While studying birth cohort issues, the authors focused also on the seasons of birth in amyotrophic lateral sclerosis (ALS). The analyses were based on computerized death records of Swiss mortality statistics 1969-1993. The results confirm an excess of births in spring months. They suggest that risk factors in ALS can be acquired very early in life, thus introducing a long latency period.
PIP: Swiss mortality statistics for the period 1969-93 were used to examine season of birth patterns of amyotrophic lateral sclerosis (ALS) and other neurologic diseases. Of the 1,476,002 deaths recorded during this period, 2178 ALS entries were found. Both the Edwards' test and Wallenstein's rachet scan statistics confirmed an excess of births among ALS patients in the spring months (March-May). Given the narrow peak in season of birth, it is likely that infectious diseases are the risk factor. It has been argued that ALS develops after a long latency period introduced by infectious diseases occurring in childhood or youth.