Understanding the Underpinnings of the Frontotemporal Lobar Degeneration: Evidence for Benign and Malignant Forms

• Published in: The American journal of geriatric psychiatry 2010-09, Vol.18 (9), p.830-838
• Main Authors: Borroni, Barbara, M.D, Grassi, Mario, Ph.D, Agosti, Chiara, M.D, Bellelli, Giuseppe, M.D, Padovani, Alessandro, M.D., Ph.D
• Format: Article
• Language: English
• Subjects: Aged; Behavioral Research - instrumentation; Behavioral Research - methods; Behavioral Research - standards; benign variant; Cognition; Dementia - diagnosis; Dementia - pathology; exploratory factor analysis (FA); Factor Analysis, Statistical; Feasibility Studies; Female; Frontal Lobe - pathology; Frontotemporal lobar degeneration; Frontotemporal Lobar Degeneration - diagnosis; Frontotemporal Lobar Degeneration - epidemiology; Frontotemporal Lobar Degeneration - pathology; Humans; Internal Medicine; Italy; latent class analysis (LCA); Male; Middle Aged; mixture factor analysis (MFA); Neuropsychological Tests - standards; Neuropsychological Tests - statistics & numerical data; Severity of Illness Index; Temporal Lobe - pathology
• ISSN: 1064-7481; 1545-7214
• DOI: 10.1097/JGP.0b013e3181d14595

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. Method 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.