A new study using MRI scans to detect brain lesions has revealed that instances of multiple sclerosis may be more active in spring and early summer months.

Researchers at the Brigham and Women's Hospital in Boston found that new lesions occurred two to three times more frequently in spring and summer compared to the colder climates of the year.

It is estimated that more than 400,000 people in the United States suffer from MS as per data released by the National Multiple Sclerosis Society while the figure worldwide could be more than two million.

The exact causes of MS is unknown and scientists believe that it is an autoimmune disease under which the body's immune system mistakenly turns on itself and damages or destroys healthy cells instead of diseased ones. "We've found increased levels of this disease activity during spring and summer, say the authors in a report published in the latest issue of Neurology.

Both genetic and environmental factors are spoken of as causing the disease with doctors also suggesting that environmental factors including geography and deficiency of vitamin D as other reasons for its manifestation.

The study involved 939 brain scans across a sample size of 44 people diagnosed with MS around the Boston area. During the course of the study between 1991 and 1993, the patients were not receiving any treatment and each person underwent a scan on 22 occasions on an average.

Thereafter, the study group collected the data related to daily temperature, solar radiation and precipitation in the area and found that in a span of one year, 310 new brain lesions were formed in 31 people while the remaining 13 did not show any signs of new lesions being formed.

They also found that between March and August, the occurrence of ne lesions were two to three times higher compared to the fall and winter months which also seemed to indicate that warmer temperatures and solar radiation were associated with heightened activity of the disease.