Analyses of n-back high-load working memory in early Parkinson's disease: An fMRI study

Cognitive impairment is common in Parkinson's disease (PD). Working memory is a group of basic processes that is part of many cognitive operations (from complex decision-making to selective attention). To date, there is not sufficient research on working memory impairment in early PD patients, especially patients under high load.

The aim of this study was to observe the activation of brain regions in early PD patients during verbal high-load cognitive tasks and to explore the correlation between cognitive behavior indexes and gray matter areas of brain structure.

A total of 45 participants were included: 15 healthy controls and 30 PD patients without dementia. They underwent BOLD imaging during a digital N-back working memory task in a 3 T scanner, and their high-resolution T1-weighted three-dimensional brain anatomical images were collected. The SPM12 standard method was used to generate a comparison map with 2 plus 3-back greater than 0-back, and with age, sex, levodopa equivalent daily dose (LEDD) and education as covariables, and multiple regression analysis was conducted to analyze the correlation between MOCA, MES and brain gray matter volume.

Compared with the control group, the frontoparietal region was significantly activated in patients with PD under the background of high working memory burden. In addition, there was a widespread area correlation between the brain structure and basic cognitive function.

The frontoparietal cortex is the core hub of working memory, and there may be a compensation mechanism in PD patients without dementia with a high-load of working memory.