The new research reinforces how complex the neurodevelopmental disorder is and that there isn’t a single cause.

(CNN) -- Alzheimer's disease may be inherited more often than previously known, according to a new study that paints a clearer picture of a gene long known to be linked to the common form of dementia.

Among people diagnosed with Alzheimer’s, researchers recognize familial forms of the disease and sporadic cases. Most cases are thought to be sporadic, which develop later in life. Familial forms, ...

In the large dataset of nearly 3,300 brains kept by the National Alzheimer’s Coordinating Center, for example, 273 individuals had two copies of the APOE4 gene, and 240, or 88%, had dementia. When ...