Physical activity and light to moderate drinking (as is often associated with the Mediterranean diet) are recommended as ways to reduce risk for heart disease and type 2 diabetes. New research shows that among healthy people, symptoms of depression can counteract the anti-inflammatory benefits of both exercise and light to moderate alcohol consumption.
C-reactive protein (CRP) is a cardiometabolic risk marker. High measures of CRP are a sign of inflammation. Leisure-time physical activity and light to moderate alcohol intake (defined as about half a drink per day for women and one drink per day for men) are associated with lower levels of CRP. Depression is associated with higher levels.
A study by Edward C. Suarez et al. published recently in the journal Brain, Behavior, and Immunity examined 222 nonsmoking men and women aged 18-65 years. These participants were physically healthy and had no history or diagnosis of psychiatric conditions. Participants recorded the amount of alcohol they consumed and the amount of physical activity in which they participated. CRP levels in their fasting blood samples were measured, and they also completed an inventory of depressive symptoms.
Those people who were physically active had lower levels of CRP, but the 4.5% of participants with depressive symptoms did not see any anti-inflammatory benefits from physical activity. Similarly, light to moderate drinking was associated with lower levels of CRP only in men who were not depressed.
Depression did not seem to affect other markers of physical health in this study, such as levels of triglycerides or cholesterol.
Editor’s Note: This study suggests that treating depressive symptoms should be a part of any plan to reduce cardiovascular risk. It seems that depression has effects that go beyond psychological distress and may prevent patients from reaping the benefits of their healthy behaviors. The effect of depression in preventing heart healthy changes in CRP could be one of many factors mediating the high levels of cardiovascular risk in depression. People with depression are twice as likely to have a heart attack than those without depression.
Research has connected cardiovascular fitness with depression risk and treatment. A Swedish study published last year in the British Journal of Psychiatry examined records of men conscripted into the military at age 18 and compared their cardiovascular fitness at the time with hospital records from later decades. Low cardiovascular fitness at the time of conscription was associated with increased risk for serious depression.
Editor’s Note: This study provides more evidence that exercise, which increases cardiovascular fitness and decreases many of the elements of the metabolic syndrome, is good for cardiovascular and neuropsychological health, including mood stability. It is noteworthy that exercise also increases both brain-derived neurotrophic factor or BDNF (important for neural development and long-term memory) and neurogenesis (in animals), effects shared by almost all treatments with antidepressant properties. Making exercise a routine part of a regimen aimed at medical and psychiatric health is a great idea.
Many patients with depression require two or more treatments in order to achieve remission. In a 2011 study by Trivedi et al. published in the Journal of Clinical Psychiatry, patients with major depressive disorder who had not responded adequately to selective serotonin reuptake inhibitor (SSRI) antidepressants improved when an exercise regimen was added to their regular treatment.
The patients, aged 18-70 years old, were all sedentary at the start of the trial. They were randomized to one of two exercise regimens: a high dose regimen (16 kcal/kg per week, equivalent to walking at about 4 mph for 210 minutes per week) or the low dose (4 kcal/kg per week, equivalent to walking at 3 mph for about 75 minutes per week). Both groups improved significantly by the end of the study. Remission rates (adjusted for differences between groups) were 28.3% for the high dose group and 15.5% for the low dose group.
The rates of improvement with exercise were similar or better to those commonly seen with other augmenting agents such as lithium, T3, buspirone, and atypical antipsychotics, but without side effects and other inconveniences such as blood monitoring.
Other studies have indicated that exercise by itself and in combination with other treatments has efficacy in depression. Exercise can change serotonin and norepinephrine function and can increase brain-derived neurotrophic factor (BDNF), a, and neurogenesis in the hippocampus.
The researchers looked for moderating variables that may have affected the outcomes of various participants. Men, regardless of family history of mental illness, had better remission rates in the high dose group. Women without a family history of mental illness also improved more in the high dose group, while women with a family history of mental illness improved more in the low dose group, though this finding was statistically nonsignificant.
While the researchers observed that those in the high-dose group did exercise more than those in the low-dose group, participants in the high-dose group had more difficulty sticking to their exercise regimen. It may be that even though high doses of exercise offer slightly higher rates of remission, lower doses may be more effective clinically if patients can stick to the low-dose regimen better.
