Regular intake of coffee or caffeine by patients with Alzheimer's disease may worsen their neuropsychiatric symptoms, including anxiety, say researchers.

While it is well known that memory problems are the hallmarks of Alzheimer's disease, this dementia is also characterised by neuropsychiatric symptoms, which may be strongly present already in the first stages of the disorder. These are known as Behavioural and Psychological Symptoms of Dementia (BPSD) and include anxiety, apathy, depression, hallucinations, paranoid, sundowning and more. The results indicate that caffeine worsened these symptoms in mice with Alzheimer's.

The researchers also discovered significant effects, especially in relation to neophobia -- a fear of everything new -- anxiety-related behaviours, and emotional and cognitive flexibility. "The mice develop Alzheimer's disease in a very close manner to the human patients with early-onset form of the disease," said lead author Raquel Baeta-Corral from the Autonomous University of Barcelona in Spain. "They not only exhibit the typical cognitive problems but also a number of Behavioural and Psychological Symptoms of Dementia (BPSD)-like symptoms, so it is a valuable model to address whether the benefits of caffeine will be able to compensate its putative negative effects."

For the study, the team analysed the effect of caffeine on normal ageing mice and familial Alzheimers models. However, coffee has also been suggested as a strategy to prevent dementia, both in patients with Alzheimer's disease and in normal ageing processes, due to its action in blocking molecules - adenosine receptors - which may cause dysfunctions and diseases in old age. But "our observations of adverse caffeine effects in an Alzheimer's disease model together with previous clinical observations suggest that an exacerbation of BPSD-like symptoms may partly interfere with the beneficial cognitive effects of caffeine", the researchers said.