Co-morbidities in MS

In principle, MS does not directly predispose to other diseases. As genetic susceptibility factors are common to other autoimmune diseases such as rheumatoid arthritis, lupus erythematosus, psoriasis, juvenile diabetes, and Crohn's disease, some patients suffer from both MS and one or other of these diseases. This is not a coincidental association. Similarly, the incidence of autoimmune thyroiditis is higher in patients with MS. Uveitis, i.e. inflammatory eye disease, is 10 times more common in people with MS than in the general population. In these cases, the associated autoimmune disease develops independently of MS, with its own relapses and remissions, and must therefore be treated specifically and independently thereof. These autoimmune diseases are also found more frequently in the families of people with MS.

In addition, loss of mobility and lack of physical exercise can lead to excess weight gain and metabolic disorders with disturbed blood lipids, diabetes, atherosclerosis, and cardiovascular disease. These can alter cerebral blood circulation, both in the large arteries and in the small vessels, causing cerebral thrombosis and accentuating cerebral atrophy. The patient must be helped to combat an excessively sedentary lifestyle, which leads to muscular atrophy as a result of under-use (known as sarcopenia). Physical exercise and targeted physiotherapy are an integral part of the treatment of progressive MS.

Infections are not more common in people with MS, and in fact the opposite is often observed. There are fewer viral infections of the upper respiratory tract, for example. Infections can be secondary to urinary problems such as cystitis and pyelonephritis, swallowing problems such as inhalation pneumonia, or infected bedsores. They can also be caused by certain medications used in MS.

No increase in cancers was observed in MS patients.

On the other hand, psychological and sometimes psychiatric disorders are more frequently encountered in MS patients than in the general population.

The World Health Organisation (WHO) defines health as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity". According to the WHO, "mental health is a state of well-being that enables people to achieve their potential, cope with the normal difficulties of life, work successfully and productively, and be able to make a contribution to the community". Given the difficulty of finding objective criteria for mental health, the American Psychiatric Society has identified around 400 different types of mental disorder... We therefore need to define those most frequently encountered in MS.

Reactional psychological distress may be in response to bereavement, failure at school or at work or in relationships, or the realisation of a loss of physical health. This is a normal adaptive reaction. It can, of course, accompany the announcement of the diagnosis of MS. It does not necessarily have to be treated specifically. The person himself or herself can overcome the grief caused by the announcement of a chronic illness, thanks to his or her own psychological resistance, the people around him or her and the explanations given about the illness, in the knowledge that he or she will not be fighting it alone.

Reactive psychological distress can lead to chronic depression. In all the publications on the subject, depression is the leading cause of impaired mental health in people with MS. It was reported in 46% of patients in a 2009 study, in around 50% of patients in a 2011 study, and in 24% in a 2015 study. The symptoms are not specific to MS. These include low morale, an inability to enjoy life as it used to be, fatigue, insomnia and an altered appetite. The vital impetus is broken, there is a tendency to put off necessary activities until tomorrow or later (procrastination), dark thoughts, urges to cry, tears. Symptoms are always more marked in the morning, when you're faced with a blank page for the day, than at the end of the day.

This percentage of depressive symptoms is around 3 times higher than in the general population. The rate of "successful" suicide is also approximately 2 times higher and is mainly committed by young male patients during the first 5 years of diagnosis, regardless of physical disability.

 Depression can be treated in a number of ways: by medication using selective serotonin reuptake inhibitors, by talking (psychotherapy) with a psychiatrist or clinical psychologist, or by mindfulness techniques, although these therapeutic methods are not mutually exclusive. It was also reported in 2021 that there was an improvement in depressive symptoms when stopping cannabis use.

Excessive or pathological anxiety is the 2^nd major symptom of impaired mental health in MS studies, up to 16.5% of people in a 2009 study, 22% in a 2015 study. Of course, there is such a thing as 'normal' anxiety, i.e. the anxiety of every young mother for her child, for example, and the more recent phenomenon of eco-anxiety, which should be interpreted as a positive feeling because it bears witness to a love of the world and implies a detachment from oneself: people suffer for others, for the world (Corinne Pelluchon, philosopher). In practice, anxiety is mainly linked to the fear of having another attack that will leave after-effects and that will occur unpredictably but always at the worst possible time... Another common anxiety is that of losing the ability to walk independently and being confined to a wheelchair. This is understandable anxiety, but it should not condemn us to inactivity and passivity. It should be remembered that our most effective medications today reduce the frequency of relapses to one every 10 years on average, and that the proportion of people with MS requiring walking aids at the age of 50 or over has fallen from 27% when the disease was diagnosed before 2000 to 15% when it was diagnosed after 2000. We can be sure that this percentage will be even lower for people diagnosed after 2010.

Obviously, everyone who is diagnosed with MS has his or her own past, his or her own childhood and adolescence, fears and pre-existing anxieties: no one is a 'virgin' when it comes to psychological weakness. The announcement of the diagnosis can then exacerbate hypochondriac tendencies, provoke a multifaceted "boo-boo care", and sometimes encourage the somatisation of emotional or sentimental problems in the aftermath of a previous attack. These sequelae may suddenly worsen even though there is no real underlying attack. The aim is to explain, deconstruct imaginary films and open up ways out, while respecting each patient's psychological defence mechanisms.

Bipolar disorder (formerly known as manic-depressive psychosis) is on average 2 times more common in people with MS than in the general population. In MS patients, the frequency was estimated at 2.4% in a 2009 study, 5.8% in a 2015 study and 6.5% in a 2017 study, which compares this percentage with 3.4% in the general population. Bipolar disorder may be present before the diagnosis of MS. There is currently no explanation for this relative association between MS and bipolar disorder. In both cases, there are familial forms with susceptibility genes, but these are not the same in the two diseases. When bipolar disorder pre-exists MS, the diagnosis of the latter is more difficult and is therefore delayed, with the result that treatment is also delayed. In the most severe forms with extreme agitation, there may be paranoid delusions, such as claims of being robbed, cheated, locked up, poisoned, etc. These manic episodes require specific treatment by a psychiatrist. Treatment should be chronic, to avoid alternating between manic agitation and melancholic depression.

It should also be added that, rarely, high-dose cortisone treatment for severe flare-ups can induce a manic state with hyperagitation, in which case cortisone is not only an anti-inflammatory but also an artificial psychic doping agent.

Mental state disturbances such as those described above unfortunately interfere with regularity and adherence to MS treatment. They must be treated without delay in the same way as any other co-morbidity.

Life expectancy was analysed in a Norwegian study of a population followed for 60 years. The median life expectancy (i.e. 50% above and 50% below the retained figure) was 74.7 years for people with MS and 81.8 years in the general population, a difference of 7 years. It is lower in people with primary-progressive MS (71.4 years) than in those with initial relapses (77.8 years). The main causes of death linked to MS are pneumonia due to false swallowing and urinary tract infections with kidney damage and septicaemia.