Profiles of motivational impairment and their relationship to functional decline in frontotemporal dementia

Motivational disturbances are pervasive in frontotemporal dementia (FTD) and impact negatively on everyday functioning. Despite mounting evidence of anhedonia in FTD, it remains unclear how such changes fit within the broader motivational symptom profile of FTD, or how anhedonia relates to functional outcomes. Here we sought to comprehensively characterize motivational disturbances in FTD and their respective relationships with functional impairment. A cross-sectional study design was used including 211 participants-68 behavioral-variant FTD (bvFTD), 32 semantic dementia (SD), 43 Alzheimer's disease (AD), and 68 healthy older control participants. Anhedonia severity was measured using the Snaith-Hamilton Pleasure Scale while severity of apathy was assessed across Emotional, Executive, and Initiation dimensions using the Dimensional Apathy Scale. Functional impairment was established using the FTD Functional Rating Scale (FRS). Distinct motivational profiles emerged in each dementia syndrome: a domain-general motivational impairment in bvFTD; a predominantly anhedonic profile in SD; and more pronounced initiation and executive apathy in AD. Correlation analyses revealed differential associations between motivational symptoms and severity of functional impairment in each group. Executive apathy was associated with functional impairment in bvFTD, while anhedonia was strongly correlated with functional decline in SD. Finally, executive and emotional apathy were associated with functional decline in AD. Our study indicates distinct profiles of apathy and anhedonia in FTD syndromes, which in turn are differentially associated with functional decline. This detailed characterization of motivational phenotypes can inform patient stratification for targeted interventions to improve functional outcomes.

Clinico-demographics of people with younger-onset dementia and neuropsychiatric symptoms referred to an Australian dementia support service: A comparison study with older-onset dementia

OBJECTIVE

Younger-onset dementia accounts for about 5-10% of all dementias in Australia. Little data is available on neuropsychiatric symptoms in people with younger-onset dementia compared to those with older-onset dementia. This study aims to compare the types of neuropsychiatric symptoms and their clinico-demographic characteristics of people with younger-onset dementia and older-onset dementia who are referred to a specific dementia support service.

METHODS

A 2-year retrospective observational cross-sectional analysis was undertaken on referrals with neuropsychiatric symptoms from Dementia Support Australia programmes. Neuropsychiatric symptoms were measured using the Neuropsychiatric Inventory total severity scores and distress scores. Contributing factors to neuropsychiatric symptoms for dementia groups were examined. Logistic regression was used to examine the relationship between individual neuropsychiatric symptoms and having older-onset dementia vs younger-onset dementia.

RESULTS

Of the 15,952 referrals, about 5% (n = 729, mean age: 60.7 years, standard deviation = 5.4) were individuals with younger-onset dementia. Referrals with older-onset dementia were more likely to be female (56%), whereas referrals with younger-onset dementia were more likely to be male (54%). There was a four times greater rate of frontotemporal dementia for those with younger-onset dementia (16.0%, n = 117) compared to those with older-onset dementia (2.8%, n = 427), χ² (1) = 366.2, p < 0.001. Referrals with younger-onset dementia were more likely to be referred from community settings and those with older-onset dementia were more likely to be from residential aged care. Overall, there was no difference in the severity and distress of neuropsychiatric symptoms between the two groups. Contributing factors to neuropsychiatric symptoms were different between the groups, with pain being more frequently endorsed for individuals with older-onset dementia whereas communication difficulties were more commonly identified for those with younger-onset dementia.

CONCLUSION

Clinico-demographics of referrals with younger-onset dementia differ from those with older-onset dementia. There were some differences in the characteristics of neuropsychiatric symptoms between younger-onset dementia and older-onset dementia. Our findings have implications for service provision and support for people with dementia at different ages.

Cerebrospinal fluid neurofilament light predicts the rate of executive function decline in younger-onset dementia

INTRODUCTION

Determining disease severity and predicting prognosis in younger onset-dementia (YOD) remains challenging. Whether CSF biomarkers neurofilament light (NfL), tau and amyloidβ 42 (Aβ42) can help provide such information has been underexplored.

METHODS

Patients with YOD and CSF analysis were identified. We compared baseline NfL, tau and Aβ42 concentrations with contemporaneous Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG) scores to assess their association with severity of cognitive impairment. Cognitive decline, as measured by longitudinal NUCOG assessment, was correlated against baseline biomarker levels to assess their utility in predicting the rate of cognitive decline.

RESULTS

78 patients with YOD (mean age = 56 years, SD = 8) and CSF analysis were identified. Dementia types included Alzheimer's disease, behavioural variant frontotemporal dementia, dementia not-otherwise-specified and other. Tau was associated with contemporaneous memory dysfunction (r = -0.556, 95% CI:[-0.702,-0.393], p < .001). 21 patients had longitudinal cognitive assessment up to 82 months from CSF sampling. NfL was associated with the rate of executive function decline (r = 0.755, 95% CI:[0.259,0.937], p < .001). Aβ42 was associated with the rate of memory decline (r = -0.582, 95% CI:[-0.855,-0.274], p = .007) and rate of total NUCOG decline (r = -0.515, 95% CI: [-0.809, -0.227], p = .017).

CONCLUSION

CSF tau is related to contemporaneous memory impairment in YOD. NfL and Aβ42 levels are associated with the rate of executive function and memory decline, respectively, and may have a role in prognostication in YOD.