Network degeneration and dysfunction in presymptomaticC9ORF72expansion carriers.
Hexanucleotide repeat expansions inC9ORF72are the most common known genetic cause of familial and sporadic frontotemporal dementia and amyotrophic lateral sclerosis. Previous work has shown that patients with behavioral variant frontotemporal dementia due toC9ORF72show salience and sensorimotor network disruptions comparable to those seen in sporadic behavioral variant frontotemporal dementia, but it remains unknown how early in the lifespan these and other changes in brain structure and function arise. To gain insights into this question, we compared 15 presymptomatic carriers (age 43.7 ± 10.2 years, nine females) to matched healthy controls. We used voxel-based morphometry to assess gray matter, diffusion tensor imaging to interrogate white matter tracts, and task-free functional MRI to probe the salience, sensorimotor, default mode, and medial pulvinar thalamus-seeded networks. We further used a retrospective chart review to ascertain psychiatric histories in carriers and their non-carrier family members. Carriers showed normal cognition and behavior despite gray matter volume and brain connectivity deficits that were apparent as early as the fourth decade of life. Gray matter volume deficits were topographically similar though less severe than those in patients with behavioral variant frontotemporal dementia due toC9ORF72, with major foci in cingulate, insula, thalamus, and striatum. Reduced white matter integrity was found in the corpus callosum, cingulum bundles, corticospinal tracts, uncinate fasciculi and inferior longitudinal fasciculi. Intrinsic connectivity deficits were detected in all four networks but most prominent in salience and medial pulvinar thalamus-seeded networks. Carrier and control groups showed comparable relationships between imaging metrics and age, suggesting that deficits emerge during early adulthood. Carriers and non-carrier family members had comparable lifetime histories of psychiatric symptoms. Taken together, the findings suggest that presymptomaticC9ORF72expansion carriers exhibit functionally compensated brain volume and connectivity deficits that are similar, though less severe, to those reported during the symptomatic phase. The early adulthood emergence of these deficits suggests that they represent aberrant network patterning during development, an early neurodegeneration prodrome, or both.
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Suzee E
SE
Lee
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Ana C
AC
Sias
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Maria Luisa
ML
Mandelli
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Jesse A
JA
Brown
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Alainna B
AB
Brown
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA; Stanford University, Department of Psychology, Jordan Hall, 450 Serra Mall, Stanford, CA 94305, USA.
Anna M
AM
Khazenzon
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Anna A
AA
Vidovszky
University of California, San Francisco, Department of Neurology, 675 Nelson Rising Lane, MC: 0444, San Francisco, CA 94158, USA.
Theodore P
TP
Zanto
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Anna M
AM
Karydas
Department of Neurology and Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, 760 Westwood Plaza Los Angeles, CA 90024, USA.
Mochtar
M
Pribadi
Department of Neurology and Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, 760 Westwood Plaza Los Angeles, CA 90024, USA.
Deepika
D
Dokuru
Department of Neurology and Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, 760 Westwood Plaza Los Angeles, CA 90024, USA.
Giovanni
G
Coppola
Department of Neurology and Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, 760 Westwood Plaza Los Angeles, CA 90024, USA.
Dan H
DH
Geschwind
Mayo Clinic, Department of Neuroscience, Birdsall Research Building 207, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
Rosa
R
Rademakers
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Maria Luisa
ML
Gorno-Tempini
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Howard J
HJ
Rosen
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA.
Bruce L
BL
Miller
University of California, San Francisco, Memory and Aging Center, Department of Neurology, 675 Nelson Rising Lane, MC:1207, San Francisco, CA 94158, USA; University of California, San Francisco, Department of Pathology, 675 Nelson Rising Lane, Suite 140, MC:1207, San Francisco, CA 94158, USA.
William W
WW
Seeley
D000328:Adult; D000690:Amyotrophic Lateral Sclerosis / Q000000981:diagnostic imaging* / Q000235:genetics*; D058070:Asymptomatic Diseases; D001921:Brain / Q000000981:diagnostic imaging; D000073885:C9orf72 Protein; D042622:DNA Repeat Expansion / Q000235:genetics*; D056324:Diffusion Tensor Imaging; D005260:Female; D057180:Frontotemporal Dementia / Q000000981:diagnostic imaging* / Q000235:genetics*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000000981:diagnostic imaging; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D011506:Proteins / Q000235:genetics*
D000073885:C9orf72 Protein; C568651:C9orf72 protein, human; D011506:Proteins; D010100:Oxygen
ALS, amyotrophic lateral sclerosis; Amyotrophic lateral sclerosis; CDR, Clinical Dementia Rating scale; DMN, default mode network; Diffusion tensor imaging; FA, fractional anisotropy; FTD, frontotemporal dementia; FWE, familywise error; Frontotemporal dementia; Functional MRI; Genetics; HC, healthy control; ICN, intrinsic connectivity network; IRI, Interpersonal Reactivity Index; MMSE, Mini-Mental State Exam; MND, motor neuron disease; NPI, Neuropsychiatric Inventory; ROI, region of interest; SMN, sensorimotor network; TIV, total intracranial volume; VBM, voxel-based morphometry; bvFTD, behavioral variant frontotemporal dementia; fMRI, functional MRI; preSxC9, presymptomatic C9ORF72 expansion carriers