The cohort consists of 1171 PD patients followed longitudinally for more than 20 years. Clinical, cognitive (MoCA score) and genetic testing were performed. By the end of May 2018, 484 patients have died.

Of the patients, 84% had developed MoCA scores below 26 within the first 15 years of the disease, while 16 % had normal MoCA scores.

Kaplan-Meier survival estimates, based on age at disease onset ( AAO) categories, show statistically significant difference in the median survival time in AAO 20-39, 40-59, 60-69, 70-79 and 80 plus, respectively 33, 20, 14, 10 and 9 years.

Kaplan- Meier survival estimates, based on MoCA scores at 5 year, 10 year and 15 year, show a statistically significant difference in the median survival time in patients with MoCA scores below 26 compared to those with normal MoCA scores, respectively 5 versus 12 years, 4 versus 10 years and 4 versus 11 years.

Early onset PD patients had the longest median survival time. However, when MoCA score drops below 26, there is a statistically significant shortening in median survival time compared to those with normal MoCA scores, confirming that cognitive function is a good indicator for survival in Parkinson Disease.