New research shows that patients on anti-depressants are more likely to experience improvement if they believe in a "concerned God".

The study, released on Tuesday by the Chicago-based Rush University Medical Center, found that patients with strong beliefs in a personal and concerned God were 75 per cent more likely to get better with medical treatment for clinical depression than other patients.

"In our study, the positive response to medication had little to do with the feeling of hope that typically accompanies spiritual belief," said Patricia Murphy, PhD, a chaplain at Rush and an assistant professor of religion, health and human values at Rush University. "It was tied specifically to the belief that a Supreme Being cared."

Results were based on responses from 136 adults diagnosed with major depression or bipolar depression at inpatient and outpatient psychiatric care facilities in Chicago. They were surveyed shortly after admission for treatment and eight weeks later.

The surveys utilised the Beck Depression Inventory, the Beck Hopelessness Scale, and the Religious Well-Being Scale – all standard instruments in the social sciences for assessing intensity, severity and depth of disease and feelings of hopelessness and spiritual satisfaction.

The new study from Rush University took research a step further from previous studies on depression and faith that have shown that those who have a relationship with a higher power and have a higher sense of purpose were less likely to have depression than others.

Researchers tested those diagnosed with clinical depression and their response to medication, defined as a 50 per cent reduction in symptoms.

"For people diagnosed with clinical depression, medication certainly plays an important role in reducing symptoms," Murphy said in the paper, featured in Journal of Clinical Psychology.

"But when treating persons diagnosed with depression, clinicians need to be aware of the role of religion in their patients' lives. It is an important resource in planning their care."

When testing to see whether the improved response they saw in patients was instead linked to the feeling of hope – which is typically a feature of religious belief – rather than belief in a concerned God, they found that the degree of hopefulness did not predict how a patient fared on anti-depressants.