Cancer survivors may be less likely to develop dementia, research shows

Researchers report that a protein called cystatin C, released by cancer cells and described in a study published in Cell, reduced amyloid plaques and improved memory in mice; the findings come from animal experiments and human relevance is not yet established.

Researchers are examining a long-standing observation that people who survive cancer appear less likely to develop dementia later in life. Multiple studies over the past two decades have reported about a 25% lower dementia risk after a cancer diagnosis. A team at Huazhong University of Science and Technology published work in the journal Cell identifying a cancer-released protein called cystatin C. Their experiments in mice suggest the protein can reach the brain and interact with abnormal protein deposits linked to dementia. What researchers reported: - Multiple studies over the past 20 years have observed roughly a 25% lower dementia risk following a cancer diagnosis. - The Huazhong University team identified cystatin C, a protein secreted by cancer cells, and reported the work in Cell. - In mouse models, transplanting human tumours was associated with reduced formation of amyloid plaques linked to dementia. - Injecting cystatin C into mice with dementia-like deposits was reported to reduce plaques and to improve measures of memory and learning. - Other cancer-related molecules, including PIN1 and the enzyme PI3K, are also under investigation for possible protective effects. - The reported findings come from animal studies, and it is not yet certain whether the same processes occur in humans. Summary: The animal research identifies cystatin C as a candidate mechanism that may help explain why cancer survivors have shown lower rates of dementia in some studies, and shows plaque reduction and cognitive improvement in mice. Experts caution that cystatin C may not be the only factor involved. Further studies are planned to explore the mechanism and its relevance to people.