Frontotemporal dementia syndromes form a genetically, clinically and radiologically heterogeneous group of conditions. The main phenotypes display strikingly different burdens of disease, with a predilection for specific brain regions and relative sparing of others, yet the apparent selectivity of cerebral involvement has not been fully elucidated.

The research team, led by Marlene Tahedl and Peter Bede with colleagues, undertook a prospective neuroimaging study using a uniform imaging protocol to characterise atrophy patterns in four syndromes: ALS-FTD, behavioural variant FTD, nonfluent variant primary progressive aphasia and semantic variant primary progressive aphasia.

Within ALS-FTD, the investigators separated participants according to C9orf72 status. In patients without the C9orf72 expansion (ALSFTD-C9NEG), associations were noted with GABAergic, opioid, cannabinoid, microglial and acetylcholine systems. In those carrying the expansion (ALSFTD-C9POS), correlations were observed with opioid, glutaminergic and synaptic vesicle glycoprotein 2A receptor populations.

Atrophy in behavioural variant FTD showed a predilection for serotonergic, glutaminergic, opioid, GABAergic and cannabinoid circuits. Volume loss in nonfluent variant primary progressive aphasia colocalised with an even broader set of networks, spanning GABAergic, opioid, microglial, serotonergic, cannabinoid, acetylcholine, glutaminergic and dopaminergic systems.

Semantic variant primary progressive aphasia likewise implicated a multitude of neurotransmitter populations, including opioid, serotonergic, GABAergic, dopaminergic and microglial systems. To reach these results, the authors systematically evaluated anatomical correlations between focal volume loss and a large panel of neurotransmitters, ranking the associations across the phenotypes.

The authors emphasise that their findings are spatial associations rather than demonstrations of mechanism. The study indicates that the distinctive neuroimaging signatures of FTD phenotypes exhibit spatial associations with physiological neurotransmitter receptor density maps, and that the propensity of atrophy to affect particular brain regions in FTD subtypes may be defined by neurotransmitter populations.

The researchers note that their results indirectly support the notion of neurotransmitter-system defined connectivity-based disease propagation in FTD. Because the work is an observational imaging study, it identifies colocalisation patterns rather than causal pathways, and the abstract does not report clinical outcomes or therapeutic implications. Even so, mapping atrophy onto receptor architecture offers a framework for understanding why particular syndromes strike particular networks, and the findings may inform future hypotheses about how neurodegeneration selects its targets in frontotemporal lobar degeneration.

Subject of Research: Spatial associations between brain atrophy patterns in frontotemporal dementia syndromes and neurotransmitter receptor expression maps

Article Title: Neurotransmitter-defined cerebral vulnerability patterns in frontotemporal lobar degeneration (FTLD)

Article References: Tahedl, M., Toomey, A., Mandal, N., Mangan, S., Siah, W. F., Tan, E. L., Hardiman, O., Kleinerova, J., McKenna, M. C., Hutchinson, S., Lope, J., & Bede, P. (2026). Neurotransmitter-defined cerebral vulnerability patterns in frontotemporal lobar degeneration (FTLD). Journal of Neurology, 273(11), Article 673. https://doi.org/10.1007/s00415-026-14216-y

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14216-y

Keywords: frontotemporal dementia, ALS-FTD, primary progressive aphasia, neuroimaging, atrophy, neurotransmitter receptors, GABAergic, serotonergic, opioid systems, disease propagation, behavioral variant FTD, Journal of Neurology