New study shines light on causes of dementia

A new study led by the University of Portsmouth in England has identified a significant feature in the deterioration of the 'insulation' of the wiring of the human brain, which could play a major role in the prevalence of neurodegenerative conditions such as Multiple Sclerosis (MS) and Alzheimer's, which is a major medical challenge facing the ageing society of China and other countries.

The substance in question is called myelin and acts as a protective casing for neurological electrical connections called axions, enabling the high-speed sending of messages between nerve cells.

The research team, led at Portsmouth by Arthur Butt, and working in conjunction with colleagues at the University of Dusseldorf in Germany, and Italian research groups in Milan and Padua, have published a study in the medical journal, Ageing Cell.

This highlights how the cells that help repair myelin become less reliable as people get older, and they have identified the gene that is most affected by the ageing process, reducing the ability to repair lost myelin.

Dementia and associated medical conditions, particularly Alzheimer's, are a major global medical concern, especially in China, whose ageing population presents significant challenges in the years ahead.

In December 2020, Civil Affairs Minister Li Jiheng was quoted by the South China Morning Post as saying the country's number of senior citizens, aged 60 and older, will have risen to 300 million in the next five years.

That figure is expected to hit 400 million by 2033 and peak at 487 million by 2053, meaning that by the middle of this century, one in every three or four Chinese people is likely to be a senior citizen, facing the medical challenges that come with ageing.

In April 2020, Xinhua reported that the World Health Organization had estimated at least 50 million people worldwide had dementia, with Alzheimer's being the root cause of between 60 and 70 percent of cases.

A study by Scottish-based organization Care Visions published on the website BMJ Case Reports in March 2020 said that China has the world's largest population of people over the age of 80, and around one-fifth of all Alzheimer's patients worldwide, which is projected to rise from 14.1 million in 2020 to 23.3 million people by the year 2030.

Multiple sclerosis, an incurable disease caused by the immune system attacking the central nervous system, leading to difficulty with movement and impaired memory, is less prevalent in China. Figures quoted by Reuters in May 2020 estimated the country had around 30,000 sufferers, out of more than 2.5 million people affected worldwide.

"Everyone is familiar with the brain's gray matter, but very few know about the white matter, which comprises of the insulated electrical wires that connect all the different parts of our brains," said Butt, the research team leader.

"A key feature of the ageing brain is the progressive loss of white matter and myelin, but the reasons behind these processes are largely unknown. The brain cells that produce myelin — called oligodendrocytes — need to be replaced throughout life by stem cells called oligodendrocyte precursors. If this fails, then there is a loss of myelin and white matter, resulting in devastating effects on brain function and cognitive decline. An exciting new finding of our study is that we have uncovered one of the reasons that this process is slowed down in the ageing brain."

The vital gene that has been identified is called GPR17. Its loss is linked to an impaired ability to replace lost myelin. Research team member Kasum Azim, from the University of Dusseldorf, called this breakthrough "promising" in helping understand the process that led a number of common degenerative conditions, with more discoveries yet to come.

"We have only touched the tip of the iceberg and future investigation from our research groups aim to bring our findings into human translational settings," he added.

Emma Gray, Assistant Director of Research at the MS Society in the United Kingdom, called the condition "relentless and painful" but said the research, which the society had helped fund, did offer hope.

"This research sheds light on why cells that drive myelin repair become less efficient as we age, and we're really proud to have helped fund it," she said.

"By improving our understanding of ageing brain stem cells, it gives us a new target to help slow the progression of MS, and could have important implications for future treatment."