Understanding the underpinnings of the frontotemporal lobar degeneration: evidence for benign and malignant forms.
BACKGROUND
Frontotemporal lobar degeneration (FTLD) encompasses different clinical subtypes but with overlapping features. Establishing whether FTLD represents a continuum or recognizes distinct subgroups may be crucial for diagnostic purposes and therapeutic approaches.


OBJECTIVE
To investigate whether cognitive profiles in a large sample of FTLD patients reflect qualitatively distinct subtypes, variants along a single continuum of severity, or severity differences within subtypes.


METHODS
Latent class analysis (LCA), exploratory factor analysis (FA), and mixture factor analysis (MFA) modeling were applied to a wide neuropsychological assessment data. LCA corresponds to qualitatively distinct subtypes, FA corresponds to quantitatively severity differences, and MFA allows for both subtypes and severity differences within subtypes.


RESULTS
The authors consecutively enrolled 314 FTLD patients. A comparison of the different models shows that MFA models provided a superior fit to the data than any of the LCA or exploratory FA models. The "best" MFA model was defined by two continuous variables evaluating the disease severity within two groups of patients ("good" and "bad" performers). These two populations have been called "benign" and "malignant" FTLD.


CONCLUSIONS
FTLD recognizes distinct subgroups beyond the disease severity, namely a benign form and a more malignant form. This observation needs to be taken into account in future clinical trials and for therapeutic approaches.
Borroni
Barbara
B
Centre for Aging Brain and Neurology Disorders, Neurology, University of Brescia, Italy. bborroni@inwind.it
Grassi
Mario
M
Agosti
Chiara
C
Bellelli
Giuseppe
G
Padovani
Alessandro
A
D000368:Aged; D035841:Behavioral Research / Q000295:instrumentation / Q000379:methods / Q000592:standards; D003071:Cognition; D003704:Dementia / Q000175:diagnosis* / Q000473:pathology; D005163:Factor Analysis, Statistical; D005240:Feasibility Studies; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D057174:Frontotemporal Lobar Degeneration / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000592:standards / Q000706:statistics & numerical data; D012720:Severity of Illness Index; D013702:Temporal Lobe / Q000473:pathology