Combined exercise and focused-attention meditation in people with major depressive disorder.
Major depressive disorder (MDD) is a highly prevalent and debilitating disorder, with a significant health burden. Whilst the most common and accepted first line treatment of MDD involves psychotropic medications, including anti-depressant medications such as selective-serotonin reuptake inhibitors (SSRIs), aerobic exercise and focused-attention (FA) meditation alone are also recognised to reduce symptoms of depression.
The neurogenesis hypothesis of depression proposes that depression is accompanied by a loss of new granule neurons, and that renewal of the same cells can reverse depression symptomatology. Whilst antidepressant-related interventions are known to increase neurogenesis, aerobic exercise can also increase the neurons produced in the hypothalamus. Importantly, it is understood that the new neurons that develop are not necessarily permanent and often die before differentiating into mature neurons. Certain stimuli may 'rescue' the new neurons from death, including effortful learning experiences and mental training. Based on the neurogenesis hypothesis and the data available suggesting that aerobic exercise increases the production of new neurons in the brain and that effortful mental training experiences may help prevent neuron death, the authors developed a novel neurobehavioral intervention, mental and physical (MAP) training, which was tested for its combined efficacy in improving symptoms of depression and rumination in individuals with MDD.
Men and women meeting the diagnostic criteria of the DSM-IV for non-psychotic MDD were recruited and included in the study. Exclusion criteria included bipolar or psychotic disorders, self-injurious or suicidal behaviour, history of neurological disorders, or head injury resulting in loss of consciousness. Healthy participants who did not meet the diagnostic criteria for MDD were also recruited to act as a comparator group. Of the 69 participants (33 depressed, 39 non-depressed) initially enrolled in the study, 22 depressed and 30 non-depressed subjects completed the 8 week MAP training intervention with complete data from baseline and post-intervention. The MAP training program incorporated aerobic exercise in conjunction with mental training, of which FA meditation was selected as the mental training component. The intervention period was for 8 weeks, with two sessions scheduled per week. Each session consisted of 30 minutes of instructed FA mediation (20 minutes sitting mediation followed by 10 minutes walking meditation) and 30 minutes of moderate-intensity aerobic exercise on either a treadmill or cycle ergometer at 50-70% VO2 peak. Depressive symptoms, ruminative thought patterns, cardiovascular fitness and physical activity, and cognitive control were all assessed at baseline and after 8 weeks of intervention.
After eight weeks of MAP training, both the MDD and non-MDD groups experienced significantly lower symptoms of depression compared with their baseline symptoms, with the decrease significantly greater in the depressed group compared to the healthy control. Both the depressed group and the healthy comparison groups demonstrated a significant decrease in ruminative thought patterns from pre-to-post intervention, with no significant difference between groups observed. No significant changes were observed for cardiovascular fitness or the physical activity assessment. For cognitive control, behavioural and event-related potential indices were collected during a modified flanker task. Authors reported that following MAP training, the N2 and P3 component amplitudes increased relative to baseline, particularly in the MDD group, indicating enhanced neural responses during the detection and resolution of conflicting stimuli.
The study provides good initial results for the use of MAP training as a potential intervention in patients with MDD, and whilst previous studies have demonstrated beneficial effect of aerobic exercise and meditation training in this population, no prior studies had assessed the combination of the two. A criticism of the study is that it was not compared to aerobic exercise alone or meditation alone in order to see whether the effects are significantly greater when combining the two in MAP training. Also, investigating and assessing the effect of these interventions as an adjunct to traditional pharmacological-based therapies will provide clinically useful information. Future studies with larger sample sizes should help address this issue. The study, however, provides further supportive evidence for the potential use of aerobic exercise and meditation-based intervention in individuals with major depressive disorder; however, a better understanding of the nature of this effect is required.
These abstracts are brief summaries of articles which have appeared in recent issues of herbal medicine journals, some of which may be held in the NHAA library.
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|Publication:||Australian Journal of Herbal Medicine|
|Date:||Jun 1, 2016|
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