The biology of depression.

Depression is a common psychiatric disorder prevalent in 10-15% in general population. To know the biology of the disease many hypotheses have been proposed. Genetic basis for depression is provided by family studies which show higher risk of depression among first degree relatives. Abnormalities in serotonergic activity in depression can occur in one or more levels. Other neurotransmitters like gamma amino butyric acid (GABA) and dopamine are also considered to have some role in depression. Hormonal abnormalities like hypercortisolaemia are found in patients with depression. Structural and functional neuro-imaging studies in depression suggest the involvement of brain in depressive disorders.