The aetiology of depression is complex. The reason for this may be that depression is caused by different things is different people. The traditional view of depression is that it s caused by a deficiency of serotonin in the brain. Modern medical treatments as a result centre on the use of selective serotonin reuptake inhibitors (SSRIs). These drugs prevent the reuptake of serotonin from the synaptic gap back to the synapse of the afferent nerve and this increases the amount of serotonin in the synaptic space. Placebo controlled studies however show that these drugs are really no more effective than placebo treatments for depression. In fact in many people SSRIs have negative effects and can increase the likelihood of suicide or the development of worsening depression. Part of the reason for this may be that serotonin deficiency is not the cause of depression in many individuals, and the fixation on drugs to increase serotonin levels has been a short-sighted exercise in barking up the wrong tree.
More recently a new class of drugs called the noradrenaline reuptake inhibitors (NRIs; sometimes called adrenergic reuptake inhibitors ARIs) have been developed. These new drugs are based on the theory that in some individuals, a deficiency of noradrenaline, adrenaline and dopamine (catecholamines) might be the cause of depression. This is in effect a tacit admission by medicine that their first attempt might not have been a good attempt. The development of NRIs is not a surprise to nutritionist who have long suspected that depression may result from a widespread imbalance in a number of neurotransmitter systems. The nutritional approach to treating depression is far more effective than the medical approach because it takes a holistic view and does not attempt to target a single neurotransmitter subgroup. Instead optimisation of all neurotransmitter groups, using a combination of high quality diets, isolated amino acid and exercise aims to produce a synergistic rebalancing within the central nervous system.
For example, exercise is perhaps the single most beneficial treatment for certain forms of mild depression. Not only is the physical activity useful, but the social aspect of performing exercise is highly underrated. The use of single amino acid treatments in nutritional therapies has centred on the use of L-tryptophan and its metabolite 5-hydroxytryptophan, as well as L-tyrosine. These amino acids are beneficial because they are used by the brain to manufacture serotonin and the the catecholamine neurotransmitters noradrenaline, adrenaline and dopamine. They are superior to drugs because they supply substrates for neurotransmitter synthesis before the rate limiting step in the synthesis pathway. In this way the brain's own natural feedback inhibition is still able to prevent excessive production of single neurotransmitter types, something which a drug treatment bypass. High quality diets improve health generally and as physical health improves mental health often concomitantly follows.