Original articleSleep disturbance in mild to moderate Alzheimer's disease
Introduction
Sleep disturbance in Alzheimer's disease (AD) is common. Cross-sectional studies of clinic- and community-based studies have reported that up to 40% of patients with AD have sleep disturbance [1].
The cause of sleep disturbance in AD is thought to be multi-factorial. Pathophysiological changes resulting from the disease itself interfere with the maintenance of normal sleep. Damage to neuronal pathways, such as the cholinergic pathways, that initiate and maintain sleep is thought to contribute to sleep changes in AD [2]. The circadian pacemaker, in the suprachiasmatic nucleus, is also important in maintaining a normal sleep-wake cycle. Researchers have demonstrated dysregulation of the circadian timing system in AD, and this may play a role in the development of sleep disturbance [3].
Sleep disturbance is also known to occur as part of associated medical and psychiatric illnesses, such as chronic obstructive airways disease, arthritis, nocturia, and depression, which are frequently diagnosed in patients with AD [4].
For patients with dementia, sleep disturbance will reduce quality of life, and some reports suggest that it is associated with cognitive and functional decline [5], [6]. For caregivers, sleep disturbance is a source of physical and psychological burden and is often cited as a reason for a family's decision to institutionalise a patient [7], [8].
It is therefore important that sleep disturbance in AD is recognised and treated appropriately. Recognition of associated symptoms may help in determining the cause of sleep disturbance in AD. It may also assist the clinician in choosing an appropriate treatment and reduce the likelihood of polypharmacy.
The aim of this study is to determine the prevalence of sleep disturbance in a memory clinic population of patients with AD and identify its clinical correlates.
Section snippets
Method
The sample was recruited through Mercer's Institute for Research on Ageing (MIRA), a national referral centre for people with memory difficulties. All first-appointment attendees who fulfilled the National Institute for Neurological and Communicative Disorders/Alzheimer's Disease and Related Disorders Association (NINCDS/ADRDA) consensus criteria for probable AD were included [9]. This consensus diagnosis was assigned at a Consultant Geriatrician and Consultant Psychogeriatrician led consensus
Results
Fifty-eight percent of the sample lived with their informant, and 94.2% were first-degree relatives of their informant. There was no difference in the sleep-disturbed compared to the non-sleep-disturbed group in terms of relationship to informant.
Of the 224 people evaluated 55 (24.5%) had sleep disturbance. The mean age of the sample was 74.91 years (SD=7.74). There was no significant difference between the sleep-disturbed and the non-sleep-disturbed group with regard to age (95%
Discussion
Before discussing these results it is important to address methodological issues.
While the BEHAVE-AD is a well established and widely used tool for assessing behavioural and psychological symptoms of AD it is not an ideal tool for assessing sleep disturbance. It provides limited information on sleep maintenance, and no detail of sleep times or other sleep parameters. It is important to remember this when considering the findings. Unfortunately to date there is no sleep questionnaire validated
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