Relying on clinical symptoms of memory loss to diagnose Alzheimer’s disease may miss other forms of dementia caused by Alzheimer’s that don’t initially affect memory, reports a new study published in the journal Neurology.

There is more than one kind of Alzheimer’s disease. Alzheimer’s can cause language problems, disrupt an individual’s behavior, personality and judgment or even affect someone’s concept of where objects are in space. If it affects personality, it may cause lack of inhibition.

This all depends on what part of the brain it attacks. A definitive diagnosis can only be achieved with an autopsy. Emerging evidence suggests an amyloid PET scan, an imaging test that tracks the presence of amyloid — an abnormal protein whose accumulation in the brain is a hallmark of Alzheimer’s — may be used during life to determine the likelihood of Alzheimer’s disease pathology.

In the study, the authors identified the clinical features of individuals with primary progressive aphasia (PPA), a rare dementia that causes progressive declines in language abilities due to Alzheimer’s disease. Early on in PPA, memory and other thinking abilities are relatively intact.

PPA can be caused either by Alzheimer’s disease or another neurodegenerative disease family called frontotemporal lobar degeneration. The presence of Alzheimer’s disease was assessed in this study by amyloid PET imaging or confirmed by autopsy.

The study demonstrates that knowing an individual’s clinical symptoms isn’t sufficient to determine whether someone has PPA due to Alzheimer’s disease or another type of neurodegenerative disease. Therefore, the authors say, biomarkers, such as amyloid PET imaging, are necessary to identify the neuropathological cause.

Paper: “Aphasic variant of Alzheimer disease”
Reprinted from materials provided by Northwestern University.

noiembrie 4, 2016