The study, published in European Radiology, analyses brain asymmetries in patients with frontotemporal dementia and Alzheimer’s disease. Using these data, the research team has managed to create an index—the Cortical Asymmetry Index (CAT)—that examines the magnetic resonance images of these patients.
The research was carried out by Agnès Pérez-Millan, from the Alzheimer’s Disease and other Cognitive Disorders research group and led by Dr. Raquel Sánchez-Valle, head of the research group.
A total of 101 patients with frontotemporal dementia, 230 with Alzheimer’s disease, and 173 healthy subjects were studied. This index, developed by this research group, was used to analyse the magnetic resonance images of the study participants.
This index has made it possible to successfully differentiate between people with Alzheimer’s disease, those with frontotemporal dementia, and healthy individuals. Furthermore, it has made it easier to distinguish between subtypes of frontotemporal dementia, especially the semantic variant, which is characterized by a loss of speech, and the behavioural variant, which involves changes in the person’s personality and behaviour.
It was seen that, the greater the brain asymmetry, the more advanced the frontotemporal dementia and the higher the levels of neurofilaments, a protein that measures brain degeneration. These data were corroborated by monitoring patients for two years after the study. The results indicate that measuring asymmetry using this index allows the progression of frontotemporal dementia to be quantified and monitored.
Quantifying in order to understand
In this project, artificial intelligence algorithms were used with the cortical asymmetry index. This made it possible to identify subgroups of patients with frontotemporal dementia and Alzheimer's disease who showed biological differences, in addition to their differences in brain asymmetry. The learning resulting from this process was uploaded to open-source platforms, so that other researchers can access the computer code of this index and apply it to analyse their images.
This breakthrough is important because, unlike in the case of Alzheimer’s disease, there are no reliable diagnostic biomarkers to confirm that an individual has frontotemporal dementia. The usual form of diagnosis is based on the symptoms being assessed and the imaging evidence being examined qualitatively by specialized healthcare professionals.
Impact of frontotemporal dementia
Frontotemporal dementia is a group of neurodegenerative diseases, distinct from Alzheimer’s disease. The most common symptoms of this disease are a sudden change in personality and behaviour of the affected person, accompanied by language difficulties. However, unlike Alzheimer’s disease, memory can be relatively preserved.
It is the second most common form of neurodegenerative dementia in people under 65 years of age. This has a major impact on their family and working life.
It is currently considered a minority disease, probably because it is underdiagnosed. For this reason, quantitative data are needed to improve the diagnosis and monitoring of frontotemporal dementia, as well as to contribute to a better understanding of this disease.
Reference article:
https://link.springer.com/article/10.1007/s00330-025-11400-y
Pérez-Millan, A., Lal-Trehan Estrada, U.M., Falgàs, N. et al. The Cortical Asymmetry Index for subtyping dementia patients. Eur Radiol (2025). https://doi.org/10.1007/s00330-025-11400-y
