Alzheimer disease

What it means

A degenerative disease of the brain characterized by the insidious onset of dementia. Impairment of memory, judgment, attention span, and problem solving skills are followed by severe apraxia and a global loss of cognitive abilities. The condition primarily occurs after age 60, and is marked pathologically by severe cortical atrophy and the triad of senile plaques, neurofibrillary tangles, and neuropil threads.

Note that this is a bundled term that refers to a disease rather than to phenotypic features. It is retained for convenience since Alzheimer disease is used for annotation of other diseases (e.g., Down syndrome) as if it were a feature. If possible it is preferable to annotate with the precise phenotypic features.

Rare diseases that can present with this3

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category