London, Oct 11 (IANS): Some commonly prescribed blood pressure medications may increase risk of mood disorders such as depression or bipolar disorder, say researchers including one of Indian-origin.

"Mental health is under-recognized in hypertension clinical practice, and the possible impact of antihypertensive drugs on mental health is an area that physicians should be aware of and consider if the treatment of high blood pressure is having a negative impact on their patient's mental health," said Sandosh Padmanabhan, Professor at University of Glasgow in Britain.

In this study, researchers compared four common classes of antihypertensive drugs and risk of mood disorders.

They collected data on 525,046 patients (ages 40-80) from two large secondary care Scottish hospitals. 

The researchers selected 144,066 patients being treated for hypertension with either angiotensin antagonists, beta blocker, calcium channel blockers or thiazide diuretics. 

They were compared to a group of 111,936 patients not taking any of those drugs.

Researchers followed the patients for five years documenting hospitalisation for mood disorders, such as depression or bipolar disorder. 

After more than 90 days on the antihypertensive medications, the study published in the American Heart Association's journal Hypertension, found that there were 299 hospital admissions, predominantly due to major depression, among the patients studied, at an average 2.3 years after patients began antihypertensive treatment.

Patients on beta-blockers and calcium antagonists were at two-fold increased risk of hospital admission for mood disorder, compared to patients on angiotensin antagonists.

Patients on angiotensin antagonists had the lowest risk for hospitalisation with mood disorders compared to patients on other blood pressure meds and patients on no antihypertensive therapy.

Patients taking thiazide diuretics showed the same risk for mood disorders compared to patients taking no antihypertensive drugs, the study found.