Ventromedial-frontopoloar prefrontal cortex atrophy correlates with insight loss in frontotemporal dementia Alzheimer's disease

Hornberger, Michael, Yew, Belinda, Gilardoni, Silvia, Mioshi, Eneida, Gleichgerrcht, Ezequiel, Manes, Facundo and Hodges, John R. (2014) Ventromedial-frontopoloar prefrontal cortex atrophy correlates with insight loss in frontotemporal dementia Alzheimer's disease. Human Brain Mapping, 35 (2), 367 - 733. (doi:10.1002/hbm.22200).

Abstract

Encoding information in reference to the self enhances subsequent memory for the source of this information. In healthy adults, self-referential processing has been proposed to be mediated by the cortical midline structures (CMS), with functional differentiation between anterior-ventral, anterior-dorsal and posterior regions. While both Alzheimer's disease (AD) and behavioural-variant frontotemporal dementia (bvFTD) patients show source memory impairment, it remains unclear whether they show a typical memory advantage for self-referenced materials. We also sought to identify the neural correlates of this so-called ‘self-reference effect’ (SRE) in these patient groups. The SRE paradigm was tested in AD (n = 16) and bvFTD (n = 22) patients and age-matched healthy controls (n = 17). In this task, participants studied pictures of common objects paired with one of two background scenes (sources) under self-reference or other-reference encoding instructions, followed by an item and source recognition memory test. Voxel-based morphometry was used to investigate correlations between SRE measures and regions of grey matter atrophy in the CMS. The behavioural results indicated that self-referential encoding did not ameliorate the significant source memory impairments in AD and bvFTD patients. Furthermore, the reduced benefit of self-referential relative to other-referential encoding was not related to general episodic memory deficits. Our imaging findings revealed that reductions in the SRE were associated with atrophy in the anterior-dorsal CMS across both patient groups, with additional involvement of the posterior CMS in AD and anterior-ventral CMS in bvFTD. These findings suggest that although the SRE is comparably reduced in AD and bvFTD, this arises due to impairments in different subcomponents of self-referential processing.

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Contributors

Author: Michael Hornberger

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