Progression of Parkinson's disease patients' subtypes based on cortical thinning: 4-year follow-up

Three cortical atrophy patterns were previously identified in non-demented Parkinson's disease patients using a data-driven approach based on cortical thickness data: i) parieto-temporal pattern of atrophy with worse cognitive performance (pattern 1), ii) occipital and frontal cortical atrophy with younger disease onset (pattern 2), and iii) non-detectable cortical atrophy (pattern 3). We aimed to investigate the evolution of these three patterns over time.

Magnetic resonance imaging and neuropsychological assessment were obtained at baseline and follow-up (3.8 ± 0.4 year apart) in a group of 45 Parkinson's disease patients and 22 healthy controls. FreeSurfer was used for cortical thickness analysis and global atrophy measures.

Temporo-parietal cortical thinning occurred in pattern 2, 3 and controls groups, and patients showed decline in processing speed (as measured by the Stroop Word-Color test, the Symbol Digits Modalities test and the Trail Making Test Part B) and in semantic fluency (animals). Pattern 3 patients showed more progressive cortical thinning in the left prefrontal cortex than controls and more right occipital thinning than pattern 2 patients over time. Pattern 1 patients had greater compromise in activities of the daily living and suffered higher attrition rate.

The Parkinson's disease phenotypes identified using cluster analysis of cortical thickness data showed different progression over time. The presence of prefrontal thinning and younger disease onset at baseline was associated to less cortical degeneration, while non-atrophic patients progressed showing a temporo-parietal cortical thinning.