RAVAGED nerve cells in the brain and spinal cord of deceased multiple sclerosis patients have thrown up clues that may eventually lead to a drug treatment which can halt the downward spiral of symptoms.

Scientists in Edinburgh compared tissue samples donated for medical research from people with both the progressive and relapsing forms of MS as well as people without the disease. They found the the nerve cells in progressive MS patients are no longer able to generate mitochondria - the cell's "power packs" which covert oxygen and nutrients into a power generators of the cell, converting oxygen and nutrients into molecules which fuel the body's metabolic activities.

This is particularly important for MS patients as the body's demand for energy increases as myelin, the fatty coating which insulates nerve cells, is destroyed - one of the consequences of MS.

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Dr Don Mahad, a consultant neurologist and research based at Edinburgh University's Centre for Clinical Brain Sciences, said: "You have a situation where the energy demand goes up because myelin gets damaged but the ability to supply energy goes down because mitochondria in the cell body become damaged. It's a combination of increase demand and reduced supply which critically compromises the nerve cell in progressive MS.

"Our work from the postmortem tissue, really looking inside the nerve cell, tells us that there are changes and that the nerve cells in progressive MS are not normal. Really when it comes to designing new therapies in the future this is clearly a piece that we have to consider."

Unlike relapsing-remitting MS, which is more common, patients with progressive MS currently have no drugs and face a steady deterioration in symptoms with no periods of relief.

One worldwide clinical trial, which is set to launch its Scottish arm next month, will test whether giving progressive MS patients high doses of the vitamin biotin can "recharge" mitochondria and alleviate symptoms. Meanwhile, authorities in the US have recently licensed the world's first ever treatment for progressive MS - a drug called ocrelizumab. It will be up to the European Medicines Agency to approve it for use here, with a decision expected in autumn, before the Scottish Medicines Agency can consider whether to prescribe it on the NHS. However, ocrelizumab - which can also be given to patients with relapsing MS - specifically targets inflammation, rather than restoring myelin or rebooting mitochondria.

Dr Mahad, who specialises in MS research, said a truly effective therapy for progressive MS patients "would have to tackle all three pieces". He added that the current lack of therapies was also slowing diagnoses.

He said: "Before the 1990s, neurologists often didn't give a diagnosis of MS to patients until they were pretty badly affected, because we didn't have any drugs. But once we got drugs for relapsing MS that really transformed the way we diagnose it because we want to pick it up really early.

"Now the same is really true for progressive MS - because we don't have any treatment for progressive MS we've been delaying the diagnosis of PMS because there's no incentive. You're telling people they've got a bad condition that's untreatable."

Dr Mahad is currently leading research into performance fatigue in mice and in progressive MS patients which he hopes could lead both to potential drug therapies as well as early detection of progressive MS, before walking is impaired.

Morna Simpkins, director of MS Society Scotland, said: “Around 15 per cent of people are diagnosed with primary progressive MS - this means that they don’t experience periods of recovery. At the moment, there are no licensed treatments licensed in the UK for this type of MS which could slow down disability progression – but there is now some hope.

“Earlier this year a drug called ocrelizumab was approved for use for people with primary progressive MS in the US – and it’s now being reviewed by the European Medicines Agency. If this does become licensed we’ll be working with the SMC and NHS to make this treatment available for people with MS who are eligible, regardless of where they live in Scotland.

“And at the MS Society, we’re really focused on funding research to find more effective treatments for people with progressive forms of the condition.”