Alzheimer’s disease (AD),

Alzheimer’s disease (AD), a disease of the neurological system, is the most common form of dementia. The early stages of AD affect the portions of the brain that control thought, memory, and language. As the disease progresses, patients may experience difficulties talking, reading, writing, and recognizing people they know.

AD has been linked to the development of two abnormalities in the brain: amyloid plaques, which form outside neurons, and tau tangles, which form inside the cells. The preclinical phase of the disease begins when evidence of either amyloid or tau pathology is detected. During this stage, which can last many years, signs of cognitive decline are rare, making early diagnosis of the disease difficult.