Daijiworld Media Network - Los Angeles

Los Angeles, Apr 29: A new study has identified three distinct trajectories of cognitive decline in patients at risk of Alzheimer's disease—stable, slow decline, and fast decline—highlighting the variability in how the condition progresses.

The research, conducted by scientists at the University of Southern California, analysed brain scans of over 1,100 individuals in the United States who had elevated levels of amyloid protein deposits, a hallmark of Alzheimer’s, but were still cognitively unimpaired.

Alzheimer’s disease is a neurodegenerative condition in which memory and thinking abilities progressively deteriorate, eventually affecting daily functioning. Brain scans typically reveal abnormal protein build-ups such as amyloid and tau.

The study found that individuals who experienced gradual or rapid cognitive decline had higher levels of tau and phosphorylated tau (P-tau217), compared to those who remained stable. Additionally, these participants showed a smaller hippocampus, a brain region critical for memory and among the first to be affected in the disease.

The findings, published in Alzheimer's & Dementia, underscore that Alzheimer’s progression is not uniform across patients.

Lead author Michael Donohue noted that most studies focus on average outcomes, which can obscure significant differences among individuals. “This suggests that Alzheimer’s disease is more variable than often depicted,” he said.

Researchers also highlighted that this is among the first studies to link patterns of cognitive decline with biological markers such as phosphorylated tau.

Using a combination of blood tests and brain imaging, the team was able to classify participants into stable or declining groups with about 70 per cent accuracy.

The findings also point to challenges in early-stage Alzheimer’s research, as some individuals may remain stable without treatment, making it harder to assess the effectiveness of new therapies.

The researchers suggested that future clinical trials should focus more on individual patterns of decline rather than average results to better understand and treat the disease.