All drugs used to treat psychosis are linked to an increased risk of stroke, and dementia sufferers are at double the risk, according to a study published on the British Medical Journal website.
Previous research has shown that second generation (atypical) antipsychotic drugs can increase the chances of patients having a stroke. But the risk of stroke associated with first generation (typical) antipsychotics, and whether the risk differs in people with and without dementia, is not known.
Concerns about an increased risk of stroke among people taking atypical antipsychotic drugs were first raised in 2002, particularly in people with dementia. In 2004, the UK's Committee on Safety of Medicines recommended that these drugs should not be used in people with dementia, despite a lack of clear evidence.
A team of researchers from the London School of Hygiene and Tropical Medicine, examined data from the General Practice Research Database (GPRD), which contains the clinical information of more than six million patients registered at over 400 general practices in the UK.
They assessed the effect of exposure to antipsychotic medication on the incidence of stroke in 6 790 patients with a recorded incident of stroke and at least one prescription of any antipsychotic between January 1988 and the end of 2002.
The authors found that during periods when patients were receiving an antispychotic drug they were 1.7 times more likely to have a stroke, whereas people with dementia were 3.5 times more likely to have a stroke whilst taking any antipsychotic.
The likelihood of having a stroke was slightly higher for people taking atypical antipsychotics than people taking typical antipsychotics.
The study did not look at the specific mechanisms linking antipsychotics and stroke or why the risk is greater with atypical antipsycotics.
Previously, the risk of stroke associated with typical antipsychotics was unclear, say the researchers, but "we have established that all types of antipsychotics carry an increased risk, although the risk might be somewhat higher with the atypical drugs."
They conclude: "We reaffirm that 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 wherever possible."
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