How does Alzheimer disease affect the ability to retain new information?

In Alzheimer disease, the ability to retain new information is significantly impaired due to massive cell loss and structural damage within the hippocampus, a brain region essential for forming new memories.3

This impairment typically manifests in the early stages of the disease, often beginning as forgetfulness during a transitional period known as amnestic mild cognitive impairment (MCI). As the disease progresses, the brain experiences widespread neuropathological changes, including the accumulation of neuritic plaques and neurofibrillary tangles, as well as a deficiency in the neurotransmitter acetylcholine, which is critical for memory function. These physiological disruptions prevent the brain from effectively encoding and storing new fact- and event-related (declarative) memories, leading to the severe memory deficits characteristic of the condition.123