Health experts have called for an immediate end to over-prescribing of anti-psychotic drugs after they were shown in some cases to double the risk of death among Alzheimer's patients.
The powerful drugs are normally given to people with serious mental illnesses such as schizophrenia, but are also often given to elderly people with Alzheimer's to prevent disturbing and troublesome symptoms.
Using the medications to treat the most common form of dementia is controversial, with studies having shown that the practice is associated with a range of serious adverse conditions, including Parkinson's-like symptoms, accelerated mental decline, and strokes.
The new research, which is the first to look at the effect of giving antipsychotics to Alzheimer's sufferers over long periods of time, showed that over two years survival rates fell by 35%, and after three years the risk of death almost doubled.
Rebecca Wood, Chief Executive of the Alzheimer's Research Trust, which funded the study, said: "The findings of this research are a real wake-up call and underline the danger of prescribing anti-psychotics long-term for anything other than exceptional circumstances.
"We must avoid the use of these drugs as a potentially dangerous 'chemical cosh' to patients who would be better off without it."