Toronto, Sep 26 : People are nearly twice as likely to experience mental illness in the years leading up to the onset of multiple sclerosis (MS), new research has shown. MS is an autoimmune disorder in which the immune system attacks the protective sheath (myelin) that covers nerve fibres, disrupting communications to and from the brain. Recognising MS is often challenging for medical professionals because its symptoms are varied and easily mistaken for other conditions. The study, published in the journal Neurology, suggests that psychiatric conditions like anxiety and depression may be part of a prodromal phase of MS -- a set of preliminary symptoms and clues that arise before classic MS symptoms. 'For a long time, it was thought that MS only really began clinically when a person experienced their first demyelinating event, such as in the form of vision problems,' said Helen Tremlett, Professor of neurology at University of British Columbia (UBC). 'But we've come to understand there is a whole period preceding those events where the disease presents itself in more indirect ways,' she added. For the study, the researchers examined health records for 6,863 MS patients. They looked at the prevalence of mental health conditions, including depression, anxiety, bipolar disorder and schizophrenia, in the five years before patients developed classical, medically recognised signs of MS. These MS patients were compared to 31,865 patients without MS. The findings revealed that MS patients were experiencing mental illness at nearly twice the rate of the general population, at 28.0 per cent and 14.9 per cent respectively. Healthcare usage for psychiatric symptoms -- including physician and psychiatrist visits, prescriptions, and hospitalisations -- was also consistently higher among MS patients. Notably, the gap widened in each of the five years leading up to disease onset. ' We see higher and higher rates of psychiatric conditions that peak in the final year before MS onset,' said first author Anibal Chertcoff, Assistant Professor at the University of Manitoba. 'While we're not suggesting that these conditions alone can be a predictor of MS, they may be one piece of the MS prodrome puzzle and a potential signal when combined with other factors.' /IANS