A new research into Alzheimer's disease (AD) suggested that secondary infections and new inflammatory events amplify the brain's immune response and affect memory in mice and in humans - even when these secondary events occur outside the brain.

The study was published in Alzheimer's and Dementia, the journal of the Alzheimer's Association. Scientists believe that key brain cells (astrocytes and microglia) are already in an active state due to inflammation caused by AD and this new research shows that secondary infections can then trigger an over-the-top response in those cells, which has knock-on effects on brain rhythms and on cognition.

Colm Cunningham, Associate Professor in Trinity's School of Biochemistry and Immunology, and the Trinity Biomedical Sciences Institute led the research. He said, "Alzheimer's disease is the most common form of dementia, affecting more than 5 per cent of those over 60 and this distressing, debilitating condition causes difficulties for a huge number of people across the globe. The more we know about the disease and its progression the better chance we have of treating those living with it. We believe our work adds to this knowledge base in a few ways. Primarily, we show that the Alzheimer's-affected brain has a greater vulnerability to acute inflammatory events, even if they occur outside the brain".

Cunningham added, "Placing this within the context of the slowly evolving progression of AD, we propose that these hypersensitive responses, now seen in multiple cell populations, may contribute to the negative outcomes that follow acute illness in older patients, including episodes of delirium and the accelerated cognitive trajectory that has been observed in patients who experience delirium before or during their dementia".