Behavioral-variant frontotemporal dementia: Distinct phenotypes with unique functional profiles.

OBJECTIVE: To identify distinct behavioral phenotypes of behavioral-variant frontotemporal dementia (bvFTD) and to elucidate differences in functional, neuroimaging, and progression to residential care placement. METHODS: Eighty-eight patients with bvFTD were included in a cluster analysis applying levels of disinhibition and apathy (Cambridge Behavioural Inventory-Revised) to identify phenotypic subgroups. Between-group (Kruskal-Wallis, Mann-Whitney U) functional differences (Disability Assessment for Dementia) and time to residential care placement (survival analyses) were examined. Cortical thickness differences (whole-brain MRI) were analyzed in patients with bvFTD vs healthy controls (n = 30) and between phenotypic subgroups. RESULTS: Four phenotypic subgroups were identified: primary severe apathy (n = 26), severe apathy and disinhibition (n = 26), mild apathy and disinhibition (n = 27), and primary severe disinhibition (n = 9). Patients with severely apathetic phenotypes were more functionally impaired and had more extensive brain atrophy than those with mild apathy or severe disinhibition alone. Further imaging analyses indicated that the right middle temporal region is critical for the development of disinhibition, an association that remains with disease progression and in the context of severe apathy. Finally, no difference in time to residential care admission was found between phenotypes. CONCLUSIONS: This study reveals that different clinical behavioral phenotypes of bvFTD have differing profiles of functional decline and distinct patterns of associated cortical changes. These findings emphasize the importance of apathy in functional impairment, highlight the role of the right temporal region in disinhibition, and suggest that disability may be a sensitive outcome measure for treatments targeting reduction of apathy. These phenotypes could also support understanding of prognosis and clinical management.

Cognitive and Behavioral Symptoms in ALSFTD: Detection, Differentiation, and Progression.

Brief screening tools that detect and differentiate patients with amyotrophic lateral sclerosis and frontotemporal dementia (ALSFTD) from those more subtle cognitive or behavioral symptoms (ALS plus) and motor symptoms only (ALS pure) is pertinent in a clinical setting. The utility of 2 validated and data-driven tests (Mini-Addenbrooke's Cognitive Examination [M-ACE] and Motor Neuron Disease Behavioral Scale [MiND-B]) was investigated in 70 ALS patients (24 ALSFTD, 19 ALS plus, and 27 ALS pure). More than 90% of patients with ALSFTD scored at or below the cutoff on the M-ACE, whereas this was seen in only about 20% of ALS patients without dementia. The MiND-B differentiated between ALS pure and ALS plus diagnostic categories. Rasch modeling of M-ACE and MiND-B items revealed early cognitive (fluency, memory recall) and behavioral (apathy) symptoms in ALSFTD. The combined use of the M-ACE and MiND-B detects patients with ALSFTD, differentiates along the ALS continuum, and offers insight into the progression of nonmotor symptomatology in ALSFTD.

When one loses empathy: its effect on carers of patients with dementia.

The effects of empathy loss in frontotemporal dementia (FTD) and Alzheimer disease (AD) on carer symptomatology were investigated. Carers of patients with 2 clinical subtypes of FTD (behavioral-variant FTD [bvFTD] = 18; semantic dementia [SD] = 14) and AD (n = 18) completed the Interpersonal Reactivity Index (IRI), a standardized questionnaire of empathy as well as a measure of perceived burden (Zarit Burden Interview) and the quality of the marital relationship (Intimate Bond Measure). Patient ratings were also obtained on the IRI. Loss of empathy was most striking in the bvFTD group with a marked discrepancy observed between carer and patient ratings for change in emotional warmth and the ability to take the perspective of others. Empathy loss in bvFTD was associated with a loss of a caring marital relationship. Empathic deficits in SD were milder by comparison to bvFTD and correlated with disease severity and increased perceived carer burden. The behavioral pattern observed in AD differed from the FTD syndromes; deficits were observed only for measures of personal distress with carers reporting that patients were less able to handle emotionally evocative situations. Results highlight that changes in aspects of empathy differ across dementia syndromes and are associated with differing carer and clinical variables. These findings might be explained by the progression of atrophy in regions that are known to be critical for empathy and social behavior and has implications for the delivery and planning of services in dementia.