Apathy, Functional Impairment More Likely in Frontotemporal Dementia

In patients with behavioral variant frontal temporal lobe dementia (bvFTD), the need exists for a more comprehensive evaluation of noncognitive symptoms, such as apathy, with functional impairment shown to be a key outcome, according to a research letter published in the journal JAMA Network Open.

Recognizing that apathy, which is common among individuals with bvFTD, can have a profound impact on mortality, morbidity, and caregiver burden among patients with bvFTD, researchers sought to explore the association between apathy and function longitudinally across dementia severity. They used data from patients who were enrolled in the National Institute of Aging–funded Alzheimer’s Disease Research Centers.

Study participants included those with a clinical diagnosis of bvFTD at baseline who were enrolled in the National Alzheimer’s Coordinating Center Uniform Data Set (NACC-UDS) between September 2005 and December 2019 with ≥1 annual follow-up visit. All data obtained were analyzed between January 5, 2022, and October 5, 2022.

Function was measured with the use of the Functional Assessment Questionnaire (FAQ). Apathy was evaluated via use of clinician judgment within the NACC-UDS protocol, based on all available information, which included a clinical evaluation, and review of medical records.

All participants were classified into 4 mutually exclusive apathy groups: (1) never, (2) intermittent, (3) persistent, and (4) always. Severity of dementia was categorized by baseline Clinical Dementia Rating (CDR) scale of 0.5+, 1, and ≥2.

A total of 866 patients were included in the analysis. The researchers found worse baseline FAQ scores among participants with more severe dementia. When compared with individuals with a CDR of 0.5+, FAQ scores were 8.3±0.7 points higher (ie, worse) among those with a CDR of 1 and 19.9±1.0 points higher among those with a CDR of ≥2 (P <.001 for both).

In the entire sample, FAQ scores worsened by 4.4±0.3 points annually (P <.001). Rate of functional decline was slower among participants with a baseline CDR of 1 and a baseline CDR of ≥2 (P <.001 for both), compared with those with a baseline CDR of 0.5+, which suggested a plateauing effect.

Additionally, compared with the never-apathetic group, FAQ scores were 3.5±0.9 points higher at baseline in the intermittent-apathetic group and the persistent-apathetic group, and 5.1±0.9 points higher at baseline in the always-apathetic group (P <.001 for both). Rate of functional decline was more rapid in the always-apathetic group, as well as in the intermittent-apathetic and the persistent-apathetic groups (P <.001 for both), compared with the never-apathetic group.

A key limitation of the study is the fact that the research sample may not be representative of the more typical patient populations seen in clinical settings.

The researchers noted that the results of their study “…raise awareness of the need for more comprehensive diagnostic assessment of noncognitive symptoms, such as apathy, in patients with bvFTD. Research on AD [Alzheimer disease] has identified interventions that may improve apathy.”

Furthermore, they acknowledged, “Findings from this study highlight the need to develop early differential interventions for apathy tailored for bvFTD and suggest function as a key study outcome.”

Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.