Exercise as it relates to Disease/Exercise vs Drugs as a Prescription for Depression

=== What is depression? === Depression is a common mental disorder that can either be long lasting or recurrent. It has the ability to substantially impair a person's ability to cope with things such as school, work, and daily life. It affects how you feel, think and behave and can be a precursor to a variety of emotional and physical problems. In its most severe form, depression can lead to suicide. The disease itself results from abnormalities in the interactions between hormones and neurotransmitters in the brain, and also irregularities in the brain's neuron connections. Saying this, neurologists are still trying to fully understand depression as it is such a complex illness. Unlike other neurologic diseases, such as Parkinson disease, which tend to affect an identified region of the brain, depression seems to affect multiple areas of the brain including the prefrontal cortex, amygdala, hippocampus, and thalamus.

Causes of depression
Studies suggest that around 40-50% of the risk of developing depression has a genetic origin. This indicates that depression is a highly heritable mental illness, and that genetics play a major role in an individual's vulnerability to depression. Other, non-genetic factors causing depression include; stress and emotional trauma, viruses (e.g., Borna virus), drug and alcohol abuse, and even stochastic (or random) processes during brain development have been implicated in the aetiology of depression.

Signs and symptoms
Depression is characterised by a variety of mental and also physical signs and symptoms that vary from person to person. The signs and symptoms one depressed individual may experience can be completely different to what another person with depression may experience. They include:

Prevalence
Depression is more common than many people would believe, one in seven Australians will experience depression in their lifetime. It ranks third highest in terms of disease burden in Australia (13.3%), and is also third highest globally. Depression is also the greatest cause of non-fatal disability in Australia (24%).

Drugs as a Prescription
Pharmaceutical drugs have long been thought of as the gold standard method of treating depression. Australia is the second-highest prescriber of antidepressant medications, 89 out of every 1000 Australians are on some form of daily antidepressant. Antidepressants act by restoring the chemical imbalances in the brain that are present in individuals with depression. Over a thousand randomised trials have been conducted globally. Statistically significant benefits have been repeatedly demonstrated and the medical literature is flooded with several hundreds of "positive" trials. That being said, the effectiveness of antidepressants between patients can vary greatly, and the greatest effect is usually exhibited on individuals with severe depression. The dosage and the type of antidepressant can also vary its effectiveness between people. Some health professionals even believe that efficacy of antidepressants simply reflects the placebo effect.

Exercise as a Prescription
The effectiveness of exercise as a prescription for depression has only recently been studied (in relation to the studies conducted on antidepressants), but the results have been promising. A 2001 study published in the American Journal of Preventative Medicine concluded that aerobic exercise at a dose consistent with public health recommendations is an effective treatment for depression of mild to moderate severity. After 12 weeks of a public health recommended dose (PHD) of aerobic exercise, mean Hamilton Rating Scale for Depression scores at 12 weeks were reduced 47% from the baseline. The response and remission rates in the PHD group are comparable to other depression treatments, such as antidepressant medication. However, it is important to realise that more detailed research into this area is needed before an accurate conclusion can be reached about the efficacy of exercise as a prescription for people who are depressed.

Recommendations
Studies and research conducted up until this point indicate that antidepressant medications and aerobic exercise are both effective ways of treating depression. Pharmacological treatments have long been thought of as the gold standard, and for good reason. But there is becoming greater evidence for prescribing exercise to combat depression as it can also help reduce co-morbidities, and it has the added benefit of not producing any side-effects. Minimal research has been conducted on the efficacy of a joint antidepressant/aerobic exercise regime to combat depression in humans, but animal studies suggest that combining the two treatments magnifies their ability to repair the chemical imbalances in the brain. In any case, aerobic exercise combined with an anti-depressant will not produce any adverse health risks and is worth undertaking. The level of aerobic exercise that will have a significant effect on depression is nothing more than the minimum requirement to maintain health. That is:

150 – 300 minutes of moderate intensity physical activity per week.

This level of physical activity will have favourable effects on not only mental, but also physical health.