Antipsychotic drugs double stroke risk: study

LONDON (Reuters) - People taking antipsychotic drugs are nearly twice as likely to have a stroke compared to those not on the treatment, British researchers reported on Friday.

The risk is even higher -- about 3.5 times -- for men and women with dementia, which means doctors should only prescribe such medicine to these patients as a last resort, the researchers said.

Previously, stroke risk associated with older antipsychotic drugs was unclear but the study published in the British Medical Journal showed both old and new treatments carry increased risk.

"The risks associated with antipsychotic use in patients with dementia generally outweigh the potential benefits, and in this patient group, use of antipsychotic drugs should be avoided whenever possible," Ian Douglas and colleagues at the London School of Hygiene and Tropical Medicine wrote."

The researchers looked at the medical records of nearly 7,000 men and women and recorded the incidence of stroke among those who at some point had taken antipsychotic drugs.

They found that they were 1.7 times more likely to have a stroke and that the risk was much higher if people had dementia.

The most common older treatments included a drug class called phenothiazine and the generic medicines haloperidol and benperidol. The most widely used newer drug in the study was Johnson & Johnson's Risperdal, known generically as risperidone, the researchers said.

Other newer drugs in the study included Eli Lilly and Co's Zyprexa, or olanzapine, Sanofi-Aventis' Solian, or amisulpride and AstraZeneca Plc's Seroquel, known generically as quetiapine.

The researchers did not look at why people with dementia are at greater risk but one possibility may be that vascular causes of certain types of dementia may be involved, said Douglas, an epidemiologist.

"We don't know why this extra risk associated with antipsychotics is even greater in people with dementia," he said in a telephone interview.

(Reporting by Michael Kahn; editing by Dina Kyriakidou)