Clinical Utility of Amyloid PET Imaging in the Differential Diagnosis of Atypical Dementias and Its Impact on Caregivers

Article type: Research Article

Authors: Bensaïdane, Mohamed Reda^a | Beauregard, Jean-Mathieu^b | Poulin, Stéphane^a | Buteau, François-Alexandre^b | Guimond, Jean^b | Bergeron, David^a | Verret, Louis^{a; c} | Fortin, Marie-Pierre^a | Houde, Michèle^a | Bouchard, Rémi W.^{a; c} | Soucy, Jean-Paul^d | Laforce Jr, Robert^{a; c}

Affiliations: [a] Clinique Interdisciplinaire de Mémoire (CIME), CHU de Québec, QC, Canada | [b] Département d’imagerie médicale, CHU de Québec, QC, Canada | [c] Département des Sciences Neurologiques, Université Laval, QC, Canada | [d] McGill University, QC, Canada

Correspondence: [*] Correspondence to: Mohamed Reda Bensaïdane, MSc, Clinique Interdisciplinaire de Mémoire (CIME), CHU de Québec, 1401, 18ième rue, QC, G1J 1Z4, Canada. Tel.: +1 418 649 5980; Fax: +1 418 649 5981; E-mail: mohamed-reda.bensaidane.1@ulaval.ca; http://www.cliniquedememoire.ca.

Abstract: Recent studies have supported a role for amyloid positron emission tomography (PET) imaging in distinguishing Alzheimer’s disease (AD) pathology from other pathological protein accumulations leading to dementia. We investigated the clinical utility of amyloid PET in the differential diagnosis of atypical dementia cases and its impact on caregivers. Using the amyloid tracer 18F-NAV4694, we prospectively scanned 28 patients (mean age 59.3 y, s.d. 5.8; mean MMSE 21.4, s.d. 6.0) with an atypical dementia syndrome. Following a comprehensive diagnostic workup (i.e., history taking, neurological examination, blood tests, neuropsychological evaluation, MRI, and FDG-PET), no certain diagnosis could be arrived at. Amyloid PET was then conducted and classified as positive or negative. Attending physicians were asked to evaluate whether this result led to a change in diagnosis or altered management. They also reported their degree of confidence in the diagnosis. Caregivers were met after disclosure of amyloid PET results and completed a questionnaire/interview to assess the impact of the scan. Our cohort was evenly divided between positive (14/28) and negative (14/28) 18F-NAV4694 cases. Amyloid PET resulted in a diagnostic change in 9/28 cases (32.1%: 17.8% changed from AD to non-AD, 14.3% from non-AD to AD). There was a 44% increase in diagnostic confidence. Altered management occurred in 71.4% (20/28) of cases. Knowledge of amyloid status improved caregivers’ outcomes in all domains (anxiety, depression, disease perception, future anticipation, and quality of life). This study suggests a useful additive role for amyloid PET in atypical cases with an unclear diagnosis beyond the extensive workup of a tertiary memory clinic. Amyloid PET increased diagnostic confidence and led to clinically significant alterations in management. The information gained from that test was well received by caregivers and encouraged spending quality time with their loved ones.

Keywords: Alzheimer’s disease, Alzheimer variants, amyloid PET imaging, atypical dementia, caregivers, differential diagnosis, frontotemporal lobar degeneration, impact, primary progressive aphasia, clinical utility

DOI: 10.3233/JAD-151180

Journal: Journal of Alzheimer's Disease, vol. 52, no. 4, pp. 1251-1262, 2016