Depression and exercise

Major depressive disorder and other forms of depression or even some of the depression symptoms are the most prevalent psychiatric disorders in the world, with ersoal, individual and other costs. About 20% of Americans will experience an episode of depression(length: 6 months- years) during their lifetime.

Researchers have found the positive effects of exercise. Physical activity have been proposed as a protective activity not only for the coronary or somatic diseases but for the stress related mood disorders, from anxiety disorders(phobias, obsessive compulsive disorder, post-traumatic stress disorder) to the spectrum of depression(bipolar, unipolar, major or mild).

Is not only that exercise is preventive, but clinically diagnosed patients show clinical improvements even greater thatn with more traditional therapy. Well let’s think about. In evolutionary terms, poor body is designed to have a balance in the metabolism between physical activity (used for getting food, fighting with animals, protecting from danger, mating or just for basic metabolic mainteneance) and energy intake(food, nutrients, water). The brain of any hominid primate is designed for some extend of physical acitivy at some intensity, and limite caloric intake. The dynamic of our society creates some situation where an overeating of sugar, complex carbohydrates, hight fat and junk food, with sedentary lifestyle is completely promoted and accepted. This situation, clearly explains some of the mental health epidemics we are living in North America.

In animal models as well, particulary with laboratory rats, when they are exposed to an environment(for example wunning into a wheel) protects the rats toward stress or consequences of umpredictable stressors, compared with rat who didn’t have access to exercise. Some researchers believe the animal modles results implies that in future researchers it can be shown how exercise can help reversing the effects of depression disorders. The positive outcome for any treatment of depression is determined by three or four factors such as clinical impression, remission of the symptoms, effects of the treatment or medication, specific tests.

Treatment studies using both unselected and clinical samples have found that engaging in prescribed structured exercise significantly reduces levels of depressive symptoms (for meta-analyses see Conn, 2010; Lawlor & Hopker, 2001; Mead et al., 2009). Indeed, effect sizes comparing intervention and control groups in these meta-analyses were 0.37 in the unselected samples and ranged from 0.82 to 1.1 in the clinical samples, making the effects of exercise comparable to those obtained with cognitive therapy.

Although these are large effect sizes, the authors of these meta-analyses noted that methodological difficulties, such as lack of adequate concealment of randomization, lack of blinding, and lack of follow-up assessments beyond the intervention period, make it difficult to determine the true effect size of exercise treatment on reducing depressive symptoms. Moreover, in many of the studies the criterion for “improvement” or “positive outcome” is not clearly specified. For example, several investigations used total scores on the Beck Depression Inventory − II (BDI; Beck, Steer, & Brown, 1996; Steer, Ball, Ranieri, & Beck, 1999) to assess the effects of the intervention on depressive symptoms. It is not clear from a single total score, however, which aspects of depressive symptomatology (e.g., positive or negative affect) are changing in response to exercise or physical activity.

Finally, the large majority of these studies examined the effects of prescribed or supervised exercise, raising the question of whether these results are generalizable to individuals without access to personal exercise prescription or supervision.