A healthy lifestyle that involves moderate alcohol consumption, a healthy diet, regular physical activity, healthy sleep and frequent social connection, while avoiding smoking and too much sedentary behaviour, reduces the risk of depression, new research has found.
Although our DNA – the genetic hand we’ve been dealt – can increase our risk of depression, we’ve shown that a healthy lifestyle is potentially more important.
Barbara Sahakian
In research published today in Nature Mental Health, an international team of researchers, including
from the University of Cambridge and Fudan University, looked at a combination of factors including
lifestyle factors, genetics, brain structure and our immune and metabolic systems to identify the
underlying mechanisms that might explain this link.
According to the World Health Organization, around one in 20 adults experiences depression, and the
condition poses a significant burden on public health worldwide. The factors that influence the onset of
depression are complicated and include a mixture of biological and lifestyle factors.
To better understand the relationship between these factors and depression, the researchers turned to
UK Biobank, a biomedical database and research resource containing anonymised genetic, lifestyle and
health information about its participants.
By examining data from almost 290,000 people – of whom 13,000 had depression – followed over a nine-year period, the team was able to identify seven healthy lifestyle factors linked with a lower risk of
depression. These were:
moderate alcohol consumption
healthy diet
regular physical activity
healthy sleep
never smoking
low-to-moderate sedentary behaviour
frequent social connection
Of all of these factors, having a good night’s sleep – between seven and nine hours a night – made the
biggest difference, reducing the risk of depression, including single depressive episodes and treatment-
resistant depression, by 22%.
Frequent social connection, which in general reduced the risk of depression by 18%, was the most
protective against recurrent depressive disorder.
Moderate alcohol consumption decreased the risk of depression by 11%, healthy diet by 6%, regular
physical activity by 14%, never smoking by 20%, and low-to-moderate sedentary behaviour by 13%.
Based on the number of healthy lifestyle factors an individual adhered to, they were assigned to one of
three groups: unfavourable, intermediate, and favourable lifestyle. Individuals in the intermediate group
were around 41% less likely to develop depression compared to those in the unfavourable lifestyle, while
those in the favourable lifestyle group were 57% less likely.
The team then examined the DNA of the participants, assigning each a genetic risk score. This score was
based on the number of genetic variants an individual carried that have a known link to risk of depression.
Those with the lowest genetic risk score were 25% less likely to develop depression when compared to
those with the highest score – a much smaller impact than lifestyle.
In people at high, medium, and low genetic risk for depression, the team further found that a healthy
lifestyle can cut the risk of depression. This research underlines the importance of living a healthy
lifestyle for preventing depression, regardless of a person’s genetic risk.
Professor Barbara Sahakian, from the Department of Psychiatry at the University of Cambridge, said:
“Although our DNA – the genetic hand we’ve been dealt – can increase our risk of depression, we’ve
shown that a healthy lifestyle is potentially more important.
“Some of these lifestyle factors are things we have a degree control over, so trying to find ways to
improve them – making sure we have a good night’s sleep and getting out to see friends, for example –
could make a real difference to people’s lives.”
To understand why a healthy lifestyle might reduce the risk of depression, the team studied a number of
other factors.
First off, they examined MRI brain scans from just under 33,000 participants and found a number of
regions of the brain where a larger volume – more neurons and connections – was linked to a healthy
lifestyle. These included the pallidum, thalamus, amygdala and hippocampus.
Next, the team looked for markers in the blood that indicated problems with the immune system or
metabolism (how we process food and produce energy). Among those markers found to be linked to
lifestyle were the C-reactive protein, a molecule produced in the body in response to stress, and
triglycerides, one of the primary forms of fat that the body uses to store energy for later.
These links are supported by a number of previous studies. For example, exposure to stress in life can
affect how well we are able to regulate blood sugar, which may lead to a deterioration of immune function and accelerate age-related damage to cells and molecules in the body. Poor physical activity and lack of sleep can damage the body’s ability to respond to stress. Loneliness and lack of social support have been found to increase the risk of infection and increase markers of immune deficiency.
The team found that the pathway from lifestyle to immune and metabolic functions was the most
significant. In other words, a poorer lifestyle impacts on our immune system and metabolism, which in
turn increases our risk of depression.
Dr Christelle Langley, also from the Department of Psychiatry at the University of Cambridge, said:
“We’re used to thinking of a healthy lifestyle as being important to our physical health, but it’s just as
important for our mental health. It’s good for our brain health and cognition, but also indirectly by
promoting a healthier immune system and better metabolism.”
Professor Jianfeng Feng, from Fudan University and Warwick University, added: “We know that
depression can start as early as in adolescence or young adulthood, so educating young people on the
importance of a healthy lifestyle and its impact on mental health should begin in schools.”