Neuroimaging correlates of everyday action in dementia

Abstract

The everyday, functional impairments associated with dementia remain poorly understood from a neuropsychological perspective. This study investigated relations between brain structure volumes and two measures of everyday action—caregiver questionnaire and direct assessment—in 57 participants with dementia. Results showed that caregiver ratings reflecting more functional impairment were strongly associated with smaller volumes of deep white matter. Direct assessment of everyday task performance in a subsample revealed relations between unique neurological substrates and discrete everyday action error types. Findings emphasize differences in functional assessment methods and highlight the role of white matter in functional deficits in dementia.

• Dementia
• Everyday action
• Executive control
• Episodic memory
• White matter alterations

Acknowledgements: We sincerely thank the patients who provided data for this investigation, as well as the funding agencies that provide author time as well as funds for securing leukoaraiosis (LA) and white matter segmentation assistance. We acknowledge Stephen Towler, University of Florida, for his development of the ImageJ macro and employment of freeware for LA and white matter segmentation, as well as Sena Moran, for her assistance with hippocampal volumes and rater reliability.

Funding: This study was partially supported by the National Institute of Neurological Disorders and Stroke (NINDS) [grant number K23NS60660] (C.P.) and the Alzheimer’s Association [grant number IIRG0627542] (D.J.L.).

Notes

3. ¹The term “action addition errors” also has been used to refer to off-task commissions.

4. ²MMSE was comparably associated with both omission errors (r = −.41, p < .05) and commission errors (r = −.48, p < .05); therefore, the different pattern of relations to neuroimaging variables between these error types cannot be explained by the possibility that one error type is more or less strongly associated with gross dementia severity.

5. ³MMSE was significantly and strongly associated with on-task commissions (r = .52, p < .05), but was not significantly associated with off-task commissions (r = −.11). As mentioned earlier in the paper, MMSE was associated with only one of the neuroimaging variables—hippocampus (r = .25, p = .06). Therefore, to examine whether the different relations between on-task/off-task commissions and the hippocampus may be explained by gross dementia severity, partial correlations (controlling for MMSE) were performed. These results did not meaningfully change the pattern of findings reported in Table 8 (On-Task Commissions × Hippocampus: r_p = −.03; Off-Task Commissions × Hippocampus: r_p = −.37, p = .05).