The functional anatomy of working memory training using chunking in Alzheimer's disease

Abstract

AIMS A randomised controlled trial of a novel cognitive training regime based on chunking was conducted in participants with early Alzheimer’s Disease. Functional neuroimaging was performed to examine re-organisation of brain activity following cognitive training. The study tested the following hypotheses: 1) Training individuals with early AD in the use of chunking strategies would improve their working memory (WM) capacity. 2) Following training in chunking, improvement in WM capacity would generalise across different modalities of WM tasks and measures of general cognitive functioning. 3) Improvement in WM capacity following cognitive training would be associated with re-organisation of functional activity in the prefrontal cortex (PFC) and posterior parietal cortex (PPC). METHODS 30 patients with early AD were recruited and assessed on WM and general cognitive tasks. They also performed a verbal WM chunking task whilst undergoing fMRI. They were then randomised to either an active control group or cognitive training group. The cognitive training group had 18 sessions of adaptive WM training using chunking strategies, whilst the control subjects practised a non adaptive WM task. All subjects were then reassessed using the same measures of cognitive function, WM and fMRI protocol, allowing the above hypotheses to be tested. RESULTS At baseline, all participants benefitted from chunking to improve WM (p < 0.001). Following training, the training group demonstrated a significant improvement on the chunking WM task (p < 0.05) compared with the control group. There were also significant improvements in measures of general cognitive function (MMSE and ADAS-Cog) and verbal episodic memory in the training group compared to controls (p < 0.05). Training was significantly associated with a reduction in activation in the PFC-PPC network following cognitive training. DISCUSSION The impact of this novel approach to improving WM in early AD is discussed, in the context of existing knowledge of cognitive training and functional plasticity in AD.

Date of Award	2014
Original language	English
Awarding Institution	King's College London
Supervisor	Robert Howard (Supervisor) & A Owen (Supervisor)