Inappropriate trusting behaviour in dementia

Abstract

Background: Inappropriate trusting behaviour may have significant social, financial and other consequences for people living with dementia. However, its clinical associations and predictors have not been clarified. Here we addressed this issue in canonical syndromes of frontotemporal dementia (FTD) and Alzheimer's disease (AD).

Methods: In 34 patients with AD and 73 with FTD (27 behavioural variant (bv)FTD, 22 semantic variant primary progressive aphasia (svPPA), 24 nonfluent/agrammatic variant (nfv)PPA) we recorded inappropriate trusting and other abnormal socio-emotional behaviours using a semi-structured caregiver survey. Patients were comprehensively characterised using a general cognitive assessment and the Revised Self-Monitoring Scale (RSMS; an informant index of socioemotional awareness).

Results: Inappropriate trusting was more frequent in svPPA (55%) and bvFTD (44%) than nfvPPA (17%) or AD (24%). After adjusting for age, sex, education and Mini-Mental State Examination (MMSE) score, inappropriate trusting was significantly more likely in svPPA (odds ratio 3.61; 95% confidence interval 1.41-8.75) and bvFTD (3.01, 1.23-6.65) than AD. Significant predictors of inappropriate trusting comprised apathy in svPPA, disinhibition and altered pain responsiveness in bvFTD, and lower MMSE and RSMS (self-presentation) scores in AD.

Conclusion: Dementia syndromes vary in prevalence and predictors of abnormal trusting behaviour, with implications for clinical counselling and safeguarding.

Keywords: Alzheimer’s disease; dementia; frontotemporal dementia; primary progressive aphasia; trust.

Figure 1

Risk factors for inappropriate trusting behaviour in dementia syndromes. The figure is a graphical representation of diagnostic, cognitive and behavioural risk factors for inappropriate trusting behaviour in patients with dementia (see Supplementary Table S2). Odds ratios (with 95% confidence intervals) are shown, plotted on a log-10 scale; significantly increased or reduced odds are depicted in red. The left panel displays the risk associated with a diagnosis of each canonical frontotemporal dementia syndrome relative to Alzheimer’s disease (adjusted for age, sex, years of education, and Mini-Mental State Examination score; see text). The right panel displays the risk associated with key cognitive and behavioural factors within each diagnostic group (excluding the nfvPPA group, as only four patients with this diagnosis showed inappropriate trusting). AD, patient group with Alzheimer’s disease; bvFTD, patient group with behavioural variant frontotemporal dementia; EX, sensitivity to socio-emotional expressiveness; MMSE nfvPPA, patient group with non-fluent/agrammatic primary progressive aphasia; MMSE, Mini-Mental State Examination score; RSMS, Revised Self-Monitoring Scale; SP, ability to modify self-presentation; svPPA, patient group with semantic variant primary progressive aphasia; WASI, Wechsler Abbreviated Scale of Intelligence.