Progress in Brain Imaging for Alzheimer Diagnosis

In this video, Liana G. Apostolova, MS, MD, FAAN, Distinguished Professor, Barbara and Peer Baekgaard Professor of Alzheimer's Disease Research, Indiana University, Indianapolis, IN, recaps her virtual Neurology Week presentation titled “Brain Imaging in the Diagnosis of Dementia and Alzheimer's Disease.” 

Read the Transcript:

Dr Liana Apostolova:  Hello. I'm Liana Apostolova. I'm the Indiana University Distinguished Professor and the Barbara and Peer Baekgaard Professor of Alzheimer's Disease Research at Indiana University. I'm planning to give you a short recap of Neurology Week regarding brain imaging progress in Alzheimer's disease.

In the past few decades, Alzheimer's disease has been revolutionized by progress in imaging biomarkers. Back in the days when I was starting my research career, there was only magnetic resonance imaging and FDG-PET scans.

Now, we have the opportunity to visualize the molecular pathology behind Alzheimer's disease, the presence of amyloid plaques and tau tangles, in a very unprecedented way in the living human subject. This has certainly also provided an opportunity for us physicians to make an accurate diagnosis, improve our diagnostic accuracy.

Without biomarkers, our diagnostic accuracy predicting who truly has Alzheimer's disease post-mortem is only about 75%. Now that we have these molecular imaging biomarkers, we, of course, our certainty, our sensitivity and specificity, has tremendously increased to above 95%.

We can use either amyloid or tau imaging biomarkers, and both show this very excellent specificity and sensitivity. That also allowed us to capture disease heterogeneity because the patients on the Alzheimer spectrum, that is, those that have positive amyloid PET scans, could have a variable presentation in terms of atrophy, hypometabolism, and even tau deposition.

There are certain subtypes of amyloid-positive participants that are now being defined and follow-up and characterized using the ATN research framework, where A stands for amyloid, T stands for tau, and N stands for neurodegeneration.

Quite a bit of research is ongoing in this field. Those who have all three biomarkers obviously positive are the ones that fare pretty poorly with the fastest rates of progression, followed by those with amyloid and tau only.

That is certainly a great literature for everyone to familiarize themselves with. Then an important area where especially these biomarkers in the in vivo pathological validation would be truly helpful is the atypical Alzheimer's disease variants.

There is a very nice overview of those several variants with very important references also outlined in my presentation in the way that biomarkers can help us get to their ultimate accurate diagnosis so that we can start treatment or enroll them in clinical trials to advanced treatment altogether.

Lastly, I was discussing the fact that, by and large, pure Alzheimer's disease is very rare. Only about 19% of those who come to autopsy have just amyloid and tau deposition. The vast majority of participants that die with Alzheimer's disease have additional protein deposits.

I was showing some excellent data that highlights the need for additional imaging and fluid biomarkers that can help us characterize the multiproteinopathy issue. That might be also what's underlying the variability in Alzheimer's disease.