Atrophy patterns in histologic vs clinical groupings of frontotemporal lobar degeneration.
OBJECTIVE
Predictable patterns of atrophy are associated with the clinical subtypes of frontotemporal dementia (FTD): behavioral variant (bvFTD), semantic dementia (SEMD), and progressive nonfluent aphasia (PNFA). Some studies of pathologic subtypes have also suggested specific atrophy patterns; however, results are inconsistent. Our aim was to test the hypothesis that clinical, but not pathologic, classification (FTD with ubiquitin inclusions [FTD-U] and FTD with tau inclusions [FTD-T]) is associated with predictable patterns of regional atrophy.


METHODS
Magnetic resonance scans of nine FTD-U and six FTD-T patients (histologically confirmed) were compared with 25 controls using voxel-based morphometry (VBM). Analyses were conducted with the patient group classified according to histologic or clinical variant. Additionally, three Alzheimer pathology patients who had the syndrome of SEMD in life (FTD-A) were analyzed.


RESULTS
The VBM studies in clinical variants confirmed established patterns of atrophy (SEMD, rostral temporal; bvFTD, mesial frontal; PNFA, left insula). FTD-U and FTD-T VBM results were very similar, showing severe atrophy in the temporal poles, mesial frontal lobe, and insulae. A conjunction analysis confirmed this similarity. Subgroup analysis found that SEMD associated with either FTD-T or FTD-U was associated with similar rostral temporal atrophy; however, FTD-A had a qualitatively different pattern of left hippocampal atrophy.


CONCLUSIONS
While there is predictable atrophy for clinical variants of frontotemporal dementia (FTD), histologic FTD variants show no noticeable differences. Reports of specific atrophy profiles are likely the result of idiosyncrasies in small groups. Semantic dementia associated with Alzheimer pathology, however, presented a distinct atrophy pattern.
Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Cambridge, UK.
J M S
JM
Pereira
G B
GB
Williams
J
J
Acosta-Cabronero
G
G
Pengas
M G
MG
Spillantini
J H
JH
Xuereb
J R
JR
Hodges
P J
PJ
Nestor
D000368:Aged; D018888:Aphasia, Primary Progressive / Q000473:pathology / Q000503:physiopathology; D001284:Atrophy / Q000145:classification / Q000209:etiology / Q000473:pathology*; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology; D003704:Dementia / Q000145:classification / Q000473:pathology* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D002479:Inclusion Bodies / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D013702:Temporal Lobe / Q000473:pathology / Q000503:physiopathology