Medicines, such as treatments for depression and allergies, have been linked to an increased risk of developing dementia, a study published in the JAMA has found.
The study, carried out by researchers from the University of Washington, in the US, evaluated 3434 patients aged 65 or over who had not displayed any symptoms of dementia. The participants were followed for an average of 7.3 years, and were given tests on memory and critical thinking at two-year intervals. The researchers also measured the participants' use of medicines with an anticholinergic effect – drugs that block a chemical called acetylcholine, which boosts nerve cell function.
The study found that 797 of the participants developed dementia over the course of the study. Of these, 79.9 per cent developed Alzheimer's disease. The researchers concluded that regular use of drugs with an anticholinergic were more likely to develop the conditions.
Dr Simon Ridley, head of research at Alzheimer's Research UK, said: 'This large study adds to some existing evidence linking anticholinergic drugs to a small increased risk of dementia, but the results do not tell us that these drugs cause the condition.'
Some of the treatments identified in the study are intended to have an anticholinergic effect, such as those designed to treat muscle spasms. However, others, particularly antihistamines and antidepressants, are anticholinergic as a side effect.
Dr Ridley added: 'Continued research to shed light on these links will be important for helping understand the benefits and potential risks of these drugs. Investment in research is vital if we are to find more effective ways of treating and preventing dementia.' The authors of the study, commented that 'efforts to increase awareness among health care professionals and older adults about this potential medication-related risk are important to minimise anticholinergic use over time.'