Risk factors in the early diagnosis of ALS: North American epidemiologicalstudies

Patient-specific (endogenous) and population-specific (exogenous) risk fact or analysis is identifying novel physical and chemical exposures which migh t be time-linked to the development of amyotrophic lateral sclerosis (ALS) and other motor neuron diseases. Electric injury in a number of case-contro l studies as well as prolonged exposure at work and home to agricultural ch emicals in pesticides and herbicides have been identified as significant ri sk factors. Heavy exercise, trauma with or without bone fractures and heavy metal exposure at work have not been confirmed as risk factors. Surprising ly, occupation as a pilot or navigator has recently been identified as a po tential risk factor, which will need to be confirmed. The introduction of i nternational patient registries in North America (ALS CARE) and in Europe ( ALS HPS) will facilitate future studies on the prognosis of ALS, adherence to standards of practice, quality of life and patient outcome studies. An i nitial survey of the ALS Patient Care Database in January 1999, when nearly 1800 patients had been entered across North America, indicated the median time from ALS onset to diagnosis is 14 months when no second opinion is req uested, 13. months if the patient requests a second opinion and 10 months w hen the neurologist requests an additional opinion. No significant differen ce was found in the median time to diagnose sporadic ALS patients compared with familial ALS patients.