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Assessing and Treating Sleep Disturbances in Patients With Alzheimer's Disease

Assessing and Treating Sleep Disturbances in Patients With Alzheimer's Disease

Psychiatric Times November 2005
Issue 13

Changes in sleep are inevitable as people age, though some sleep symptoms
may be due to diseases rather than aging itself (Foley et al., 1999). For
example, 41% of a study sample of older adults with ≥4 medical conditions
considered themselves to be fair or poor sleepers as compared to 22% with one
to three conditions and only 10% of those with none (Foley et al., 2004). In
this same study, poor sleep was most strongly associated with heart disease,
depression, arthritis and obesity. However, even healthy seniors experience
reductions in slow-wave sleep ("deep sleep") and have lower sleep efficiency
with more nighttime awakenings than younger adults (Bliwise,

Patients with Alzheimer's disease (AD) may have the same sleep disturbances
seen in other seniors, and, early in the course of AD, their sleep may not
differ markedly from age-matched controls (Vitiello
et al., 1990). In some cases, however, the sleep disturbance may be a marker
for early AD. For example, investigators have reported that insomnia is an
independent risk factor for cognitive decline over a three-year follow-up
period (Cricco et al., 2001). Sleep-related problems
generally increase as AD progresses (Moe et al., 1995). Patients with AD
experience more frequent nighttime awakenings, daytime sleep increases, and
both slow-wave sleep and rapid eye movement (REM) sleep are decreased (Bliwise, 1993; Prinz et al.,
1982; Vitiello and Borson,
2001; Vitiello et al., 1992). Subjective sleep
disturbances occur in up to 54% of patients with AD who live in the community
(Carpenter et al., 1995; Chen et al., 2000; Hart et al., 2003; McCurry et al., 1999). McCurry et
al. (1999) reported that 24% of caregivers report being awakened at night by
the patient with AD and 40% report that patients with AD sleep more than usual.

Sleep disturbances tend to occur in patients with AD and other neuropsychiatric symptoms, such as anxiety and psychosis
(Friedman et al., 1997; McCurry et al., 1999). Beyond
these symptoms, disruptive nighttime behaviors secondary to confusion often
develop, including nocturnal wandering, agitation, combativeness,
disorientation or even delirium (Bliwise, 1993). The
term sundowning
is sometimes used to refer to these nighttime behaviors and erroneously used as
a synonym for sleep disorder in
patients with AD, but sundowning and sleep disorders
are distinct syndromes. However, it is the nighttime behaviors while awake that
prove distressing to patients and caregivers alike and, indeed, have been
documented as the most significant contributing factor in institutionalization
of patients with AD (Gaugler et al., 2000; Hope et
al., 1998; Pollak and Perlick,
1991). In one study, caregivers reported that sleep disturbances were among the
most distressing of all AD-related symptoms (Hart et al., 2003). In fact, of
patients with AD who awaken their caregivers at night, 70% of the caregivers
reported the awakenings to be moderately to severely distressing (McCurry et al., 1999).

Daytime function of patients with AD may be adversely affected by poor
nighttime sleep, but there may also actually be a primary arousal problem in AD
that impairs daytime alertness. Daytime sleepiness may be an early
manifestation of AD, just as insomnia is. Adjusting for age and health status,
older adults with daytime sleepiness are more than twice as likely to develop
dementia after a three-year follow-up (Foley et al., 2001). Daytime sleepiness
clearly impacts daily function in non-demented older adults (Gooneratne et al., 2003) and can be logically presumed to
have at least as great an effect in patients with AD. Not surprisingly,
although 38% of caregivers report moderate-to-severe distress from hypersomnia, this percentage is only half that of
caregivers distressed by nighttime sleep disturbance (McCurry
et al., 1999).

Alzheimer's disease sleep investigators from several centers recently
proposed diagnostic criteria for defining the core sleep disturbance of AD (Yesavage et al., 2003). By defining diagnostic criteria for
insomnia and hypersomnia in patients with AD, the
authors provided clear diagnostic guidelines for clinical intervention and
research trials. Although patients with AD may experience all the sleep
disorders of old age--periodic limb movement, restless legs syndrome and
sleep-related breathing disorders--the proposed diagnostic criteria specify that
there is a primary sleep disturbance of AD. It is important to note, however,
that the sleep disturbances seen in AD are nonspecific and can also be seen in
other neurodegenerative conditions, such as vascular dementia, dementia with Lewy bodies (DLB) and Parkinson's disease. These other dementing diseases are also associated with high rates of
insomnia and daytime sleepiness. Parasomnias are also
more likely to occur in non-AD disorders. Some patients with dementia
experience loss of muscle atonia during REM sleep
that can result in dramatic motor activity and dream-enactment behavior. The
syndrome, called REM behavior disorder,
is not typically seen in AD, but is characteristic of DLB. Its development may
even precede the dementia (Boeve et al., 1998).

Biological Mechanisms


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