April 02, 2019
2 min read

Amyloid PET scans improve dementia diagnosis, management

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Image of Gil Rabinovici
Gil Rabinovici

Amyloid positron emission tomography, or PET, changed the clinical management in most patients with mild cognitive impairment and most patients with dementia of uncertain cause after 90 days, according to findings published in JAMA.

“Accurate diagnoses are critical to ensure patients are receiving the most appropriate treatments,” Gil D. Rabinovici, MD, from the Memory and Aging Center at UCSF, said in a press release. “An early, definitive diagnosis may allow individuals to be part of planning for the next phase of their lives and to make decisions that otherwise would eventually need to be made by others.”

Rabinovici and colleagues reported findings from the Imaging Dementia—Evidence for Amyloid Scanning (IDEAS) study, a multisite longitudinal study that examined the link between amyloid PET and subsequent changes in patient management among Medicare beneficiaries with mild cognitive impairment (MCI) or dementia of uncertain etiology.

Participants underwent amyloid PET at more than 340 imaging centers. Dementia specialists recorded participants’ diagnosis and management plan before and 90 days after PET to determine change in management between visits, which was evaluated via a composite outcome that included Alzheimer’s disease drug therapy, other drug therapy and safety/future planning counseling. The researchers also reported the proportion of changes in diagnosis from Alzheimer’s disease to non-Alzheimer’s disease (and vice versa) before and after PET visits.

Of 11,409 participants included in the analysis, 3,817 patients with MCI (55.3%) and 3,154 patients with dementia (70.1%) had positive amyloid PET results.

multiple images of a brain scan 
Amyloid PET changed the clinical management in most patients with mild cognitive impairment and most patients with dementia, according to study findings.
Source: Adobe Stock

Rabinovici and colleague found that clinical management 90 days after amyloid PET changed in 4,159 of 6,905 patients with MCI (60.2%; 95% CI, 59.1-61.4) and in 2,859 of 4,504 patients with dementia (63.5%; 95% CI, 62.1-64.9), which exceeded the 30% threshold in each group (P < .001).

“The scale of the clinical changes spurred by amyloid PET imaging were twice as great as we had anticipated,” Rabinovici told Healio Psychiatry. “Based on the current findings, the expanded availability of these tests would have a major impact on patients by ensuring they get the right diagnosis, the right medications and have the opportunity to enroll in relevant clinical trials.”

The researchers also found that management after amyloid PET in etiologic diagnosis changed from Alzheimer disease to non-Alzheimer’s disease in 2,860 of 11,409 patients (25.1%; 95% CI, 24.3-25.9) and from non-Alzheimer’s disease to Alzheimer’s disease in 1,201 of 11,409 (10.5%; 95% CI, 10-11.1%).

“This research demonstrates that the availability of amyloid PET imaging can have a significant impact on how physicians care for patients with memory loss and cognitive impairment,” Rabinovici said. “Beyond purely clinical considerations, I think people with Alzheimer’s disease deserve the opportunity to know what they are facing and to make informed plans for the future with their families and loved ones.”

These results show that more knowledge about etiology provided by amyloid PET, above the current clinical care standards, can affect the clinical management of patients with cognitive impairment, Clifford R. Jack Jr., MD, and Ronald C. Petersen, MD, PhD, from Mayo Clinic, wrote in a related comment.

“More detailed etiologic characterization by deeper biomarker-based phenotyping will result in more precise, patient-specific management decision making,” they wrote. “Ultimately, the hope is that management will include access to pathophysiologically appropriate, disease-modifying interventions.” – by Savannah Demko

Disclosures: Rabinovici reports numerous relevant financial disclosures; please see the study for all authors’ relevant financial disclosures. Jack and Petersen report numerous relevant financial disclosures; please see the related comment.