Alzheimer's

A team from the United States analyzed blood levels of three biomarkers associated with Alzheimer’s disease in 1,350 people without dementia, with an average age of 61. Higher levels were associated with poorer cognitive performance five years later, leading the authors to state that the findings “demonstrate the potential for early detection of Alzheimer’s disease in middle-aged adults through blood tests.” In a related commentary, two experts who did not participate in the study state that, in young populations without cognitive impairment, these tests “may generate a higher rate of false positives” and caution that “they are not suitable for mass, non-selective screening for Alzheimer’s disease pathology in cognitively healthy populations or in the general community.” The study is published in The Lancet.

A review of studies conducted by the Cochrane Collaboration analyzed data from 17 clinical trials involving more than 20,000 participants who had been treated with amyloid-targeting drugs—such as lecanemab or donanemab—at a relatively early stage of Alzheimer’s disease. Results at 18 months of treatment show that “the absolute effects on cognitive decline and the severity of dementia were nonexistent or negligible, falling well below the thresholds established for a clinically meaningful difference,” according to a press release. Furthermore, the review concludes that these drugs likely cause more brain inflammation and microbleeds than the placebo.

Oral semaglutide is not effective in slowing the progression of the disease in patients with mild Alzheimer’s disease, according to the findings of the first large-scale, randomised phase 3 clinical trials published in The Lancet. In these trials, around 3,800 patients aged between 55 and 85 with a confirmed diagnosis and mild symptoms received up to 14 mg daily of oral semaglutide or a placebo. After two years, no significant difference in disease progression was observed. 

CAR-T cells, T lymphocytes modified in the laboratory to attack tumor cells, have shown promise against certain types of cancer. Now, a US team has followed the same concept and introduced artificial receptors into astrocytes, a type of nerve cell, with the aim of reducing the amyloid plaques characteristic of Alzheimer's disease. The experiments, conducted in mice, showed a significant reduction in amyloid, although no changes in the animals' behavior were observed. The results are published in Science. 

Physical inactivity is a risk factor for the onset of Alzheimer's disease. An international team has studied nearly 300 people with preclinical Alzheimer's—without symptoms but with an accumulation of tau and beta-amyloid proteins in the brain—for 14 years to find out whether physical exercise can also influence its progression. The results indicate that even very moderate activity—walking between 3,000 and 5,000 steps per day—was associated with slower deterioration, while the benefits—which appear to be related to lower tau protein deposits—were greater and tended to stabilise with activity involving between 5,000 and 7,500 steps. The results are published in the journal Nature Medicine.

An international team with Spanish participation has analyzed data from more than 500,000 people and found a link between digestive disorders such as colitis, gastritis, esophagitis, or functional bowel disorders and an increased risk of developing Alzheimer's and Parkinson's diseases. According to the researchers, who published their findings in the journal Science Advances, “this effort sheds light on the interaction between factors involved in the gut-brain axis and opens avenues for targeted treatment and early diagnosis.”

Researchers at Harvard Medical School have published new findings in Nature on the role of reduced lithium levels in Alzheimer's disease, based on experiments with mice and analysis of brain tissue and blood samples from humans. The team claims to have achieved improvements in memory in mouse models with lithium orotate. They caution that they have not proven that lithium is safe or effective in protecting against neurodegeneration in patients, and that their findings must be confirmed in humans through clinical trials.

Alzheimer's disease, the most common form of dementia, is linked to the presence of tau protein deposits and amyloid plaques in the brain. Now, a team at Johns Hopkins University (USA) has identified more than 200 misfolded proteins in rat brains that are associated with age-related cognitive decline. Although the study does not allow us to know whether they play a causal role, the authors claim that amyloid plaques ‘are just the tip of the iceberg.’ The results are published in the journal Science Advances.

A US team has analysed the presence of beta-amyloid deposits – which are linked to Alzheimer's disease – in the post-mortem retinas of four people with covid-19 and found that they were larger than in four people without covid. In complementary experiments, the SARS-CoV-2 spike protein in retinal organoids produced an increase in deposits, while the use of a drug that blocks the virus from binding to neurons reduced their accumulation. The results are published in the journal Science Advances.

A US study analysing data from nearly 700,000 people concluded that those with a history of herpes simplex virus (HSV-1) infections were at greater risk of developing Alzheimer's disease. The study, published in BMJ Open, also showed that patients with this virus who used anti-herpes treatments were less likely to develop the disease.