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The secrets of our ancestors might hold the key to why multiple sclerosis (MS) is more common among white, northern Europeans than among Europe’s more southern populations. While scientists have found hundreds of genes to date that are associated with MS, up to a fifth of northern Europeans have a genetic variant, called HLA-DRB1*15:01, that conveys a threefold higher risk of developing the autoimmune disease. Where this variant came from and why it persisted and spread is a mystery. An international team of researchers, led by William Barrie from the University of Cambridge, now thinks they are on to a new lead…..…Story continues…
By: Carly Cassella
Source: ScienceAlert
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Critics:
Multiple sclerosis (MS) is an autoimmune disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. Being a demyelinating disease, MS disrupts the ability of parts of the nervous system to transmit signals, resulting in a range of signs and symptoms, including physical, mental, and sometimes psychiatric problems.
Symptoms include double vision, vision loss, eye pain, muscle weakness, and loss of sensation or coordination. MS takes several forms, with new symptoms either occurring in isolated attacks (relapsing forms) or building up over time (progressive forms). In relapsing forms of MS, between attacks, symptoms may disappear completely, although some permanent neurological problems often remain, especially as the disease advances.
In progressive forms of MS, bodily function slowly deteriorates once symptoms manifest and will steadily worsen if left untreated. While its cause is unclear, the underlying mechanism is thought to be either destruction by the immune system or failure of the myelin-producing cells. Proposed causes for this include immune dysregulation, genetics, and environmental factors, such as viral infections. MS is usually diagnosed based on the presenting signs and symptoms and the results of supporting medical tests.
No cure for multiple sclerosis is known. Current treatments are aimed at mitigating inflammation and resulting symptoms from acute flares and prevention of further attacks with disease-modifying medications. Physical therapy and occupational therapy, along with patient-centered symptom management, can help with people’s ability to function.
The long-term outcome is difficult to predict; better outcomes are more often seen in women, those who develop the disease early in life, those with a relapsing course, and those who initially experienced few attacks. Multiple sclerosis is the most common immune-mediated disorder affecting the central nervous system. Nearly one million people in the United States had MS in 2022, and in 2020, about 2.8 million people were affected globally, with rates varying widely in different regions and among different populations.
The disease usually begins between the ages of 20 and 50 and is twice as common in women as in men. MS was first described in 1868 by French neurologist Jean-Martin Charcot. The name “multiple sclerosis” is short for multiple cerebro-spinal sclerosis, which refers to the numerous glial scars (or sclerae – essentially plaques or lesions) that develop on the white matter of the brain and spinal cord.
As multiple sclerosis (MS) lesions can affect any part of the central nervous system, a person with MS can have almost any neurological symptom or sign referable to the central nervous system. Fatigue is one of the most common symptoms of MS. Some 65% of people with MS experience fatigue symptomatology, and of these, some 15–40% report fatigue as their most disabling MS symptom. Autonomic, visual, motor, and sensory problems are also among the most common symptoms.
The specific symptoms are determined by the locations of the lesions within the nervous system, and may include focal loss of sensitivity or changes in sensation in the limbs, such as feeling tingling, pins and needles, or numbness; limb motor weakness/pain, blurred vision, pronounced reflexes, muscle spasms, difficulty with ambulation (walking), difficulties with coordination and balance (ataxia).
Problems with speech or swallowing, visual problems (optic neuritis manifesting as eye pain & vision loss, or nystagmus manifesting as double vision), fatigue, and bladder and bowel difficulties (such as urinary or fecal incontinence or retention), among others. When multiple sclerosis is more advanced, walking difficulties can occur and the risk of falling increases. Difficulties thinking and emotional problems such as depression or unstable mood are also common.
The primary deficit in cognitive function that people with MS experience is slowed information-processing speed, with memory also commonly affected, and executive function less commonly. Intelligence, language, and semantic memory are usually preserved, and the level of cognitive impairment varies considerably between people with MS.
Uhthoff’s phenomenon, a worsening of symptoms due to exposure to higher-than-usual temperatures, and Lhermitte’s sign, an electrical sensation that runs down the back when bending the neck, are particularly characteristic of MS, although may not always be present.
Another presenting manifestation that is rare but highly suggestive of a demyelinating process such as MS is bilateral internuclear ophthalmoplegia, where the patient experiences double vision when attempting to move their gaze to the right & left. Some 60% or more of MS patients find their symptoms, particularly including fatigue, are affected by changes in body temperature.
The main measure of disability and severity is the expanded disability status scale (EDSS), with other measures such as the multiple sclerosis functional composite being increasingly used in research. EDSS is also correlated with falls in people with MS. While it is a popular measure, EDSS has been criticized for some of its limitations, such as relying too much on walking.
The condition begins in 85% of cases as a clinically isolated syndrome (CIS) over a number of days with 45% having motor or sensory problems, 20% having optic neuritis, and 10% having symptoms related to brainstem dysfunction, while the remaining 25% have more than one of the previous difficulties.
Regarding optic neuritis as the most common presenting symptom, people with MS notice sub-acute loss of vision, often associated with pain worsening on eye movement, and reduced colour vision. Early diagnosis of MS-associated optic neuritis helps timely initiation of targeted treatments.
However, it is crucial to adhere to established diagnostic criteria when treating optic neuritis due to the broad range of alternative causes, such as neuromyelitis optica spectrum disorder (NMOSD), and other autoimmune or infectious conditions. The course of symptoms occurs in two main patterns initially:
Either as episodes of sudden worsening that last a few days to months (called relapses, exacerbations, bouts, attacks, or flare-ups) followed by improvement (85% of cases) or as a gradual worsening over time without periods of recovery (10–15% of cases).A combination of these two patterns may also occur or people may start in a relapsing and remitting course that then becomes progressive later on.
Relapses are usually unpredictable, occurring without warning. Exacerbations rarely occur more frequently than twice per year. Some relapses, however, are preceded by common triggers and they occur more frequently during spring and summer. Similarly, viral infections such as the common cold, influenza, or gastroenteritis increase their risk. Stress may also trigger an attack.
Many events have been found not to affect rates of relapse requiring hospitalization including vaccination, breast feeding, physical trauma, and Uhthoff’s phenomenon.
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