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Apathy doubles Alzheimer's risk
Those people had no dementia and no diagnosis of any neurological disorder. Studies over the last few years keep finding the link, and it points to Alzheimer's disease affecting behavior long before it shows up as cognitive impairment. Loss of motivation is one of the early behavioral changes.
The timeline makes that important. The amyloid and tau laid down in the brain can build for more than 10 years, perhaps more than 15, before anyone presents to a doctor with cognitive complaints. That is a window of 10 to 15 years in which apathy might be a detectable sign. Monoclonal antibodies that mop up amyloid have shown small improvements in the course of established early Alzheimer's disease.
Why does Alzheimer's pathology build silently for years?
In 2010, Clifford Jack and colleagues proposed in Lancet Neurology a model in which amyloid accumulation begins first, followed by tau changes, shrinking of brain tissue, and finally memory decline. Each step runs a long time ahead of the next. The long lag explains why PET scans can show amyloid in people who have no symptoms.
How do amyloid-clearing antibodies work?
Monoclonal antibodies such as lecanemab bind to clumped amyloid and mark it for the brain's immune cells, called microglia, to clear. In the 2022 CLARITY AD trial, lecanemab slowed decline on a clinical rating scale by 27 percent over 18 months in people with early Alzheimer's disease. The trial also recorded brain swelling and small bleeds as side effects in some participants.
How is apathy measured in older adults?
Apathy is usually scored with questionnaires that ask about interest, initiative, and emotional responses. Robert Marin developed the Apathy Evaluation Scale in 1991, with versions filled in by the person, a caregiver, or a clinician. A high score reflects less goal-directed behavior and thinking than the person showed before.
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