Focal Brain Atrophy Predicts Cognitive Decline in Parkinson Disease After DBS

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An association was found between the variation of the backward digit-span task and the thickness of the right and left superior frontal gyrus.
An association was found between the variation of the backward digit-span task and the thickness of the right and left superior frontal gyrus.

Focal brain atrophy as measured by magnetic resonance imaging (MRI) holds potential prognostic value for predicting the risk for cognitive decline in patients with Parkinson disease (PD) who have undergone deep brain stimulation (DBS) of the subthalamic nucleus (STN), according to a study published in Brain Structure & Function.

A total of 42 consecutive patients with PD who underwent STN-DBS were enrolled in this study. Preoperative T1-weighted MRI was used to assess normalized brain structure volumes and cortical thickness at baseline. The Mini Mental State Examination, Frontal Assessment Battery at Bedside, forward and backward digit-span task, and Mattis Dementia Rating Scale assessments were used to test for cognitive performance before and 1 year after surgery.

In the multivariate analyses, which controlled for age, sex, baseline disease severity, and decreases in cumulative L-Dopa equivalent daily dose after surgery, there was a significant association between the variation of total Mattis Dementia Rating Scale and the volume of the left lateral ventricle (β, −5.73; P =.032). In addition, investigators observed a significant correlation between the variation of the initiation/perseveration subscore, as well as the volume of the left nucleus accumbens (β, 1400.6; P =.042) and the volume of the left lateral ventricle (β, −13.21; P =.017).

Another association was found between the variation of the backward digit-span task and the thickness of the right and left superior frontal gyrus (β, 3.12 [P =.004] and β, 2.99 [P =.007], respectively). The preoperative volume of the left nucleus accumbens provided significant predictive value for postoperative reductions in the initiation/attention subscore (area under the curve, 0.92 [P <.001]; 96.3% sensitivity, 80.0% specificity, 92.9% positive predictive value, and 92.9% negative predictive value).

The lack of a non-DBS control group limited the researchers' ability to determine whether nucleus accumbens atrophy would correlate with cognitive decline in the absence of surgical intervention.

Findings from this study offer "new clinical perspectives for identifying more suitable candidates for STN-DBS," given the greater access to fully automated brain segmentation applications in the clinical space.

Reference

Planche V, Munsch F, Pereira B, et al. Anatomical predictors of cognitive decline after subthalamic stimulation in Parkinson's disease [published online May 7, 2018]. Brain Struct Funct. doi: 10.1007/s00429-018-1677-2

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