Biological Therapies for Depression

Anti-depressants is one biological therapy for the treatment of depression. They only relieve the symptoms of depression and are taken for at least four to six months. 

As depression is thought to be caused by a deficiency of neurotransmitters such as serotonin and noradrenaline, anti-depressants are taken to either reduce the rate of re-absorption or by blocking the enzyme that breaks down the neurotransmitter. These will increase the amount of neurotransmitter that enters cells. Therefore, the symptoms of depression will decrease. 

There are two types of anti-depressants. Tricyclics block the mechanism that re-absorbs serotonin and noradrenaline into the presynaptic cell. This then causes more of these neurotransmitters to be left in the synpase meaning their activity is prolonged so the transmission of the next impulse is easier.

The second type of anti-depressant is called Selective Serotonin Re-uptake Inhibitor (SSRI's). These work in a similar way to tricyclics but instead of blocking both serotonin and noradrenaline, they only block the re-uptake of serotonin. This increases the quantity of serotonin therefore reducing the symptoms of depression. 

However, the effectiveness of anti-depressants may depend on the severity of depression. Kirsch reviewed clinical trails of SSRI anti-depressants and concluded that only in cases of…