Biomarkers in psychiatry

Biomarkers are characteristic biological features that can be objectively measured and indicate either normal or diseased processes in the body. Dopaminergic system plays a pivotal role in multidimensional brain functions, such as control and modulation of movement, cognition, memory as well as motivation and emotional behaviour. Reduced glucose utilisation activity in the frontal lobe, altered utilisation activities with tasks, and a reversal of subcortical/cortical relationships have been observed in schizophrenic patients. Any stressful experience (prenatal or maternal traumatic stress or childhood trauma), via a cascade of neurochemical events, alters the microenviromental milieu of the central nervous system, resulting in altered gene and this new gene results in permanent or structural changes which are associated with sensitisation, learning, memory and developing brain differentiation. Brain-derived neurotrophic factor, produced by neurons particularly in the hippocampus and cortex, acts as a neurotrophic factor and is involved in neuroplasticity. Alanine aminotransferase is the more specific measure of alcohol-induced liver injury because it is found predominantly in the liver. Increased concentration of total and hyperphosphorylated tau protein and a reduction of amyloid β peptide Aβ42 have been reported in CSF of Alzheimer’s disease patients. Deficits in cognitive flexibility and motor inhibition may represent cognitive endophenotypes for obsessive-compulsive disorder. Low plasma vascular endothelial growth factor is associated with completed suicide. Patients with autism showed decreased activity of glutathione peroxidase in plasma and in erythrocytes compared with the controls. Accurate biomarkers, along with more reliable and valid disease criteria, will help psychiatry achieve greater objectivity in diagnosis.