Common antidepressant may protect against dementia

Washington: A commonly used antidepressant medication can also provide protection against compounds that can cause memory loss and dementia, researchers including one of Indian-origin have found. Researchers at the Loyola University in Chicago found that blood levels of two neurotoxic compounds dropped significantly in depressed patients after they were treated with the antidepressant escitalopram.

The study provides new insights into how the immune system responds to depression. Stress and depression interact in a vicious cycle. Stress can lead to depression in susceptible individuals. In turn, depression, if not treated, causes stress. This stimulates the body's immune system to fight stress and depression, as it would a disease or infection. Revving up the immune system, which includes the inflammatory response, initially protects against stress. But over time, chronic inflammation can cause a range of health problems.

"In this vicious cycle, depression can trigger an inflammatory response, which in turn can exacerbate depression. It behoves us to diagnose depression early, treat it vigorously to achieve remission and work to prevent its relapse," said Angelos Halaris, professor at Loyola University who led the study. The study compared 30 severely depressed patients with 27 healthy subjects. The patients were treated with escitalopram and followed for 12 weeks. Some patients dropped out of the study due to side effects of escitalopram or other reasons.

Of the 20 patients who completed the entire study, 80

per cent reported complete or partial relief from their depression, said researchers including Vidushi Savant from Loyola University. To examine the inflammatory response, researchers measured blood levels of nine substances secreted by the

immune system. At the beginning of the study, average levels of all nine of these substances were higher in the depressed patients than in the healthy subjects. The differences were statistically significant with four of these substances (hsCRP, TNFa, IL6 and MCP1).

The inflammatory response can lead to the production of neurotoxic compounds that can kill brain cells, leading to memory loss and dementia if the depression goes untreated or fails to respond adequately to treatment. The study found that among patients treated with escitalopram, levels of two neurotoxic compounds dropped significantly. Levels of 3-hydroxykynurenine fell by more than two-thirds between week 8 and week 12. Levels of quinolinic acid dropped 50 per cent during the first eight weeks and were lower at the end of the study than at the beginning.

Escitalopram belongs to a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs). The findings were published in the Journal of Psychiatric Research.