Exercise Effects on Depressive Symptoms in Cancer Patients

Today we are discussing the benefits that exercise can bring for cancer patients by mitigating depression and anxiety with Gwendolyn Thomas, an exercise physiologist who focuses on exercise prescription in managing various diseases and Maggie Bedillion, a graduate student in Thomas's lab who is studying these issues. Professor Thomas is an assistant professor at Syracuse University in New York and is the director of the Exercise Prescription Lab at the university.

Cancer Network: Many cancer patients have symptoms of depression and anxiety following their diagnosis. What do we know about how different forms of exercise can help patients with these symptoms?

Maggie Bedillion: The past 20 years of research have shown that resistance and aerobic exercise have beneficial effects on symptoms of depression. The multi-faceted nature and complex etiology of depression makes the benefits of exercise especially notable, if you think about its ability to improve mood and overall quality of life, pain, and insomnia in these patients.

Dr. Thomas:  As Maggie just said, aerobic exercise and resistance exercise are the two forms of exercise and the benefits of aerobic exercise for depressive symptoms have been really well established. Most studies find that 3 times per week of aerobic exercise at a moderate intensity for a minimum of 9 weeks helps to treat depression.

Research supports that exercise is an evidence-based treatment for the management of depression. However, it is important to keep in mind that moderate and vigorous intensity exercises were shown to be more effective than lighter intensity exercises. Fewer studies have examined the effects of resistance exercises on depression. However, in a recent meta-analysis by

Brett R. Gordon and colleagues published in JAMA Psychiatry, they examined 33 clinical trials and found that resistance exercise was associated with improvement in depressive symptoms such as low mood, a loss of interest in activities, and feelings of worthlessness.

What's really interesting about what they found is that these beneficial effects of resistance exercise occurred regardless of a person’s health status, age, and sex.

What is important to note in these findings is that these effects occurred regardless of the total prescribed volume of resistance exercise or seen changes in strength. In addition, this analysis found that resistance exercise sessions that were less than 45 minutes are effective and resistance exercise may be particularly helpful for reducing symptoms in people who have more severe depressive symptoms.

Cancer Network: Research has shown a link between cognitive impairment and depression among breast cancer and other cancer patients, especially those who have received chemotherapy. Can you talk about this link between cognitive impairment and depression?

Dr. Thomas:  There is a link between cognitive impairment and depression. Although the nature of the associations remain unclear, both subjective or the patient’s self-report that he or she is experiencing cognitive impairment and objective cognitive impairment, or the measurement of changes in cognitive function on specific neurological tests, have been found to be associated with depression.

A recent study found that pre-cancer pre-treatment worry was associated with subjective and objective measures of cognitive impairment. The study also found that depression in individuals receiving chemotherapy is related to cognitive impairment on neurophysiological tests.

It has also been shown that breast cancer patients with the most severe depressive symptoms are those who are currently experiencing the most cognitive impairment. So, what that suggests is that it is important to understand how and for whom depression plays a role in cognitive functioning in breast cancer survivors.

Maggie Bedillion: Building off of what Gwendolyn said, a study from 2014 found moderate cognitive deficits in executive functioning, memory, and attention in individuals with depression. These cognitive impairments were associated with poor social functioning. This is really important if we think about the impact on breast cancer survivors’ daily life because about one-third of breast cancer survivors will report experiencing psychological distress.

A cancer diagnosis and chemotherapy can negatively a woman’s ability to perform activities of daily living. That is why it is so important to examine subjective cognitive impairment, because self-reported complaints can reflect a woman’s awareness of deficits in cognition and more closely relate to the disruption that cancer and cancer treatment have on a survivor’s everyday life.

Cancer Network: You and your colleagues recently did a study on the role of physical activity mitigating cognitive impairment and depression among breast cancer survivors. Can you talk about that study and what you found?

Maggie Bedillion: Our study sought to expand on prior research findings that different breast cancer treatments may increase depression and cognitive deficits. We know that depression can induce problems in cognition. We also know that physical activity can improve both depression and cognition. Our study examined whether depression symptoms mediate or help explain the effects of breast cancer treatment on cognitive difficulties. We also examined whether physical activity may help to mitigate these effects.

What we found was that regardless of treatment type, depressive symptoms in breast cancer survivors play a role in cognitive difficulties. This is particularly important to keep in mind because the diagnosis itself and going through breast cancer treatment can be a stressful time and any increase in depression may lead to further cognitive difficulties.

We also found that chemotherapy, tamoxifen and anastrozole, all negatively affected cognition. But these effects varied depending on the amount of moderate or vigorous physical activity that a woman engaged in. For example, both moderate and vigorous activity mitigated chemotherapy’s direct effects on cognition. This supports efforts by clinicians and researchers to look at the beneficial effects of more intense exercise in breast cancer survivors.

When I say intense exercise, that doesn’t mean an individual needs to go out and run a marathon. Some examples of moderate and vigorous exercise can be walking, running, biking, or swimming.  If we monitor patients for even small changes in depression and cognition following treatment, this may help identify those who are in need of targeted intervention such as exercise. Encouraging breast cancer survivors to engage in exercise on a regular basis is one of the best behavioral strategies we can offer to help improve their outcomes.

Cancer Network: Clinicians do not always discuss the benefits of exercise for their cancer patients’ well being. What is your advice for how they can discuss the potential benefits of exercise to their patients and what are some study results they can cite?

Dr. Thomas: That is absolutely correct and based on conversations I have had with clinicians, it seems that there are several things that contribute to this oversight. If clinicians do give advice, they tend to base this advice on the current American College of Sports Medicine guidelines. What those guidelines suggest is that 150 minutes of aerobic exercise and two resistance exercise sessions per week are beneficial. These guidelines are for general health. But for someone who has never exercised, that can be really daunting. Or if someone is experiencing adverse symptoms, that could prevent them from doing long stretches of activity. If you take a look at 150 minutes, you think ‘I have to do this for a long period of time.' So, as exercise physiologists, we tend not to do a good job of communicating that exercise has been shown to be very effective in small bouts and can be personalized to target individual’s symptoms.

In fact, a recent study in Medicine & Science in Sports & Exercise, demonstrated that completing as little as three resistance exercise sessions per week of 13 minutes apiece can increase strength. Why that is important is that strength can in turn help individuals gain mobility and functioning and those are really important components of quality of life.

Making exercise more manageable and approachable is the key to helping people consistently engage in exercise and it is important to support them to make this a daily part of their life. Additionally, individualizing exercise prescriptions is a huge focus of research right now and it should be a focus of those working with breast cancer survivors. Not everyone experiences the same symptoms or side effects and they also don't have the same barriers to exercise.  Understanding these differences and using those individualized prescriptions is a big focus of what we do in our lab.

Cancer Network: Thank you so much to both of you for joining us.

Dr. Thomas: Thank you.

Maggie Bedillion: Thank you.