1 Department of Neurology, N.R.S. Medical College and Hospital, Kolkata, West Bengal, India.
2 Department of Neurology, University Hospital "12 de Octubre", Madrid, Spain; Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain; Department of Medicine, Faculty of Medicine, Complutense University, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre (Imas12), Madrid, Spain. Electronic address: [email protected].