Does cognitive performance decline as a function of age at onset in Parkinson's disease? the role of age at assessment, education, and clinical severity.

Morales-de-Arcia AA Lázaro-Figueroa A Caballero-Sánchez U De-Anda-Moctezuma G Hernández-Ruiz I Reyes-Pérez P Esquivias-Farías JM Guerra-Galicia CM Morelos-Figaredo E Estrada-Bellmann I Trejo-Ayala R Salinas-Barboza K Matuk Y Gandarilla-Martínez NA Oropeza D López-Pintor A Nolasco-López M Angulo-Arrieta AP Zayas-Del Moral A Medina-Rivera A Alcauter S Rentería M Ruiz-Contreras AE Mexican Parkinsons Research Network (MEX-PD)