"Our study suggests that doctors who treat people with chronic diseases should not attribute new neurological symptoms such as numbness and tingling to existing conditions without careful consideration," said study author Ruth Ann Marrie, MD, PhD, of the University of Manitoba in Winnipeg, Canada, and member of the American Academy of Neurology.
For the study, researchers examined the records of 8,983 people who had been diagnosed with MS. Of those, 2,375 were further classified as having mild, moderate or severe disability within two years of diagnosis. This well-characterized group was asked about pre-existing health conditions, their smoking status and weight history.
The study found that it took one to 10 years longer for people who were obese, smoked, or had physical or mental health conditions to be diagnosed with MS compared to people without such conditions. The study also found that the more medical problems a person with MS had, the more severe the disease had become by the time they were diagnosed.
"People with vascular problems or who were obese were about one-and-a-half times more likely to be moderately disabled at the time of diagnosis compared with those who had MS but did not have any heart or weight problems," said Marrie. "We also found people who had a mental disorder or any muscle or joint problem along with MS were nearly two times more likely to be severely disabled at the time of diagnosis."
Marrie says pre-existing conditions are common in the United States and can mask symptoms of a new disease or affect access to patient care. "People with multiple medical problems on top of MS may need more healthcare resources or might respond differently to medication," Marrie said. "This needs more study."