Link found between exercise, anxiety, and depression

The healthcare company Kaiser Permanente (KP) led the study, which involved people from Hawaii, Colorado, Georgia, the mid-Atlantic states, and Southern and Northern California.

The researchers surveyed more than 20,000 people in April 2020 and at least three more times until July 2020. The participants, all of whom were enrolled in a KP plan, answered questions about their lifestyle, shared their electronic health records, and gave biospecimens.

Most of the respondents were retired and adhered to stay-at-home orders. White women aged 50 years and over constituted the majority.

After analyzing the data, the researchers saw that those who had exercised or spent more time outdoors had lower anxiety and depression scores.

They also found the following:

• The participants reported fewer symptoms of anxiety and depression over time.
• Females and younger people had higher anxiety and depression scores, while Asian and Black people had lower scores.
• Those who did not report doing any physical activity during lockdown had the highest depression and anxiety scores.

However, the research found that the people who had increased the time they spent outdoors by the greatest amount also reported the highest anxiety scores. This was consistent in all demographic groups. The researchers could not explain this finding.

Lead author Deborah Rohm Young, Ph.D., the director of the Division of Behavioral Research for the Kaiser Permanente Southern California Department of Research & Evaluation, told Medical News Today she expected that more physical activity, as well as more time outdoors in nature, would be associated with lower depression and anxiety scores.

“The data is very clear that the mind and the brain are healthier when we spend more time […] in nature, but [also] just outdoors in general,” said Dr. David A. Merrill, adult and geriatric psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center at Providence Saint John’s Health Center in Santa Monica, CA.

“There are studies that show that less time outdoors leads to brain atrophy, over time and with age,” he added.

Dr. Bert Mandelbaum, sports medicine specialist, orthopedic surgeon, and co-chair of medical affairs at Cedars-Sinai Kerlan-Jobe Institute in Los Angeles, told MNT that the study was comprehensive and measured a lot of different aspects before coming to a conclusion.

“At the end of the day, exercise activities and being outside are healthy behaviors that optimize people’s lives and decrease anxiety and depression,” he said.

However, Dr. Young pointed out some findings that surprised the team.

“I was surprised to observe that the depression/anxiety scores improved over time and also that both increasing and decreasing the amount of time spent outdoors was associated with higher depression and anxiety scores,” she said.

Dr. Merrill said that interpreting the findings was a bit complicated and involved a fair amount of conjecture.

One factor behind the discrepancies could be the lack of baseline levels of both physical activity and depression or anxiety scores from pre-pandemic times, he said.

Dr. Young said that not knowing how much time the respondents spent in nature prior to the pandemic was one of the limitations that could explain why more time outdoors was associated with a higher score of anxiety.

“It could be that people who spent less time outdoors did so because of adhering to the stay-at-home orders and felt deprived of their ability to be outdoors. Or that people who reported spending more time outdoors did so because they were experiencing poor mental well-being,” she said.

Dr. Mandelabum, however, said that this should not detract from the main finding of the study.

“I would focus more on the fact that [more people] improved by going outside, being in nature, and exercising in a high intensity way, which optimizes anxious and depressed states. [T]he real conclusion is the importance of physical activity and being outdoors,” he said.

Dr. Young noted that other findings were mostly consistent with earlier research.

“Many previous studies have documented that females tend to have higher anxiety and depression scores than males. There are also a number of studies suggesting that older adults have better mental well-being than younger adults,” she told MNT.

The research attributed the latter to adults having lived through more adversity and having more experience in dealing with stress.

According to Dr. Merrill, the new study highlights an important issue. He said that his colleagues have seen a disproportionate number of adolescent patients facing challenges with their mental health since the pandemic.

“The data is confirmation of the experience of mental health clinicians working in these populations — that younger adults, in particular, have struggled during the pandemic with disruption of their normal activities, [having been ordered to] stay at home, restricted from being in outdoor public spaces. This really comes out in the data that these restrictions had a significant negative effect on people’s well-being,” he told MNT.

“Living through that disappointment of not being able to do something as normal as going to the park can be a very big setback for a young person who otherwise may have been just having a nontraumatic, normal upbringing and a normal life.”

– Dr. David A. Merrill

Dr. Young expressed some surprise at the racial differences in depression and anxiety scores.

“Asian Americans tend to report lower depression and anxiety compared with white people. On the other hand, Black people tend to have higher scores than white people, so this was unexpected, and I don’t believe it’s reflective of the general population,” she said.

She said this finding could be down to only 2.3{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of the cohort being Black adults.

“As far as the difference in the levels of depression and anxiety in terms of race and ethnicity, the data speaks for itself. There’s no definite explanation,” said Dr. Merrill.

For Dr. Mandelbaum, the tools that the team used to measure anxiety and depression levels might explain the finding.

“The tools, these objective measures, and the data pointed out cultural, racial differences. Looking at those in a nonbinary way can be misleading. I think the tools are limited because if you have 10 people in a room, and there are 10 people from 10 different countries, even if you’re asked the question in the same language, you will see how different people interpret it. These tools are very hard [to optimize] across different cultures or languages,” he said.

Meanwhile, Dr. Merrill said that the finding could possibly reflect an often overlooked reality for racial minorities.

“If you’re already more under stress based on systemic exclusion, or marginalization, [the pandemic may not have had] such a big impact. For a population who is already under stress, if you add on more stress, there may be less of a change compared with a group that has enjoyed privilege or a stress-free life. In the U.S., that kind of seems to be the reality,” he explained.

The study shows that future pandemics will need better planning and more careful thinking around people’s mental health. This could affect decisions to close down outdoor spaces, for instance.

Dr. Young acknowledged that fighting a novel virus has been tricky for all countries.

“I’m sure we all would like to have consistent messaging throughout the pandemic, but as the knowledge changes, so do the recommendations,” she said.

However, the study’s findings reiterate that even during an active pandemic, physical activity or spending time outdoors could help people maintain their physical and mental health.

“Governments should promote physical activity and spending time in nature during pandemics. Public health messages have been consistent about getting vaccinated, staying masked-up, frequent hand washing, and maintaining physical distancing. It would be great if they can include positive messages like going for brisk walks.”

– Dr. Deborah R. Young

Dr. Merrill pointed out that although there were a lot of unknowns during the initial lockdown about what constituted risky behavior, many studies have shown that being outdoors is not as risky as experts once thought.

“I think keeping public health decisions away from political battles and focusing on the science, the data, including this new information that we’ve learned, can help minimize the negative impacts of the decisions that are made,” he said.

He continued:

“[M]aking good use of the data and sharing information about what’s been learned can help decrease anxiety and prevent the imposition of unnecessary restrictions that don’t actually increase our safety and health but do significant harm. Hopefully, we can consider this a lesson learned and do better [in the future].”