Deconstructing mental illness through ultradian rhythms
News Feb 22, 2015
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 neurotransmitter. 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.
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.
Note: Material may have been edited for length and content. For further information, please contact the cited source.
Ian D. Blum, Lei Zhu, Luc Moquin, Maia V. Kokoeva, Alain Gratton, Bruno Giros, Kai-Florian Storch. A highly tunable dopaminergic oscillator generates ultradian rhythms of behavioral arousal. eLife, Published December 29 2014. doi: 10.7554/eLife.05105
Adult depression has long been associated with shrinkage of the hippocampus, a brain region that plays an important role in memory and response to stress. Now, new research has linked participation in team sports to larger hippocampal volumes in children and less depression in boys ages 9 to 11.
Researchers have discovered a brain process common to sleep and ageing in research that could pave the way for new treatments for insomnia. The scientists report how oxidative stress leads to sleep. Oxidative stress is also believed to be a reason why we age and a cause of degenerative diseases.READ MORE
Patients in a new Northwestern Medicine study were able to comprehend words that were written but not said aloud. They could write the names of things they saw but not verbalize them. This provides an insight into the brain degeneration that defines the rare dementia termed primary progressive aphasia.