Cited by 47Dementia and Cognitive Impairment ResearchNeuroscience and Neuropharmacology ResearchAlzheimer's disease research and treatments

GABAergic cortical network physiology in frontotemporal lobar degeneration

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Adams, Natalie E, Hughes, Laura E, Rouse, Matthew A, Phillips, Holly N, Shaw, Alexander D, Murley, Alexander G, Cope, Thomas E, Bevan-Jones, W Richard +6 more·2021·Brain

Abstract

The clinical syndromes caused by frontotemporal lobar degeneration are heterogeneous, including the behavioural variant frontotemporal dementia (bvFTD) and progressive supranuclear palsy. Although pathologically distinct, they share many behavioural, cognitive and physiological features, which may in part arise from common deficits of major neurotransmitters such as γ-aminobutyric acid (GABA). Here, we quantify the GABAergic impairment and its restoration with dynamic causal modelling of a double-blind placebo-controlled crossover pharmaco-magnetoencephalography study. We analysed 17 patients with bvFTD, 15 patients with progressive supranuclear palsy, and 20 healthy age- and gender-matched controls. In addition to neuropsychological assessment and structural MRI, participants undertook two magnetoencephalography sessions using a roving auditory oddball paradigm: once on placebo and once on 10 mg of the oral GABA reuptake inhibitor tiagabine. A subgroup underwent ultrahigh-field magnetic resonance spectroscopy measurement of GABA concentration, which was reduced among patients. We identified deficits in frontotemporal processing using conductance-based biophysical models of local and global neuronal networks. The clinical relevance of this physiological deficit is indicated by the correlation between top-down connectivity from frontal to temporal cortex and clinical measures of cognitive and behavioural change. A critical validation of the biophysical modelling approach was evidence from parametric empirical Bayes analysis that GABA levels in patients, measured by spectroscopy, were related to posterior estimates of patients’ GABAergic synaptic connectivity. Further evidence for the role of GABA in frontotemporal lobar degeneration came from confirmation that the effects of tiagabine on local circuits depended not only on participant group, but also on individual baseline GABA levels. Specifically, the phasic inhibition of deep cortico-cortical pyramidal neurons following tiagabine, but not placebo, was a function of GABA concentration. The study provides proof-of-concept for the potential of dynamic causal modelling to elucidate mechanisms of human neurodegenerative disease, and explains the variation in response to candidate therapies among patients. The laminar- and neurotransmitter-specific features of the modelling framework, can be used to study other treatment approaches and disorders. In the context of frontotemporal lobar degeneration, we suggest that neurophysiological restoration in selected patients, by targeting neurotransmitter deficits, could be used to bridge between clinical and preclinical models of disease, and inform the personalized selection of drugs and stratification of patients for future clinical trials.

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  • This approach has been used to study pathophysiology of non-AD dementias and confirmatory studies of drug interventions.

    “This approach has been used to study the pathophysiology of non‐AD dementias, 18 , 19 and confirmatory studies of drug interventions. 5 , 18”

    From Alzheimer's disease and its progression reduce pyramidal cell gain and connectivity (2025) · cites this paper as [18]

    The Introduction describes dynamic causal modelling used to study network physiology in frontotemporal dementia and progressive supranuclear palsy, supporting the non-AD dementia portion. It also describes a placebo-controlled tiagabine experiment, but the Discussion says tiagabine was a pharmacological probe, not a clinical treatment, and that the study was not a clinical trial. It therefore does not support describing this work as a confirmatory study of a drug intervention. (LLM, conf=0.86)

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  • Six of the eight regions are based on prior studies that established a frontotemporal network responsible for generating the mismatch negativity response.

    “Six of these regions are based on a series of prior studies of mismatch negativity generation with healthy adults and those with non‐AD dementia, 4 , 18 , 24 , 25 which established a frontotemporal network (primary auditory, superior temporal, and inferior frontal regions) responsible for generating the mismatch negativity response.”

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Authors
Adams, N. E., Hughes, L. E., Rouse, M. A., Phillips, H. N., Shaw, A. D., Murley, A. G., Cope, T. E., Bevan-Jones, W. R., Passamonti, L., Street, D., Holland, N., Nesbitt, D., Friston, K., & Rowe, J. B.
Affiliations
  • University of Cambridge (GB)
  • MRC Cognition and Brain Sciences Unit (GB)
  • Wellcome Centre for Human Neuroimaging (GB)
Corresponding author
Rowe, James B
Venue
Brain
Published
2021-03-12
Volume
144
Issue
7
Pages
2135-2145
ISSN
  • 0006-8950 (ISSN-L)
  • 1460-2156
OpenAlex
W3134821755
Cited by
47
References
82
Citations by year
2026: 4 · 2025: 9 · 2024: 9 · 2023: 10 · 2022: 11 · 2021: 4
FWCI
6.05
Type
journal article
Language
en
Open access
Locations
  • Brain (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • ORCA Online Research @Cardiff (Cardiff University) (acceptedVersion)
  • UCL Discovery (University College London) (submittedVersion)
  • Figshare (submittedVersion, cc-by)
  • Open Research Exeter (University of Exeter) (submittedVersion, cc-by)
  • Apollo (University of Cambridge) (submittedVersion, cc-by)
  • Apollo (cc-by)
Funders
  • Wellcome Trust (103838)
  • National Institute for Health Research Cambridge Biomedical Research Centre (BRC-1215-20014)
  • Medical Research Council (MC_U105597119, MC_U_00005/12, SUAG/004/91365, SUAG/051 G101400)
  • Association of British Neurologists
  • Holt Fellowship
  • National Institute for Health Research
  • Department of Health and Social Care
Topics
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
Keywords
frontotemporal lobar degeneration, behavioral variant frontotemporal dementia, progressive supranuclear palsy, GABAergic dysfunction, tiagabine, GABA reuptake inhibition, dynamic causal modeling, GABA levels, treatment response variability
MeSH terms
Tiagabine, Aged, Cerebral Cortex, Double-Blind Method, Female, gamma-Aminobutyric Acid, Humans, Magnetic Resonance Imaging, Male, Models, Neurological, Nerve Net, Synaptic Transmission, Magnetic Resonance Spectroscopy, Supranuclear Palsy, Progressive, Magnetoencephalography, Cross-Over Studies, Frontotemporal Dementia, GABA Uptake Inhibitors

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