Neurology

Raman Malhotra, MD, on the Connection Between Sleep Disorders and Neurodegenerative Diseases

Research has shown a strong association between sleep disorders and neurodegenerative diseases. As our understanding of this connection deepens, it becomes even more important to monitor for sleep disorders and their effect on neurocognition.

Circadian rhythm, sleep disorders, and neurodegenerative disease was the topic of discussion during a session at the American Neurological Association’s 2019 Annual Meeting.1 Speaker Raman Malhotra, MD—who is an associate professor of neurology at the Washington University Sleep Medicine Center in St. Louis, Missouri—answered our questions about his session and the growing knowledge base of the connection between sleep and brain function.

NEUROLOGY CONSULTANT: What is the association between circadian rhythm and neurodegenerative diseases?

Raman Malhotra: My session reviewed emerging data looking at the association between poor sleep and neurodegenerative conditions such as Parkinson disease (PD) and Alzheimer disease (AD). As the underlying neurodegenerative condition progresses, sleep also tends to worsen. Currently, clinicians improve sleep in patients with AD and PD through diagnosis and treatment of primary sleep disorders, such as insomnia and sleep apnea, to improve overall functioning and quality of life.

However, there is mounting interest in evaluating how poor sleep earlier in life could lead to future development of AD in preclinical or asymptomatic populations. Increasing evidence suggests that sleep disruption in patients with early or even preclinical AD contributes to its onset and progression. Circadian rhythm disorders are common among patients with  neurodegenerative disorders and may play a role in accelerating progression of these disorders of the brain. Circadian disruption may predispose the brain to neurodegenerative conditions by altering immune function, disrupting endocrine function, increasing inflammation and oxidative stress, or affecting neurogenesis. Sleep symptoms can also be a precursor of other neurological diseases. One example is dream enactment (such as rapid eye movement [REM] sleep behavior disorder) that can precede onset of neurodegenerative disease (such as PD) by decades. Thus, inadequate sleep could prime the brain for neurodegeneration by multiple pathways.

NEURO CON: Which neurodegenerative diseases are most common among patients with sleep disorders?

RM: Patients with REM sleep behavior disorder are much more likely to develop a synucleinopathy (such as PD) than the general population. One study have found the risk to be 6.3% per year, with 73.5% at 12-year follow-up.2 Ultimately, up to 90% convert to a synucleinopathy over time.

NEURO CON: How can neurologists and sleep specialists better care for their patients with sleep disorders and neurodegenerative disease?

RM: It is important to properly recognize and treat underlying sleep disorders in patients with neurodegenerative conditions. Sleep disorders such as sleep apnea, insomnia, and restless legs syndrome are very common among these patients. Treating these conditions and, ultimately, getting better-quality sleep leads not only to more alertness and wakefulness during the day but may also help improve other underlying symptoms associated with the neurodegenerative condition, such as motor or cognitive deficits.

NEURO CON: What is the key take-home message from your session?

RM: We already have evidence that treating sleep disorders in patients with neurodegenerative diseases such as AD and PD can help improve sleep quality and quality of life. However, we are now learning that sleep may play an important role in onset or acceleration of the underlying pathophysiological process. These new findings make it even more important to ask patients about their sleep habits when they present to the neurology clinic.

For more information about the ANA’s Annual Meeting or to read more about Dr Malhotra’s session, visit the ANA’s website: https://2019.myana.org.

Reference:

  1. Malhotra R. Sleep clocks, disorders, and neurodegenerative disease. Talk presented at: American Neurological Association 2019; October 13-15, 2019: St. Louis, MO. https://2019.myana.org/sites/default/files/docs/2019/ana19_advanceprogram.pdf.
  2. Postuma RB, Iranzo A, Hu M, et al. Risk and predictors of dementia and Parkinsonism in idiopathic REM sleep behaviour disorder: a multicentre study. Brain. 2019;142(3):744-759. https://doi.org/10.1093/brain/awz030.