Demographic changes in a large motor neuron disease cohort in Portugal: a 27 year experience.

: Motor Neuron Diseases (MND) have a large clinical spectrum, being the most common amyotrophic lateral sclerosis (ALS) but there is significant clinical heterogeneity. Our goal was to investigate this heterogeneity and any potential changes during a long period. : We performed a retrospective cohort study among a large Portuguese cohort of MND patients ( = 1550) and investigated changing patterns in clinical and demographic characteristics over the 27-year period of our database. With that aim, patients were divided into three 9-year groups according to the date of their first visit to our unit: P1, 1994-2002; P2, 2003-2011; P3, 2012-2020. : The overall cohort's clinical and demographic characteristics are consistent with clinical experience, but our findings point to gradual changes over time. Time pattern analysis revealed statistically significant differences in the distribution of clinical phenotypes, the average age of onset, diagnostic delay, the proportin of patients using respiratory support with noninvasive ventilation (NIV), time to NIV, and survival. Across time, in the overall cohort, we found an increasing age at onset ( = 0.029), a decrease of two months in diagnostic delay ( 0.001) and a higher relative frequency of progressive muscular atrophy patients. For ALS patients with spinal onset, from P1 to P2, there was a more widespread (54.8% vs 69.4%,  = 0.005) and earlier (36.9 vs 27.2 months,  0.05) use of NIV and a noteworthy 13-month increase in median survival ( = 0.041). : Our results probably reflect better comprehensive care, and they are relevant for future studies exploring the impact of new treatments on ALS patients.