Alzheimer disease as the most common dementia cause

Summary

Alzheimer’s disease (AD) is the most common cause of dementia, responsible for about 60–70% of cases. It is a progressive neurodegenerative disorder that typically begins after age 65, though a smaller portion of cases can start earlier (early-onset). The earliest and most noticeable symptom is usually difficulty remembering recent events, and as the disease advances it can include language problems, disorientation (including getting lost), mood and behavioral changes, and increasing loss of independence. Pathologically, AD is characterized by the accumulation of abnormal protein deposits in the brain—amyloid plaques (amyloid beta) and neurofibrillary tangles (tau). These misfolded aggregates disrupt normal neuronal function and connections, leading to irreversible neuron degeneration over time. Diagnosis is based on clinical history and cognitive testing, with medical imaging and blood tests used to rule out other causes; definitive confirmation requires post-mortem examination of brain tissue. There is currently no known treatment that can stop or reverse AD progression, though some medications may temporarily improve symptoms. Worldwide, AD affects tens of millions of people, making it a major public health concern and a leading cause of death among dementias.

Key Points

• 1

  Alzheimer’s disease accounts for the majority of dementia cases (about 60–70%).

• 2

  Early symptoms often involve short-term memory problems, with later progression to language, disorientation, behavioral changes, and loss of independence.

• 3

  AD is driven by abnormal amyloid beta and tau protein accumulation, and diagnosis relies on clinical assessment supported by tests that exclude other causes.