Huntington's Disease and Sleep
By
Prof Jenny Morton on February 06, 2013 Edited by
Dr Ed Wild
Many Huntington's disease patients have problems with sleep and in the control of daily or 'circadian' rhythms. These problems may actually be part of the range of symptoms in HD, and managing or treating them directly may be beneficial. In this special HDBuzz feature, sleep expert Prof Jenny Morton looks at the science behind sleep problems and solutions in Huntington's disease. Coming soon, part 2: Prof Morton's 'Simple Rules for a Good Night's Sleep'.
After a long day, many of us look forward to the bliss that comes with a good night's sleep. But not everyone who is tired is guaranteed a peaceful night's sleep. For those to whom sleep does not come, the night can seem a lonely and sometimes anguished exile. And more often than not, those who live with the sleepless share the burden. Unfortunately for the person with a neurological disease like Huntington's, the consequences of sleep disturbance may not only be distressing and disruptive, but may also contribute significantly to their symptoms
Neurological disease causes sleep problems
Sleep abnormalities and disorders of circadian rhythm are already recognized as symptoms in a number of other neurodegenerative diseases, particularly Parkinson's disease and Alzheimer's disease. In fact, sleep disruption in Alzheimer's patients is reportedly the main reason for their institutionalization. This is probably because when an Alzheimer's patient has disrupted sleep, this becomes a problem not only for the patient, but also for their carer.
More research is needed before we will know if sleep or circadian rhythm disruption is part of the complex repertoire of Huntington's disease symptoms, or if it is just a 'knock-on' effect of having HD. But whatever the cause, we should recognize that even mild sleep abnormalities could worsen neurological symptoms in HD patients. Knock-on effects of sleep abnormalities in HD may be critical for determining the care-plan of patients. And, if they worsen thinking and mood disturbances, they may also end up having a have greater impact on quality of life than other symptoms like involuntary movements.
Circadian abnormalities in Huntington's disease
The first clue that sleep or circadian rhythms might be abnormal in HD patients came from a study showing subtle changes incircadian activity profiles, measured by wrist-mounted movement monitors.
Circadian rhythms are difficult to measure accurately in humans, because the rhythm can be masked by other activities such as work and social life. But they are easy to measure in mice, and direct measurement of circadian rhythms in one HD mouse model showed clear abnormalities in circadian behavior.
These mice showed a progressive disintegration of the normal rhythm of rest and activity. That disturbance was mirrored in the HD patients wearing the activity monitors. In the HD mice, there was also disruption in activity levels of genes that controlled thecircadian clock in the SCN. These circadian abnormalities in HD mice have now been confirmed by three different laboratories.
Importantly, the breakdown in circadian rhythms in the mice were linked to their decline in thinking function - and restoring good circadian rhythms delayed the thinking decline.
This suggests that some of the thinking problems in the mice were caused by the disruption of sleep and circadian rhythm. If the same thing happens in humans, then improving sleep and circadian function might have a beneficial effect on cognitive and emotional problems in people with Huntington's disease.
Source:
http://en.hdbuzz.net/115