One hour
of exercise a week can prevent depression

Date:

October 3, 2017

Source:

University of New South
Wales

Summary:

Regular exercise of any intensity can
prevent future depression — and just one hour can help, a landmark study has
revealed.

A landmark study led by
the Black Dog Institute has revealed that regular exercise of any intensity can
prevent future depression — and just one hour can help.

Published in the American
Journal of Psychiatry, the results show even small amounts of exercise can
protect against depression, with mental health benefits seen regardless of age
or gender.

In the largest and most
extensive study of its kind, the analysis involved 33,908 Norwegian adults who
had their levels of exercise and symptoms of depression and anxiety monitored
over 11 years.

The international
research team found that 12 percent of cases of depression could have been
prevented if participants undertook just one hour of physical activity each
week.

“We’ve known for
some time that exercise has a role to play in treating symptoms of depression,
but this is the first time we have been able to quantify the preventative potential
of physical activity in terms of reducing future levels of depression,”
said lead author Associate Professor Samuel Harvey from Black Dog Institute and
UNSW.

“These findings are
exciting because they show that even relatively small amounts of exercise —
from one hour per week — can deliver significant protection against
depression.

“We are still trying
to determine exactly why exercise can have this protective effect, but we
believe it is from the combined impact of the various physical and social
benefits of physical activity.

“These results
highlight the great potential to integrate exercise into individual mental
health plans and broader public health campaigns. If we can find ways to
increase the population’s level of physical activity even by a small amount,
then this is likely to bring substantial physical and mental health
benefits.”

The findings follow the
Black Dog Institute’s recent Exercise Your Mood campaign, which ran throughout
September and encouraged Australians to improve their physical and mental
wellbeing through exercise.

Researchers used data
from the Health Study of Nord-Trøndelag County (HUNT study) — one of the
largest and most comprehensive population-based health surveys ever undertaken
— which was conducted between January 1984 and June 1997.

A healthy cohort of
participants was asked at baseline to report the frequency of exercise they
participated in and at what intensity: without becoming breathless or sweating,
becoming breathless and sweating, or exhausting themselves. At follow-up stage,
they completed a self-report questionnaire (the Hospital Anxiety and Depression
Scale) to indicate any emerging anxiety or depression.

The research team also
accounted for variables which might impact the association between exercise and
common mental illness. These include socio-economic and demographic factors,
substance use, body mass index, new onset physical illness and perceived social
support.

Results showed that
people who reported doing no exercise at all at baseline had a 44% increased
chance of developing depression compared to those who were exercising one to
two hours a week.

However, these benefits
did not carry through to protecting against anxiety, with no association
identified between level and intensity of exercise and the chances of developing
the disorder.

According to the
Australian Health Survey, 20 percent of Australian adults do not undertake any
regular physical activity, and more than a third spend less than 1.5 hours per
week being physically active. At the same time, around 1 million Australians
have depression, with one in five Australians aged 16-85 experiencing a mental
illness in any year.

“Most of the mental
health benefits of exercise are realised within the first hour undertaken each
week,” said Associate Professor Harvey.

“With sedentary
lifestyles becoming the norm worldwide, and rates of depression growing, these
results are particularly pertinent as they highlight that even small lifestyle
changes can reap significant mental health benefits.”

Story Source:

Materials provided by University of New South Wales. Note: Content may be
edited for style and length.

Journal Reference:

1.    Samuel B. Harvey, Simon
Øverland, Stephani L. Hatch, Simon Wessely, Arnstein Mykletun, Matthew Hotopf. Exercise
and the Prevention of Depression: Results of the HUNT Cohort Study. American
Journal of Psychiatry, 2017; appi.ajp.2017.1 DOI: 10.1176/appi.ajp.2017.16111223