Antipsychotic drugs given to Alzheimer’s patients may be contributing to early death, according to a new study.

While so-called neuroleptic drugs or sedative medications were originally developed for schizophrenia, they are sometimes used on an “off-label” basis to calm difficult or aggressive dementia patients. But British researchers contend these drugs may actually be causing patients to die.

Alzheimer’s sufferers who were given the antipsychotic medications died an average of six months earlier than those given a placebo, according to researchers led by Professor Clive Ballard of King’s College London. The five-year study also found that the neuroleptic drugs were associated with a significant deterioration in verbal fluency and cognitive function.

The issue notably flared to light in December, when a New York Times report said that Eli Lilly, the maker of Zyprexa, a drug for schizophrenia and bipolar disorder, was promoting the off-label use of the drug in older patients with symptoms of dementia. The company denied the report.