Amyloid PET changes 25% of dementia diagnoses, decreases patient uncertainty

Researchers from VU Medical Center in Amsterdam demonstrated that implementing amyloid PET imaging as a diagnostic tool in daily clinical practice and not just in clinical research cohorts may be associated with changes in diagnosis and treatment for dementia patients, according to new research published June 11 in JAMA Neurology.  

Specifically, amyloid-positive and amyloid-negative results had substantial associations with these changes, wrote lead author Arno de Wilde, MD.  

The researchers found that 25 percent of study participants had their diagnosis changed more often because of negative PET results and when results were disclosed, diagnostic uncertainty among participants decreased. 

"We found in a large and unselected memory clinic cohort that both amyloid-positive and amyloid-negative results led to changes in etiological diagnosis, diagnostic confidence and patient treatment," de Wilde and colleagues wrote. "The association of amyloid PET was observed in all diagnostic groups, encompassing the spectrum of dementia, mild cognitive impairment (MCI) and subjective cognitive decline (SCD)."  

As part of the Alzheimer Biomarkers in Daily Practice (ABIDE) project, de Wilde and colleagues offered amyloid PET scans to 507 patients (39 percent women, average age of 65 years) who visited the VU University Medical Center and University Medical Center Utrecht memory clinics in the Netherlands between January 2015 and December 2016.  

The researchers determined a pre-amyloid and post-amyloid PET diagnosis that existed of both a clinical syndrome (dementia, MCI or SCD) and a suspected etiology (Alzheimer disease [AD] or non-AD), with a confidence level ranging from 0 percent to 100 percent, the researchers wrote. Each patient then received treatment options and a clinical follow-up one year after examination.  

Of the 507 patients, 32 percent had Alzheimer disease (AD) dementia, 14 percent had non-AD dementia, 23 percent had mild cognitive impairment, and 31 percent had subjective cognitive decline. Additionally, amyloid PET results were positive for 48 percent of patients.   

For 25 percent of patients, the suspected etiology changed after undergoing amyloid PET more often because of negative PET results. This was found to occur more frequently in patients older than 65. 

Additionally, 11 percent of patients had a change in treatment post-PET, according to the authors.  

Because amyloid PET is becoming increasingly available, the researchers believe it's important to gather clinical data from individuals with SCD to predict clinical outcomes.  

"Currently, there is insufficient longitudinal data to interpret the predictive value of amyloid PET in SCD," the researchers wrote. "Long-term follow-up is needed to evaluate how amyloid PET can help predict clinical outcomes, especially given the evidence that amyloid-positive patients with SCD have a higher risk of progressing to dementia."