Structural brain changes in people with dementia receiving Cognitive Stimulation Therapy: Preliminary findings

There are growing numbers of people with dementia (PwD) globally, a syndrome with well documented impact on brain structure and connectivity that lead to cognitive impairment. Cognitive Stimulation Therapy (CST) is a non-pharmacological intervention for dementia with a strong evidence-base indicating positive effects on cognition and mood. There is, however, a lack of data on the effects of CST on brain structural and functional changes. This study aimed to analyze the impact of CST on brain cortical differences through the symmetrized percentage change (SPC) of surface area, thickness and volume measured through magnetic resonance imaging (MRI).

Structural MRI was collected from 17 PwD who received CST and 11 treatment as usual (TAU) controls pre- and pos-intervention. The SPC of cortical structure was calculated for each participant. Freesurfer's general linear model was used, and the resulting statistical maps were thresholded at p < .01. The maps were then corrected for multiple comparisons using Monte Carlo Z simulation with 10.000 iterations. The family wise error cluster-level correction for multiple comparisons threshold was set at p < .05 and p-values were further corrected using the Bonferroni method to correct for both hemispheres.

There were no statistically significant differences between CST and TAU groups regarding age, sex or years of education. Relative to TAU, the CST group exhibited a decrease in surface area in the left rostral middle frontal region (P_FWE = 0.019, Cohen's δ of 1.764), in addition to an increase in thickness in the right supramarginal (P_FWE = 0.012, Cohen's δ of -2.063) and postcentral regions (P_FWE = 0.038, Cohen's δ of -2.11). No differences in volume SPC were found between groups. A statistically significant correlation was also found between cognition and the right supramarginal gyrus thickness (p = .017).

This is the first study on the effects of CST on brain surface area, thickness, and volume. Our results indicate a change in cortical structure associated with CST. Reduced cortical thickness in the rostral middle frontal region may be related to the effects of CST on mood and stress. Increased thickness in the right supramarginal and postcentral regions may be due to increased abilities of phonological processing, verbal working memory, and somatosensory processing. More data, with larger samples, are needed to support these findings.