Trial Investigating the Effect of Different Exercise Forms on Depression
Trial Investigating the Effect of Different Exercise Forms on Depression
During one year, 5-8% of the population will suffer from major depression. Some of the key
 symptoms are loss of interest in daily activities, loss of energy and sleeping disturbances.
 The financial consequences of this disease is estimated to be more than 30 million pounds per
 year in Great Britain and USA alone. There is an increasing interest in the effect exercise
 has on depression. Smaller studies indicate that exercise is a good treatment for depression.
 This study will be a large scale randomized trial and will hopefully bring important
 knowledge on the effects exercise has on depression.

 We will compare the effect endurance training, weight-lifting exercise and a control group
 has on depressive symptoms after 4 months training, twice a week.
Background The incidence of depression is estimated to 3-5%, with a lifetime prevalence of
 17% in western societies. The incidence in patient populations affected by chronic and
 disabling physical illnesses can be as high as 20%. Depressive symptoms as prolonged feeling
 of sadness, low self esteem and even suicidal tendencies have consequences to not only the
 patients' social life, but also shows a correlation between the severity of depression and
 number of work days lost.Depression is associated with increased risk for conditions such as
 osteoporoses, cardiovascular diseases and dementia. The global burden of disease reported by
 WHO and others stated that unipolar depressive disorders was the fourth leading cause of
 disease burden in terms of lost years of healthy life, and that major depression accounted
 for 12% of all total years lived with disability in 2000. The economic burden of depression
 on the national economy in the US was in 2000 estimated to 83,1 billion dollars (31% were
 direct medical costs, 7% were suicide-related mortality costs and 62% were workplace costs).

 In 2001 a meta-analysis of randomized controlled trials comparing exercise with other
 established treatments for patients diagnosed with depression concluded:" The effectiveness
 of exercise in reducing symptoms of depression cannot be determined because of a lack of good
 quality research on clinical populations with adequate follow up". The authors found that the
 majority of studies did not have blinded outcome assessment, nor were they based on the
 intent-to-treat principle and most had a short follow-up. In conclusion a summary of the
 latest reviews on the subject, states that it is likely that exercise has an effect in
 patients diagnosed with depression, but many of the conducted studies have significant
 methodological problems, which might have a substantial effect on trial results.Despite the
 above criticism there have been published trials suggesting that exercise has a positive
 effect in patients diagnosed with depression. A RCT (n=156, age >50, Hamilton rating scale
 for depression (HAMD)-17mean= 18,5) from 1999 compares an aerobic exercise program, standard
 medical treatment (SSRI) and a group receiving both. No significant difference was observed
 between the groups after 16 weeks of intervention.

 A study from 2004 showed an effect of aerobic exercise on depression in light to moderately
 depressed patients (n=82) not receiving medication. The study compared an exercise program of
 17,5 kcal/kg/week (jogging one mile approximately equals 100 kcal) with exercise program of
 7,5 kcal/kg/week with a control group. After 12 weeks of intervention the group receiving the
 most strenuous (17,5 kcal/kg/week) program showed a significant reduction in symptoms
 compared to the group only doing aerobic exercise similar to 7,5 kcal/kg/week and the control
 group. No significant difference was observed between the low energy expenditure program and
 the control group. A recently published study in elderly doing progressive resistance
 training supports these findings on intensity related effect of exercise on depression.The
 effect of exercise on endorphin, monoamine levels and neutrophin have been proposed as
 biological mediators of exercise on depression, as well as psychosocial mechanisms such as an
 increase of physical self-worth and distraction.

 Only one previous study have compared aerobic and non-aerobic exercise forms, which
 theoretically could be working by different biological mechanisms, such as enhanced
 serotonergic activity due to enhanced free tryptophan levels in aerobic exercise. This study
 gives us an opportunity to compare the aerobic with non-aerobic exercise in comparable
 populations.

 Studies like this rarely includes measures of biological parameters. Disturbances in the
 hypothalamic-pituitary axis with high cortisol levels and the lacking ability to suppress
 endogen cortisol in response to dexamethasone has long been known to accompany depression.
 Increased fitness has in experimental models shown to decrease cortisol response to
 psychological and physical stress. Furthermore, serum prolactin has been used as an indicator
 of central serotonergic activity which has shown an abnormal response to physical activity in
 depressed patients.

 New evidence for the biological effect of exercise includes the increase of BDNF, which is
 thought to mediate the positive effect of exercise on cognition in response to physical
 activity in rodents. The deficits in cognitive function in depressed patients is widely
 recognized, and cognition has previously been shown to relate to fitness levels in older
 adults in long term physical intervention. The effect of long term physical intervention on
 cognitive skills, have to our knowledge never been examined in clinically depressed patients.

 On this background we argue that a randomized study based on the intent-to-treat principle,
 including clinical populations and with a long follow-up is needed to evaluate the efficacy
 of exercise in patients diagnosed with light to moderate depression, regarding depressive
 symptoms and lost days from work.
Inclusion Criteria:

 -  Age: 18-55

 -  ICD-10 diagnoses F32.0, F32.1, F33.0, F33.1

 -  Speak fluent danish

 Exclusion Criteria:

 -  Not able to do exercise

 -  Drug/alcohol addict

 -  The patient already engages in more than one hour of weekly exercise.

 -  The patient has not been working the last 24 months due to depression.

 -  Suicidal behavior.