| Popis: |
Amyotrophic lateral sclerosis (ALS) is a progressive debilitating disease of the upper and lower motor neurons. Median survival of ALS patients is consistently estimated at between 2-3 years from symptom onset, with some evidence that survival is increasing due to improved care. There are few well-established risk factors for ALS, and there is conflicting evidence regarding the trends in ALS incidence and mortality over the past several decades. In Chapter I we investigate the trends in ALS incidence and mortality in Denmark between 1970 and 2009. We employed age-period-cohort models to model both the incidence and mortality rates of ALS over time for the first time. We found a significant rise in ALS incidence and mortality over several decades, and we observed evidence for a birth cohort component to the rise in ALS, which is consistent with an environmental cause of ALS. In Chapter II we investigate the role of physical trauma – both head and other – in the development of ALS. We employed the Danish registries and linked health data from the hospital system to prior diagnoses for physical trauma. We found a borderline significant association between physical trauma and ALS, which grew stronger upon restricting to physical traumas before the age of 55. Chapter III concerns the risk of ALS in those employed by the military in Denmark. We linked occupational records from the Danish Pension Fund to health records of the hospital system. We found a significantly elevated rate of ALS among those who had been previously employed by the military, with the highest rates in the decade immediately following cessation of employment. These analyses strengthen the knowledge base for the epidemiology of ALS, and suggest future avenues of research to further understand the etiology of the disease. |
