neurodegenerative diseases

A team from the University of Iowa (USA) has found a relationship between specific species of microbiota bacteria and the severity of multiple sclerosis. Specifically, a lower ratio between the quantities of Bifidobacterium and Akkermansia was related to the disease and to a worse course of the disease, both in mice and in two cohorts of patients and people without the disease. According to the authors, who publish the results in the journal PNAS, the finding could be used to improve the diagnosis and treatment of multiple sclerosis.

People with dementia who are prescribed a specific type of antidepressant experience a faster cognitive decline than people who do not use these drugs, according to a study published in BMC Medicine. In particular, prescriptions for higher doses of selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant, were associated with a higher risk of severe dementia, fractures and mortality. The analysis includes data from more than 18,000 patients from a Swedish database between 2007 and 2018.

A study by Italian researchers has tested a treatment administered as a nasal spray to slow down early-stage Alzheimer's disease. Administered in mice, the treatment inhibits an enzyme linked to the disease and to insulin resistance. According to the researchers, who publish the work in the journal PNAS, application of the spray to the animals “can counteract the accumulation of harmful proteins in neurons and delay the onset and progression of cognitive decline”. 

Less than four months after the European Medicines Agency recommended in July not to grant marketing authorisation for Leqembi™ (lecanemab) for the treatment of Alzheimer's disease, the EMA's Committee for Medicinal Products for Human Use (CHMP) has reassessed the available evidence to conclude that the benefits outweigh the risks.

Rituximab and ocrelizumab are two antibodies with a similar mechanism of action that are used in the treatment of multiple sclerosis. Although the former had not shown benefits in primary progressive multiple sclerosis — which affects between 10% and 15% of patients — the latter is approved for this form of the disease. Now, a study conducted in France with more than 1,000 patients has found no benefits with either treatment, as they did not slow the progression of disability in these individuals. The results are published in the journal Neurology.

Men and women could develop Alzheimer’s disease through different mechanisms. Understanding these differences is essential to design specific interventions and to treat the disease effectively. In an article published in Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association, a group of researchers, including myself, have highlighted the urgency of adding a sex and gender approach to the studies on this pathology.

Vision loss and having high cholesterol - the so-called ‘bad’ cholesterol - are risk factors for developing dementia, according to a meta-analysis published in The Lancet. Eliminating these risk factors could reduce dementia cases by 2% and 7% respectively, the study says. Both factors are in addition to 12 others previously mentioned in a 2020 report such as less education, physical inactivity, hearing loss, excessive alcohol consumption, obesity or poor social contact, among others. According to the research, almost half of all dementia cases could be prevented or delayed if these risk factors were controlled.

After the introduction of a shingles vaccine (Zostavax) in 2006, several studies suggested that the risk of dementia might be lower in people who had received the vaccine, although the results were inconclusive. In many countries Zostavax has been withdrawn and replaced by a much more effective vaccine (Shingrix). A study published today in Nature Medicine suggests that this new recombinant shingles vaccine, Shingrix, is associated with a greater reduction in the risk of dementia compared to Zostavax and vaccines against other types of infections.

In a new study in mice published in Science, researchers present CHARM, an epigenetic editor that can be used to silence prion protein throughout the brain. The tool offers a path to effective first-line treatment for patients with fatal prion diseases, as well as other neurodegenerative diseases caused by the toxic accumulation of unwanted proteins. 

A family of more than 1,000 members with origins in Colombia has a mutation called "paisa" that leads to the development of Alzheimer's disease. In 2019, an added mutation in the apoE gene called "Christchurch" was described as conferring strong protection to an individual carrying two copies of it. Now, a study has found that 27 family members carry a single copy and that it is also associated with some degree of protection. According to the authors, who publish their findings in the journal NEJM, the discovery could be used to develop new treatments for the disease.