Study: Memory Loss Is Not The Only Alzheimer Symptom

Relying solely on symptoms of memory loss as a way to diagnose Alzheimer disease may lead to missing other forms of dementia caused by the disease, according to a new study.

A group including researchers from Northwestern University sought to identify features of primary progressive aphasia (PPA) associated with Alzheimer disease (AD) neuropathology, as well as determining whether logopenic PPA is a clinical marker for AD. A total of 139 prospectively enrolled participants with a root diagnosis of PPA comprised the investigators' reference set. Those with autopsy or biomarker evidence of AD, and who had been evaluated at mild disease stages (19 participants) were included. All had quantitative language testing and APOE genotyping, and 15 had magnetic resonance imaging (MRI) morphometry, according to the authors.
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Overall, impaired word-finding was the universal presenting complaint in the aphasic AD group, and fluency, repetition, naming, and grammaticality ranged from preserved to severely impaired. All had relative preservation of word comprehension, noted the researchers, adding that 8 of the 15 aphasic participants with AD showed no appreciable cortical atrophy at the individual level on MRI. As a group, atrophy was asymmetrically concentrated in the left perisylvian cortex.

"It is important for primary care physicians to know that Alzheimer disease does not always present with memory loss," said Emily Rogalski, PhD, associate professor at Northwestern University's Cognitive Neurology and Alzheimer Disease Center, and lead author of the study.

"Individuals can present with changes in language or other cognitive abilities," continued Rogalski, noting that symptom presentation depends on where the disease is occurring in the brain as opposed to the type of neuropathology.

"Treatments often target a specific neuropathological species," she said. "We now have tools that are emerging, like amyloid PET imaging, that will aid physicians with the differential diagnosis. These tools can also be used to guide medication decisions and enrollment into clinical trials."

—Mark McGraw

Reference:

Rogalski E, Sridhar J, Rader B, et al. Aphasic variant of Alzheimer disease: clinical, anatomic, and genetic features [published online August 26, 2016]. Neurology. doi:http:/​/​dx.​doi.​org/​10.​1212/​WNL.​0000000000003165.