are all mental illnesses related to circadian rhythm disruption?
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the survival of all living organisms, according to researchers, depends on an uninterrupted sleep-wake cycle. getty
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anxiety, autism and schizophrenia may have more in common than we think, according to a team of scientists that argue the entire spectrum of mental illness is related to disruptions in our circadian rhythm.
in the article published in the journal translational psychiatry, the group posits that circadian rhythm disruption (crd) is a psychopathology factor shared by a wide range of mental health disorders and gaining a better understanding of the molecular processes underpinning the sleep-wake cycle could open the door to new therapies and treatments for patients.
“circadian rhythms play a fundamental role in all biological systems at all scales, from molecules to populations,” said pierre baldi, senior author of the study and university of california, irvine (uci) distinguished professor of computer science. “our analysis found that circadian rhythm disruption is a factor that broadly overlaps the entire spectrum of mental health disorders.”
in addition to determining when we sleep and rise, circadian rhythms are responsible for a range of vital functions, including regulating the body’s physiological activity and many of its biological processes. they also play a role in hormone production and release, the consolidation of memories and the maintenance of body temperature. the survival of all living organisms, according to the team, depends on an uninterrupted sleep-wake cycle.
although testing their theory at a molecular level presents challenges, researchers found plenty of supporting evidence for the role crd plays in the most common mental illnesses in peer-reviewed literature. “the telltale sign of circadian rhythm disruption — a problem with sleep — was present in each disorder,” said amal alachkar, lead author and a neuroscientist and professor of teaching in uci’s department of pharmaceutical sciences.
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“while our focus was on widely known conditions, including autism, adhd and bipolar disorder, we argue that the crd psychopathology factor hypothesis can be generalized to other mental health issues, such as obsessive-compulsive disorder, anorexia nervosa, bulimia nervosa, food addiction and parkinson’s disease.”
the team noted that circadian rhythms operate as a natural timekeeping system and are highly sensitive to light and dark cues in a way that appears to be dependent on both sex and age. this is evident in the hormonal response pregnant women have to disruptions in the sleep-wake cycle, which can leave both mother and fetus feeling clinical effects from crd and chronic stress.
“an interesting issue that we explored is the interplay of circadian rhythms and mental disorders with sex,” baldi said. “for instance, tourette syndrome is present primarily in males, and alzheimer’s disease is more common in females by a ratio of roughly two-thirds to one-third.”
the big, unanswered question, according to baldi, is whether the relationship between crd and mental illness is one of correlation or causation. that is, does crd play a key role in the onset of mental illness or is it a self-reinforcing symptom in the progression of disease?
finding the answer won’t be easy.
“this will be a high-throughput process with researchers acquiring samples from healthy and diseased subjects every few hours along the circadian cycle,” baldi said. “this approach can be applied with limitations in humans, since only serum samples can really be used, but it could be applied on a large scale in animal models, particularly mice, by sampling tissues from different brain areas and different organs, in addition to serum. these are extensive, painstaking experiments that could benefit from having a consortium of laboratories.”
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if successful, however, this research could one day identify potential biomarkers, causal relationships and new avenues of treatment for patients suffering from the full spectrum of mental illness.
dave yasvinski is a writer with healthing.ca
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