The 4 Rarer Kinds of Dementia Most People Don't Know Exist

Posterior cortical atrophy (PCA) mainly impairs visual and spatial functioning.

In PCA, memory is less affected early on than in Alzheimer's; symptoms commonly begin between ages 55 and 65.

People with PCA can experience visual hallucinations and difficulty with spatial navigation.

PCA is rare; its brain changes closely resemble Alzheimer's and researchers are determining whether it's a distinct subtype or an atypical form; an estimated 5–15% of people with Alzheimer's have PCA.

Creutzfeld-Jakob disease is a prion disease and is particularly rare, affecting about one in 1 million people worldwide.