Early amyloid PET provides high diagnostic confidence for adults with cognitive impairment

Key takeaways:

• At 3 months, 40% of participants who underwent PET within 1 month of workup had a diagnosis with very high confidence vs. 11% whose PET occurred later.
• Findings were consistent across all cognitive stages.

Access to early amyloid position emission tomography allowed those with memory issues to receive a diagnosis with very high confidence at 3 months compared with those who did not undergo PET, according to research in JAMA Neurology.

“Amyloid deposition in the brain is one of the main hallmarks of Alzheimer’s disease and is considered one of the strongest risk factors of dementia,” Daniele Altomare, PhD, of the Geneva Memory Center in Switzerland, and colleagues wrote. “Despite the increasing use of amyloid PET in clinical practice, real-world evidence about its clinical utility and cost-effectiveness is still limited.”

Altomare and colleagues sought to assess the clinical effect of amyloid detection via PET in the prospective, randomized AMYPAD-DPMS trial, which was conducted at eight European academic memory clinics. They included 840 adults diagnosed with subjective cognitive decline plus clinical features that increase the possibility of preclinical AD (SCD+), mild cognitive impairment (MCI) or dementia.

Researchers divided participants into three groups based on amyloid PET performance: arm 1 (n = 291), in which PET took place within 1 month of diagnostic workup; arm 2 (n = 271), in which PET occurred later (mean of 8 months) and arm 3 (n = 278), in which PET was performed at the discretion of the managing physician. Participants were evaluated at baseline, after 3 months and up to 18 months (only for arm 1, not mandatory).

The primary outcome was the difference between arms 1 and 2 in proportion of participants receiving an etiological diagnosis with very high confidence (at least 90%) after 3 months.

According to results, baseline and 3-month data were available for 272 participants in arm 1 (mean age, 71 years; 55% men) and 260 in arm 2 (mean age, 71 years; 52% men). At 3 months, 40% of participants in arm 1 (n = 109) had a diagnosis with very high confidence compared with 11% in arm 2 (n = 30).

Researchers reported this finding was consistent among all cognitive stages between arms (SCD+: 30% vs. 6%; MCI: 42% vs. 9%; and dementia: 49% vs. 20%; all P < .001).

“A timely high-confidence diagnosis is critical to the efficacy of disease-modifying therapies, especially anti-amyloid drugs, whose efficacy might decrease with advancing disease progression,” Altomare and colleagues wrote.