Summary:

- The article discusses a new study published in the journal Nature Medicine that found evidence of a potential new cause of Alzheimer's disease.

- The study suggests that a protein called APOE4, which is a known genetic risk factor for Alzheimer's, may contribute to the disease by disrupting the normal functioning of the brain's immune cells called microglia.

- The findings provide new insights into the underlying mechanisms of Alzheimer's and could potentially lead to the development of new therapies targeting the APOE4 protein and its effects on microglia.