New Delhi: The duration of depression may influence the severity of changes in brain function associated with the mental health disorder, according to a new study.

Researchers from the University of Sao Paulo and the University of Oxford analysed brain images of 46 patients diagnosed with major depression and found distinct patterns of brain connectivity linked to how long a person had been depressed.

The findings, published in the journal Scientific Reports, suggest that chronic depression may alter communication between key brain networks differently from shorter-term depressive episodes.

The study focused on two major brain networks -- the central executive network (CEN), associated with executive control and goal-oriented tasks, and the default mode network (DMN), linked to introspective thoughts and self-reflection.

Lead author Tamires Zanao said patients with depression lasting more than 24 months showed different connectivity patterns compared with those experiencing more recent depressive episodes.

Researchers found that among patients with shorter episodes, connectivity between the CEN and parts of the DMN weakened as symptoms became more severe. However, among those with long-term depression, greater symptom severity was associated with stronger connectivity between the two networks.

The researchers said disrupted coordination between these networks may contribute to symptoms such as rumination, negative self-focused thoughts and difficulty concentrating.

The study also suggested that changes in brain connectivity linked to depression may evolve over time, with different patterns emerging in prolonged or recurrent cases.

The researchers said the findings could help in the future development of more personalised treatments for depression.