Approximately 2.5 million people worldwide are living with multiple sclerosis and 200 people are diagnosed with the disease every day. Now, two new studies suggest that the “obesity hormone” leptin and hormones used in birth control pills may increase the risk of multiple sclerosis.

The findings will be presented at the American Academy of Neurology’s 66th Annual Meeting in Philadelphia, PA, in April.

Multiple sclerosis (MS) is a disease of the central nervous system. Onset of the condition is most common between the ages of 20 and 40.

The majority of MS patients experience muscle weakness and have difficulty with coordination and balance. In severe cases, the condition can cause partial or complete paralysis.

As yet, it is unknown as to exactly what causes MS. However, some researchers hypothesize that the immune system in the body acts abnormally and attacks the central nervous system. Environmental and genetic factors are also thought to be a cause of MS.

Now, two new studies suggest other factors that may contribute to increased risk of the disease.

For the first study, Dr. Jorge Correale, of the Raúl Carrera Institute for Neurological Research in Buenos Aires, Argentina, and colleagues analyzed the body mass index (BMI) of 420 individuals aged 15 or 20 years.

Of these participants, 210 had MS while the other 210 were free of the disease at the baseline of the study.

The investigators found that participants who were obese at the age of 20 were twice as likely to develop MS later in life, compared with individuals of the same age who were not obese.

Furthermore, the results of the study revealed that participants who had a high BMI also had high levels of leptin in their blood – a protein produced by fatty tissue that regulates the storage of fat in the body, as well as appetite and immune response.

Dr. Correale says that because leptin promotes inflammatory responses in the body, this could explain the association between obesity and MS.

For the second study, researchers from Kaiser Permanente Southern California analyzed 305 women who had been diagnosed with MS or clinically isolated syndrome – a precursor to the disease.

All women were members of Kaiser Permanente Southern California 3 years prior to the development of MS symptoms.

The women were assessed for their use of birth control pills and were compared with 3,050 women who were free of MS.

In the 3 years before MS symptoms began, 29% of women with MS had used hormonal contraceptives for at least 3 months, while 24% of women without MS had used birth control pills. Most of the women took pills that were a combination of estrogen and progestin.

The results of the study revealed that women who used birth control pills were 35% more likely to develop MS, compared with women who did not use them. Women who had stopped using hormonal contraceptives 1 month before MS symptoms began were 50% more likely to develop the disease.

Commenting on the research, lead study author Dr. Kirstin Hellwig says:

These findings suggest that using hormonal contraceptives may be contributing at least in part to the rise in the rate of MS among women.”

Medical News Today recently reported on a study suggesting that it could be possible to detect MS years before the onset of symptoms using antibodies as a biomarker for the condition.