Article from the Daily Mail below
Out of sync with the world: Depressed people suffer with 'broken body clocks'
- There is a link between depression and changes in the body's circadian rhythm, or body clock
- There is a daily rhythm to the activity of many genes across many different areas of the brain
- The pattern of gene activity is so distinctive that it can be used to estimate the hour of someone's death
- In people with depression clock is so disrupted that day pattern of gene activity can look like night pattern
The discovery of disrupted body clocks in the brains of people with depression is the first link to be found between the condition and changes in the circadian rhythm.
It is hoped that the finding will allow for the development of better treatments.
Every cell in the human body runs on a 24-hour clock, tuned to the night-day, light-dark cycles in nature.
The brain acts as a timekeeper, keeping this cellular clock in sync with the outside world so that it can govern our appetite, sleep and moods.
However, new research shows that the clock may be broken in the brains of people with depression - even at the level of the gene activity inside their brain cells.
The discovery, published in the journal, Proceedings of the National Academy of Sciences was made by studying differences in the donated brains of people who had been depressed and those who had not.
The research also revealed a previously unknown daily rhythm to the activity of many genes across many areas of the brain - expanding the sense of how crucial the body’s clock is.
In a normal brain, the pattern of gene activity at a given time of the day is so distinctive that the authors could use it to accurately estimate the hour of death of the brain donor.
However, in severely depressed patients, the circadian clock was so disrupted that a patient’s ‘day’ pattern of gene activity could look like a ‘night’ pattern, and vice versa.
Lead author Dr Jun Li, an assistant professor in the Department of Human Genetics at University of Michigan Medical School, in the U.S., described how the approach allowed the researchers to accurately back-predict the hour of the day when each non-depressed individual died - literally plotting them out on a 24-hour clock by noting which genes were active at the time they died.
They looked at 12,000 gene transcripts isolated from six regions of 55 brains from people who did not have depression. This provided a detailed understanding of how gene activity varied throughout the day in the brain regions studied.
Dr Li said: ‘There really was a moment of discovery.
‘It was when we realised that many of the genes that show 24-hour cycles in the normal individuals were well-known circadian rhythm genes - and when we saw that the people with depression were not synchronised to the usual solar day in terms of this gene activity.
‘It’s as if they were living in a different time zone than the one they died in.’
Depression affects one in ten adults in the UK at any one time but it is slightly more common in women.
At any one time one in 20 people in the UK will be experiencing severe depression.
The main symptoms are lasting feelings of sadness and hopelessness, losing interest in things you used to enjoy and feeling tearful.
There can also be physical symptoms such as fatigue, sleeping badly, having no appetite and aches and pains.