Patients with Bipolar Depression Have a Higher Mortality Rate, Especially if They Also Have Cardiovascular Disease
In a large longitudinal study of depressed patients in Taiwan that was published in the Journal of Psychiatric Research this year, Chang et al. found that after 10 years, patients with bipolar depression (N=1,542) had significantly higher mortality rate than those with other types of depression (N=17,480). Patients with bipolar depression were twice as likely to have died from suicide or accidental death than were patients who had other types of depression. When cardiovascular disease was also present in both groups, patients with bipolar disorder were also four times more likely to have died from suicide or accidental death than those with other types of depression.
Editor’s Note: These data again emphasize the critical importance of patients with bipolar disorder carefully looking after their medical and cardiovascular health both early on and throughout the entire course of their illness.
Much of the excess medical mortality in bipolar disorder is attributed to cardiovascular disease, and now those with cardiovascular disease also appear more prone to suicide. This should be a call to action to improve the long-term treatment of both bipolar disorder and its common comorbidity, cardiovascular disease.
Get your medical illness treated!
It will improve your health and longevity. Especially treat these signs of the metabolic syndrome, a major risk factor for cardiovascular disease:
- Cholesterol–Increase “good” cholesterol (high-density lipoproteins or HDLs) and lower “bad” cholesterol (low-density lipoproteins or LDLs)
- High Triglycerides–Triglycerides should be below 150 mg/dL
- Blood Pressure–Aim for 130/85 mmHg or lower
- Blood Sugar–Fasting blood sugar (glucose) should stay below 100 mg/dL
- Overweight & Obesity–Keep waist circumference under 40” for men or 35” for women
Exercise is good for all of these!
In a review article in the Neuroscientist published in February of this year, Kirk I. Erickson and collaborators wrote that “[m]ajor depressive disorder is considered a risk factor for Alzheimer’s dementia and memory impairment and is associated with less BDNF and greater hippocampal atrophy, possibly through a BDNF pathway. However, exercise and effective treatment for geriatric depression increases BDNF levels, increases serotonin fibers, is associated with greater hippocampal volumes, and reduces the risk for Alzheimer’s dementia.”
Editor’s note: Not a bad set of benefits from exercise! The researchers suggest that exercise is extremely important in reversing the decreases in brain-derived neurotrophic factor (BDNF) associated with depression, helping to improve depressed mood, increasing cardiovascular fitness, and maintaining healthy cognition.
Hippocampal volume and BDNF levels in blood both decrease with age. Yet exercise increases both BDNF and the formation of new neurons (neurogenesis) in animals. New data in humans suggest that aerobic fitness is associated with the size of the hippocampus, both in both children and adults. It is not clear yet whether this increase in hippocampal volume is directly driven by increases in BDNF and/or neurogenesis. However, since a smaller hippocampus is a risk factor both for depression and for mild cognitive impairment progressing to Alzheimer’s dementia, attempting to enhance hippocampal volume in any way possible is probably a good idea.
Methods of increasing hippocampal volume include treatment with antidepressants or with lithium. In the 2012 paper Erickson and collaborators also wrote, “Anaerobic exercise enhances executive and memory function and reduces hippocampal atrophy in late adulthood, and this may be partially mediated through a BDNF pathway.”
Erickson and collaborators conducted a longitudinal study published in 2010 that quantified the amount of physical activity subjects engaged in by calculating the total number of blocks walked per week. Individuals reporting greater amounts of physical activity at the beginning of the study had, upon examination nine years later, greater gray matter volume in several parts of the brain, including the hippocampus. This effect was “dose-dependent,” meaning that only those individuals who walked at least 72 blocks per week (roughly equivalent to 1 mile per day) had significant sparing of brain tissue nine years later. The study found increased gray matter volume in the prefrontal cortex and in the temporal lobe.
After a further follow-up of four more years, greater gray matter volume with physical activity was associated with a two-fold reduced risk of cognitive impairment. The researchers concluded that “physical activity patterns earlier in life were linked to brain volume and cognitive impairment later in life.”
There are a number of important points to remember about cognitive impairment. One is that increasing hippocampal volume and preventing its decrement with aging may help prevent age-related memory loss and potentially the rapidity at which mild cognitive impairment progresses. Read more
According to Heartwire, an article in the New England Journal of Medicine indicates that having any of these risk factors increases the likelihood of cardiovascular disease later in life. The more risk factors one has, the greater the increase in risk.
