Frontiers in Neuroscience (Jul 2014)

Longitudinal changes in task-evoked brain responses in Parkinson’s disease patients with and without mild cognitive impairment

  • Urban eEkman,
  • Johan eEriksson,
  • Lars eForsgren,
  • Magdalena Eriksson Domellöf,
  • Eva eElgh,
  • Anders eLundquist,
  • Lars eNyberg

DOI
https://doi.org/10.3389/fnins.2014.00207
Journal volume & issue
Vol. 8

Abstract

Read online

Cognitive deficits are common in Parkinson’s disease. Previous cross-sectional research has demonstrated a link between cognitive impairments and fronto-striatal dopaminergic dysmodulation. However, longitudinal studies that link disease progression with altered task-evoked brain activity are lacking. Therefore, our objective was to longitudinally evaluate working-memory related brain activity changes in Parkinson’s disease patients with and without mild cognitive impairment.Patients were recruited within a longitudinal cohort study of incident patients with idiopathic parkinsonism. We longitudinally (at baseline examination and at 12-months follow-up) compared 28 patients with Parkinson’s disease without mild cognitive impairment with 11 patients with Parkinson’s disease and mild cognitive impairment. Functional MRI blood oxygen level dependent signal was measured during a verbal two-back working-memory task. Patients with mild cognitive impairment under-recruited bilateral medial prefrontal cortex, right putamen, and lateral parietal cortex at both time-points (main effect of group: p<0.001, uncorrected). Critically, a significant group-by-time interaction effect (p<0.001, uncorrected) was found in the right fusiform gyrus, indicating that working-memory related activity decreased for patients with Parkinson’s disease and mild cognitive impairment between baseline and follow-up, while patients without mild cognitive impairment were stable across time-points. The functional connectivity between right fusiform gyrus and bilateral caudate nucleus was stronger for patients without MCI relative to patients with MCI.Our findings support the view that deficits in working-memory updating are related to persistent fronto-striatal under-recruitments in patients with early phase Parkinson’s disease and mild cognitive impairment. The longitudinal evolution of mild cognitive impairment in Parkinson’s disease translates into additional task-evoked posterior cortical changes.

Keywords