Wakefulness And Parkinson’s Disease

The study previously mentioned also found a link between sleep deficit and other brain disorders including Parkinson’s disease. This disorder is characterised by destruction of the brain cells which produce a chemical messenger called dopamine.  In addition to other important functions, this substance is important in making the distinction between being asleep or awake.  Drugs like amphetamine, are known to stimulate dopamine activity, increasing wakefulness.

Sleep and our body clock

Although we live and work to a 24-hour day, our own internal body clock has its own cycle, known as circadian rhythm.  Studies have shown that before developing Alzheimer’s, the internal body clock of mice becomes disordered and the part of their brain which controls it is also where they lose brain cells in Alzheimer’s disease.  Genetic variations have been found which may predispose to disordering of circadian rhythm, and possibly also to degenerative brain diseases.

What is the significance of this research?

Although these studies seem to indicate a link between disrupted sleep and degenerative brain disorders, whether it is a causal link ie lack of sleep causes diseases like Alzheimer’s, has yet to be proven.  This could only be done by treating the sleep disturbance, such as apnoea, in one group of people at risk of developing Alzheimer’s while leaving a comparable group untreated.  But withholding a treatment would be considered unethical, so this type of trial is unlikely to happen.

So can nothing be done?

Although many of the studies so far have been in animals, David Holtzman feels that it will be shown to also apply in humans.  The good news is that he is confident that the link between sleep disruption and degenerative brain disease can be reversed:

Alpar Lazar, a researcher in sleep and neurodegenerative diseases at the University of Cambridge, agrees as he has found that sleep disturbance worsens, the closer people are to their diagnosis of Parkinson’s Disease. Even long before that diagnosis their sleep disturbance is much worsethan in people who do not develop the disease.  He said:

Is there any proof this will work?

It’s early days, but there are some seeds of hope from people treated for sleep apnoea. When they are successfully treated so that they get a good night’s sleep and are not drowsy the next day they are more cheerful and memory and brain function have been shown to be improved.  The hope is that treating sleep disorders might not only prevent or delay onset of brain diseases, but also slow down normal age-related cognitive decline.

As people are now surviving to much greater ages, this could be important in preserving quality of life into those advanced years.