A long-awaited study shows no evidence of geographic clusters or unusually high numbers of cases of multiple sclerosis and amyotrophic lateral sclerosis in Southeastern Massachusetts, officials from the state Department of Public Health said. The study focused on communities surrounding the former South Weymouth Naval Air Station — Abington, Rockland, and Weymouth — and the town of Middleborough, which is home to several hazardous waste sites. The study, presented to the public at a meeting at Town Hall Thursday, tracked people who were diagnosed with MS and ALS in those areas between 1998 and 2003. Researchers found a higher prevalence of MS in the towns around the former air base, but the people with the disease tended not to live close to the base.Emily Sweeney can be reached at firstname.lastname@example.org. Follow her on Twitter @emilysweeney.