Apathy, Sleep Disturbance, and the CLOCK Gene among Persons with Alzheimer’s Disease

Student Author(s)

Jamie Johnson

Faculty Mentor(s)

Dr. Emilie Dykstra Goris, Nursing, Dr. Vicki Voskuil, Nursing

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Sleep disturbance and apathy are common symptoms among persons with Alzheimer’s disease (AD). The Circadian Locomotor Output Cycles Kaput (CLOCK) gene assists in regulating circadian rhythms and prosocial behaviors. Additional research is needed to better understand how the CLOCK gene modifies these patterns in persons with AD. This study was based on the Need-Driven Dementia-Compromised Behavior Model that focuses on understanding difficult behaviors, including sleep disturbance and apathy. The first aim of this comparative study was to amplify a specific region of the CLOCK gene containing the single nucleotide polymorphism (SNP) of interest, rs6832769, using real time polymerase chain reaction. The second aim was to analyze relationships between genotype data and phenotype data, including sleep disturbance and apathy subscales of the Neuropsychiatric Inventory (NPI). Allelic discrimination was used to determine genotype frequency among 115 persons with AD from institutional facilities and community settings. Frequency of genotypes was as follows: AA genotype: n=53 (46%); AG genotype: n=37 (32%); GG genotype: n=13 (11%). There were 12 undetermined samples. One-way ANOVA was conducted using SPSS Version 23 to compare mean apathy severity score by genotype. A trend emerged between apathy severity and CLOCK gene SNP rs6832769, where persons with the GG genotype were less likely, though not significantly, to display more severe apathy (F=0.07, df=2, p=0.93). The study was limited by testing only one SNP and by sample size, as there was only NPI data for a subset of 48 of the 115 participants with very few experiencing sleep disturbance (n=8). With further investigation, targeted nonpharmacological nursing interventions may be used within this population to promote more regular sleep schedules and to reduce apathy.

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