Physical activity may protect against new episodes of depression
November 5, 2019
Science Daily/Massachusetts General Hospital
Increased levels of physical activity can significantly reduce the odds of depression, even among people who are genetically predisposed to the condition, according to a new study from researchers at Massachusetts General Hospital (MGH). In a paper published in the journal Depression and Anxiety, the team reported that individuals who engaged in at least several hours of exercise each week were less likely to be diagnosed with a new episode of depression, even in the face of high genetic risk for the disorder.
Drawing on genomic and electronic health record data from nearly 8,000 participants in the Partners Healthcare Biobank, the new study is the first to show how physical activity can influence depression despite genetic risk. Researchers followed patients who filled out a survey about their lifestyle habits (including physical activity) when they enrolled in the Biobank. They then mined millions of electronic health record data points over the next two years and identified people who received diagnoses related to depression. They also calculated genetic risk scores for each participant, combining information across the entire genome into a single score that reflects a person's inherited risk for depression.
What they found was that people with higher genetic risk were more likely to be diagnosed with depression over the next two years. Significantly, though, people who were more physically active at baseline were less likely to develop depression, even after accounting for genetic risk. In addition, higher levels of physical activity were protective for people even with the highest genetic risk scores for depression.
"Our findings strongly suggest that, when it comes to depression, genes are not destiny and that being physically active has the potential to neutralize the added risk of future episodes in individuals who are genetically vulnerable," says Karmel Choi, PhD, of MGH and the Harvard T.H. Chan School of Public Health, and lead author of the study. "On average, about 35 additional minutes of physical activity each day may help people to reduce their risk and protect against future depression episodes."
The researchers found that both high-intensity forms of activity, such as aerobic exercise, dance and exercise machines, and lower-intensity forms, including yoga and stretching, were linked to decreased odds of depression. Overall, individuals could see a 17 percent reduction in odds of a new episode of depression for each added four-hour block of activity per week.
Depression represents the leading cause of disability worldwide. Despite its massive health burden, strategies to combat depression remain limited and the public's understanding of robust and modifiable protective factors is incomplete. "We provide promising evidence that primary care and mental health providers can use to counsel and make recommendations to patients that here is something meaningful they can do to lower their risk even if they have a family history of depression," says Choi.
Senior author Jordan Smoller MD, added, "In general our field has been lacking actionable ways of preventing depression and other mental health conditions. I think this research shows the value of real-world healthcare data and genomics to provide answers that can help us to reduce the burden of these diseases."
Beyond physical activity, the MGH team continues to leverage the Partners Biobank and other large-scale studies to explore modifiable ways that individuals might reduce their risk of depression. "We believe there may be many factors could be part of an overall strategy for improving resilience and preventing depression," emphasizes Choi. "The magnitude of depression around the world underscores the need for effective strategies that can impact as many people as possible."
https://www.sciencedaily.com/releases/2019/11/191105113510.htm
Exercise may improve thinking skills in people as young as 20
January 30, 2019
Science Daily/American Academy of Neurology
Regular aerobic exercise such as walking, cycling or climbing stairs may improve thinking skills not only in older people but in young people as well, according to a new study. The study also found that the positive effect of exercise on thinking skills may increase as people age.
The specific set of thinking skills that improved with exercise is called executive function. Executive function is a person's ability to regulate their own behavior, pay attention, organize and achieve goals.
"As people age, there can be a decline in thinking skills, however our study shows that getting regular exercise may help slow or even prevent such decline," said study author Yaakov Stern, PhD, of Columbia University in New York, and a member of the American Academy of Neurology. "We found that all participants who exercised not only showed improvements in executive function but also increased the thickness in an area of the outer layer of their brain."
The study involved 132 people between the ages of 20 and 67 who did not smoke or have dementia but who also did not exercise at the start of the study and were determined to have below average fitness levels. Participants were randomly assigned to six months of either aerobic exercise or stretching and toning four times a week. The two groups were equally balanced for age, sex, education as well as memory and thinking skills at the start of the study.
All participants either exercised or stretched and toned at a fitness center and checked in weekly with coaches monitoring their progress. They all wore heart rate monitors as well. Participants' thinking and memory skills were evaluated at the start of the study as well as at three months and at the end of the six-month study.
Participants in the exercise group chose from aerobic activities including walking on a treadmill, cycling on a stationary bike or using an elliptical machine. They ramped up their activity during the first month, then during the remainder of the six-month study they trained at 75 percent of their maximum heart rate. People in the stretching and toning group did exercises to promote flexibility and core strength.
Researchers measured participants' aerobic capacity using a cycling machine called an ergometer that estimates exercise intensity. Participants also had MRI brain scans at the start and end of the study.
Researchers found that aerobic exercise increased thinking skills. From the beginning of the study to the end, those who did aerobic exercise improved their overall scores on executive function tests by 0.50 points, which was a statistically significant difference from those who did stretching and toning, who improved by 0.25 points. At age 40, the improvement in thinking skills was 0.228 standard deviation units higher in those who exercised compared to those who did stretching and toning and at age 60, it was 0.596 standard deviation units higher.
"Since a difference of 0.5 standard deviations is equivalent to 20 years of age-related difference in performance on these tests, the people who exercised were testing as if they were about 10 years younger at age 40 and about 20 years younger at age 60," Stern said.
He added, "Since thinking skills at the start of the study were poorer for participants who were older, our findings suggest that aerobic exercise is more likely to improve age-related declines in thinking skills rather than improve performance in those without a decline."
Researchers also found an increase in the thickness of the outer layer of the brain in the left frontal area in all those who exercised, suggesting that aerobic exercise contributes to brain fitness at all ages.
"Our research confirms that exercise can be beneficial to adults of any age," said Stern.
Overall, researchers did not find a link between exercise and improved memory skills. However, those with the genetic marker for dementia, the APOE ?4 allele, showed less improvement in thinking skills.
A limitation of the study is the small number of participants. Larger studies over longer periods of time may allow researchers to see other effects in thinking and memory skills.
The study was supported by the National Institutes of Health.
https://www.sciencedaily.com/releases/2019/01/190130161638.htm