Across the whole meta-analysis, participants with no risk factors at age 55 (total cholesterol level: <180 mg/dL;
blood pressure: <120 mm Hg systolic and 80 mm Hg diastolic; nonsmoking; nondiabetic) had drastically better odds
of avoiding death from cardiovascular disease through the age of 80 than participants with two or more major risk
factors (4.7% vs 29.6% among men and 6.4% vs 20.5% among women).
People with an optimal risk-factor profile also had lower lifetime risks of fatal coronary heart disease or nonfatal MI (Editor’s Note: myocardial infarction, or heart attack) (3.6% vs 37.5% among men, <1% vs 18.3% among women) and fatal or nonfatal stroke (2.3% vs 8.3% among men,
5.3% vs 10.7% among women), compared with those with two or more risk factors.
What this article does not mention is that depression is a risk factor for coronary artery disease, and should be treated just as aggressively and persistently as the other cardiovascular risk factors.
Also as we’ve written before in the BNN, exercise is one element of a healthy life style that can positively affect all of these risk factors. Starting a healthy diet and exercise regimen in middle age will have long-term positive effects and reduce risks later in life.
Another article in the Telegraph today suggests that aerobic exercise can increase the size of the hippocampus in elderly people and lead to improvements in memory, attention, and ability to multi-task. Children who were more fit were also better at multitasking. Art Kramer of the Beckman Institute for Advanced Science and Technology at the University of Illinois said,
“It is aerobic exercise that is important so by starting off doing just 15 minutes a day and working up to 45 minutes to an hour of continuous working we can see some real improvements in cognition after six months to a year.
“We have been able to do a lot of neuroimaging work alongside our studies in the elderly and show that brain networks and structures also change with exercise.
We recently wrote about a study that suggested exercise may improve cognition function in depression. In today’s New York Times, an article suggests that in mice, exercise expanded the brain’s capacity to store energy, a process known as supercompensation.
While a brain with more fuel reserves is potentially a brain that can sustain and direct movement longer, it also “may be a key mechanism underlying exercise-enhanced cognitive function,” says Hideaki Soya, a professor of exercise biochemistry at the University of Tsukuba and senior author of the studies, since supercompensation occurs most strikingly in the parts of the brain that allow us better to think and to remember. As a result, Dr. Soya says, “it is tempting to suggest that increased storage and utility of brain glycogen in the cortex and hippocampus might be involved in the development” of a better, sharper brain.
Tracy L. Greer of the University of Texas Southwestern in Dallas presented an abstract at the 51st Annual Meeting of the National Institute of Mental Health’s New Clinical Drug Evaluation Unit (NCDEU) in 2011 that suggested that exercise improved the cognitive function of patients being treated with selective serotonin reuptake inhibitors (SSRIs) for major depressive disorder.
Thirty-nine participants reported cognitive impairment at baseline. Subjects were randomized to receive antidepressant treatment in the form of an SSRI augmented by either an exercise regimen designed to burn 16 kilocalorie/kg per week (kkw) or one designed to burn 4 kkw. Both exercise regimens resulted in improved response time on a measure of attention, and for the higher intensity (16 kkw) exercise group, there were improvements in response time for visual memory tasks as well as decreased errors on an executive function task.
Editor’s note: There is a somewhat mixed literature on the efficacy of exercise in potentiating antidepressant effects of other treatments. Recent data by Fred Gage and colleagues showed that in animals, exercise increased not only brain-derived neurotrophic factor (BDNF), which seems to be necessary for long-term learning and memory, but also the formation of new neurons (neurogenesis). Gage found that new neurons that migrated to the dentate gyrus of the hippocampus were more excitable than older neurons and were important in a variety of cognitive tasks.
The newer neurons could more precisely distinguish between different stimuli, while the older neurons were sufficient only for discriminating stimuli that were widely and obviously different from each other.
Thus, the increase in new neurons and BDNF that may follow exercise and antidepressant use may be associated with some cognitive improvement in depression, particularly in the realm of response speed and perhaps also in making relatively fine discriminations among relatively similar objects.
While not much evidence for the effect of exercise on cognition has been collected in humans, exercise has many other benefits. Since it is good for cardiovascular fitness and wellbeing, as well as potentially generating new neurons that could play an important role in fine cognitive discriminations, encouraging exercise in depressed patients (especially as their depression improves and they have renewed motivation to engage in exercise regimens) could be of value, even if exercise is not a guaranteed enhancer of antidepressant effects per se.