These drugs are commonly used in elderly patients to treat illnesses such as irritable bowel syndrome, urinary incontinence, and Parkinson's disease, so it is important that doctors are aware of this effect, say the researchers.
They interviewed 372 elderly people without dementia about current and past illnesses and drug use. Cognitive performance was assessed and participants were monitored for up to eight years.
About 10% of the people in the sample took anticholinergic drugs over an extended period. Drug users showed poorer cognitive performance compared with non-users and 80% met the criteria for mild cognitive impairment compared with 35% of non-users. However, drug users were not at increased risk of developing dementia.
Even after taking account of other known risk factors for cognitive impairment, anticholinergic drugs remained the most highly significant predictor of this condition, say the authors.
Given the aim of identifying mild cognitive impairment is the early treatment of dementia, people with mild cognitive impairment due to anticholinergic drugs could be in the absurd situation of receiving pro-cholinergic drugs to counteract the effects of anticholinergic agents, say the authors.
They suggest doctors assess current use of anticholinergic drugs in elderly people with mild cognitive impairment before considering treatment for dementia.