Earlier published studies had revealed that the drugs increased the risk of stroke and heart problems; yet, despite this downside, they were still considered to be far safer than conventional antipsychotics.
The newly found suppressed trials revealed that the four drugs were associated with 276 deaths for every 1000 elderly patients with dementia, which would suggest that they could be far more dangerous than the previous generation. The drugs had been taken for only up to three months before the patients had died.
The studies were carried out as far back as two years ago, and the USC researchers say they can find no good reason why they have never been published. All had used the scientific 'gold standard' of randomised, double-blind trials, where the patient did not know if he was being given a drug or a placebo. However, all but one had been sponsored by one of the drug companies that manufacture the drugs being studied (JAMA, 2005; 294: 1934-43).