1.3 million patient genetics study identifies brain cells involved in insomnia.

Insomnia, also known as sleeplessness, is a sleep disorder where people have difficulty falling asleep, or staying asleep for a healthy amount of time, with over 770 million people suffering from chronic insomnia worldwide.  Currently there is no sufficient treatment available for insomnia and despite evidence pointing towards heritability, research into the associated genes and neurobiological pathways remains limited.  Now, a study from researchers led by VU Amsterdam identifies the cell types, regions and biological processes in the brain which mediate the genetic risk of insomnia.  The team state their study, which assesses DNA and sleep features in over 1.3 million people, is a major step towards uncovering the biological mechanisms which cause insomnia. The opensource study is pre-printed in bioRxiv and published in the journal Nature Genetics.

Previous studies show insomnia can occur independently or as a result of another problem.  A multitude of conditions can result in insomnia such as psychological stress, chronic pain, heart failure, menopause, certain medications, and drugs like caffeine, nicotine, and alcohol.  And while treatment for insomnia alleviates symptoms, most sufferers describe feeling vulnerable to experiencing poor nights of sleep. This suspectibility to insomnia is known to run in families and appears to be hard-wired in the brain with only a few of the genes involved identified. It has also remained unclear where in the brain insomnia risk genes exert their disturbing role, knowledge which would be crucial to developing better treatments.  The current study performs genetic analysis on a 1.3 million cohort to allow detection of genetic variants, biological functions, cell types and tissues involved in insomnia.

The current study analyses genetic data from 1.3 million people, the largest genetic dataset ever, obtained from the UKBiobank and 23andMe databases to find out where in the brain insomnia risk genes exert their effect.  Results identified 956 genes utilised by specific biological processes, cell types and brain areas, whose variants contributed to the risk of insomnia.  Data findings show involvement of the axonal part of neurons, of specific cortical and subcortical tissues, and of two specific cell-types in insomnia, namely, striatal medium spiny neurons and hypothalamic neurons. These cell-types have been implicated in the regulation of reward processing, sleep and arousal in animal studies, this is the first time they have been genetically linked to insomnia in humans.

The lab explain that insomnia, like so many other neuropsychiatric disorders, is influenced by 100’s of genes, each of which has a small effect.  They go on to add that these genes by themselves are not that interesting to look at, however, when combined they grossly effect the risk of insomnia; these findings are a breakthrough, as the global medical community can now start searching for underlying mechanisms in individual brain cells in regards to insomnia.

The team surmise their findings provide novel insight into the pathology of insomnia, implicating specific cell types, brain areas and biological functions.  For the future, the researchers state their data is a starting point for the development of new therapeutic targets for insomnia and may also provide valuable insights for other genetically related disorders.

Source: VU Amsterdam


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