title: Sleep problems associated with behavioral and psychological symptoms as well as cognitive functions in Alzheimer's disease.
abstract: OBJECTIVE
  It has been shown that sleep problems in Alzheimer's disease (AD) are associated with cognitive impairment and behavioral problems. In fact, most of studies have founded that daytime sleepiness is significantly correlated with cognitive decline in AD. However, a few studies have also shown that nighttime sleep problems are associated with cognitive function and behavioral symptoms in AD. Accordingly, the aim of this study was to evaluate the effects of nighttime sleep on cognition and behavioral and psychological symptoms of dementia (BPSD) in AD.
  
  
  METHODS
  The study population comprised 117 subjects: 63 AD patients and 54 age- and sex-matched non-demented elderly subjects. Detailed cognitive functions and behavioral symptoms were measured using the Seoul Neuropsychological Screening Battery (SNSB) and the Korean version of the Neuropsychiatric Inventory (NPI-K). Sleep characteristics were evaluated using the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K). The correlations between PSQI-K and SNSB scores and between PSQI-K and NPI-K scores were analyzed.
  
  
  RESULTS
  In AD patients, sleep latency was found to be negatively correlated with praxis (p=0.041), Rey-Osterrieth Complex Figure Test (RCFT) immediate recall (p=0.041), and RCFT recognition (p=0.008) after controlling for age and education, while sleep duration and sleep efficiency were positively correlated with praxis (p=0.034 and p=0.025, respectively). Although no significant correlation was found between PSQI-K and NPI-K scores, sleep disturbance and total PSQI-K scores were found to be significantly associated with apathy/indifference in AD.
  
  
  CONCLUSIONS
  Sleep problems such as prolonged sleep duration, sleep latency, and poor sleep efficiency in AD patients were correlated with cognitive dysfunction, and especially frontal executive and visuospatial functions, and BPSD. These findings suggest that treatment of nighttime sleep problems might improve cognition and behavioral symptoms in AD patients.
authors.affiliation: Department of Neurology, Gachon University Gil Medical Center, Incheon, Korea.
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: Shin
authors.affiliation: Department of Neurology, Myongji Hospital, Goyang, Korea.
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Han
authors.affiliation: Department of Neurology, Gachon University Gil Medical Center, Incheon, Korea.
authors.forename: Dong-Jin
authors.initials: DJ
authors.lastname: Shin
authors.affiliation: Department of Neurology, Gachon University Gil Medical Center, Incheon, Korea.
authors.forename: Hyeon-Mi
authors.initials: HM
authors.lastname: Park
authors.affiliation: Department of Neurology, Gachon University Gil Medical Center, Incheon, Korea.
authors.forename: Yeong-Bae
authors.initials: YB
authors.lastname: Lee
authors.affiliation: Department of Neurology, Gachon University Gil Medical Center, Incheon, Korea.
authors.forename: Kee Hyung
authors.initials: KH
authors.lastname: Park
keywords: Alzheimer's disease; behavioral symptoms; cognition; sleep