DECONSTRUCTING MENTAL ILLNESS THROUGH ULTRADIAN RHYTHMS
Might living a
structured life with regularly established meal times and early bedtimes lead
to a better life and perhaps even prevent the onset of mental illness? That's
what's suggested in a study led by Kai-Florian Storch, PhD, of the Douglas
Mental Health University Institute and McGill University, which has been
published in the online journal eLife
Our daily sleep-wake
cycle is governed by an internal 24-hour timer, the circadian clock. However,
there is evidence that daily activity is also influenced by rhythms much
shorter than 24 hours, which are known as ultradian rhythms and follow a
four-hour cycle. Most prominently observed in infants before they are able to
sleep through the night, ultradian rhythms may explain why, on average, we eat
three meals a day that are relatively evenly spaced across our daily wake
period.
These four-hour
ultradian rhythms are activated by dopamine, a key chemical substance in the
brain. When dopamine levels are out of kilter -- as is suggested to be the case
with people suffering from bipolar disease and schizophrenia -- the four-hour
rhythms can stretch as long as 48 hours.
A novel hypothesis
With this study,
conducted on genetically modified mice, Dr. Storch and his team demonstrate
that sleep abnormalities, which in the past have been associated with circadian
rhythm disruption, result instead from an imbalance of an ultradian rhythm
generator (oscillator) that is based on dopamine. The team's findings also
offer a very specific explanation for the two-day cycling between mania and
depression observed in certain bipolar cases: it is a result of the dopamine
oscillator running on a 48-hour cycle.
Groundbreaking
This work is
groundbreaking not only because of its discovery of a novel dopamine-based
rhythm generator, but also because of its links to psychopathology. This new
data suggests that when the ultradian arousal oscillator goes awry, sleep
becomes disturbed and mania will be induced in bipolar patients; oscillator
imbalance may likely also be associated with schizophrenic episodes in
schizophrenic subjects. The findings have potentially strong implications for
the treatment of bipolar disease and other mental illnesses linked to dopamine
dysregulation.
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