What’s impact of rising temperatures on people with MS? It may worsen symptoms, send more to hospital: Study
Heat sensitivity is common in multiple sclerosis (MS) and climate scientists expect that periods of anomalously warm weather will become more frequent with climate change. As average temperatures climb around the world, a research team has found that people with multiple sclerosis may expect worsening symptoms, enough to send them to the hospital more often.
“Our study suggests that warming trends could have serious health implications over the long term for people living with MS,” warns Dr Holly Elser from the Stanford University School of Medicine in Stanford, California, and a member of the American Academy of Neurology. The preliminary findings are being presented at the American Academy of Neurology’s 73rd annual meeting.
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What is MS?
Multiple sclerosis is a potentially disabling disease of the brain and spinal cord (central nervous system). According to the National Multiple Sclerosis Society, over 2.3 million people globally have a diagnosis of MS. It estimates that nearly 1 million people in the US over the age of 18 live with a diagnosis of MS.
“An unpredictable disease of the central nervous system, multiple sclerosis can range from relatively benign to somewhat disabling to devastating, as communication between the brain and other parts of the body is disrupted. Many investigators believe MS to be an autoimmune disease, one in which the body, through its immune system, launches a defensive attack against its own tissues. In the case of MS, it is the nerve-insulating myelin that comes under assault. Such assaults may be linked to an unknown environmental trigger, perhaps a virus,” explains the National Institute of Neurological Disorders and Stroke (NINDS), which is a part of the US National Institutes of Health.
MS can cause a wide range of symptoms and each person with the condition is affected differently. Some of the symptoms include fatigue; numbness and tingling; vision problems; muscle spasms; stiffness and weakness; pain; mobility problems; problems with thinking, learning and planning; depression and anxiety; and speech and swallowing difficulties, among others. “Most people experience their first symptoms of MS between the ages of 20 and 40; the initial symptom of MS is often blurred or double vision, red-green color distortion, or even blindness in one eye. Most MS patients experience muscle weakness in their extremities and difficulty with coordination and balance. These symptoms may be severe enough to impair walking or even standing. In the worst cases, MS can produce partial or complete paralysis,” state experts.
There is currently no cure for MS. However, treatments can help speed recovery from attacks, and manage symptoms. “Many individuals do well with no therapy at all, especially since many medications have serious side effects and some carry significant risks. Steroid drugs may be prescribed to treat acute symptoms of an attack, such as inflammation; they do not affect the course of the disease over time. Several drugs have been approved by the US Food and Drug Administration (FDA) to treat one or more forms of multiple sclerosis, either by decreasing attack frequency and severity, treating relapses, or delaying disease progression,” says the NINDS.
What did the researchers find?
The team wanted to determine if rising temperatures send more people with MS to the hospital. They looked at insurance claims for 106,225 people with MS living across the US. The investigators calculated the estimated effect of anomalously warm weather on MS-related emergency department, inpatient, and outpatient visits. They then compared the number of medical visits for each person during periods of anomalously warm weather to periods of normal weather.
Anomalously warm weather was defined as any month in which local average temperatures were higher than the long-term average temperature for that month by at least 1.5 degrees Celsius, or almost 2 degrees Fahrenheit.
The analysis reveals that during periods of anomalously warm weather, participants had a 4% increased chance of having an emergency department visit compared to periods of normal weather. Participants had a 3% increased chance of having an inpatient visit and a 1% increased chance of having an outpatient visit during anomalously warm periods compared to periods of normal weather.
The authors estimate that throughout follow-up, periods of anomalously warm weather were associated with an estimated excess of at least 592 emergency department visits, 1,260 inpatient visits, and 1,960 outpatient visits related to MS. “While the relative increase in the risk of visits is small, the associated absolute effect on people with MS and the healthcare system is meaningful,” emphasizes Elser.