ISLAMABAD: Depression has been shown to alter the structure of the brain's white matter, which contains the circuitry that allows brain cells to communicate with each other, and which underpins brain function.

The researchers describe how they found that white matter integrity - that is, a measure of the quality of the brain's white matter - was reduced in participants who reported symptoms of depression, compared with unaffected participants. They suggest that the findings should help us to better understand the biology of depression and improve its diagnosis and treatment.

Depression is not the same as the mood changes and short-lived emotional reactions that we have to everyday challenges. It is a common illness that can endure, cause great suffering, and damage people's lives at school, at work, and at home. As imaging technologies advance, scientists are discovering more and more about the role of white matter and how its alteration might affect normal brain function and contribute to psychological disorders.

DTI is a type of MRI that is showing promise as a way to characterize tiny changes in brain structure to track disease progression and treatment. DTI creates a 3-D map as it follows the diffusion of water in brain tissue. The DTI results showed that the participants with depression had reduced white matter integrity when compared with the participants without depression. This reduction was seen globally as well as in certain "tracts," or bundles of axons, namely "in two of the three categories of tracts," and also "in individual tracts."

Researcher Dr. Heather Whalley, senior research fellow in the Division of Psychiatry at the University of Edinburgh, says that their study uses "data from the largest single sample published to date and shows that people with depression have changes in the white matter wiring of their brain. A study with such a large sample would suggest that the findings are likely to be regarded as very robust. This is supported by meta-analyses that have pooled data from previous studies that have found links between depression and "reduced white matter integrity in several brain regions." However, the researchers note that a limitation of their study is the fact that the participants were screened for depression based on self-reported symptoms and not in an interview using formal criteria.