbance mediate neuropsychological functioning in older people with depression?. Journal of affective disorders, 116(1),
Park, S. C., Kim, J. M., Jun, T. Y., Kim, J. B., Jeong, S. H., & Park, Y. C. (2013). Prevalence and clinical correlates of insomnia in depressive disorders: The Crescend Study. Psychiatric Investigations, 10(4).
Figure 1: Delayed Recall Performance Across Groups
p = 0.035*
p = 0.008*
p = 0.28
HVLT = Hopkins Verbal Learning Test, delayed total correct, WMS = Wechsler Memory Scale Delayed Recall, BVMT = Brief Visuospatial Memory Test