A treatment using particles from stem cells can slow and even reverse aspects of age-related memory decline, new research suggests.

The study found that tiny vesicles, small sacs released by bone marrow stem cells, helped maintain memory and improved communication between brain areas over two years in an experimental model.

Researchers at Boston University worked with middle-aged subjects.

Half received regular infusions of extracellular vesicles from young, healthy donor cells every two weeks for a year and a half, while the other half received a control without vesicles.

The vesicles contain molecules including proteins, lipids and RNAs that help reduce inflammation and support brain cells in responding to age-related stress.

Subjects completed memory and learning tests before and after treatment, and MRI scans assessed how efficiently different brain regions were connected.

At the end of the study, those who received the vesicles showed better working memory and signs of healthier brain connections.

“By applying secreted stem cells, specifically EVs, we found that the ageing brain retains a remarkable capacity for resilience,” said corresponding author Evan Mackie, a PhD student in the university’s department of anatomy and neurobiology.

“Our findings suggest that ageing is not set in stone; that brain health can be supported and maintained even in older age.”

The researchers describe this as the first study of its kind to show the treatment can protect the brain’s structure and function during normal ageing in a model closely related to humans.

Senior author Tara L Moore, professor of anatomy and neurobiology, added: “Because similar vulnerabilities in brain structure and function also occur in conditions such as Alzheimer’s disease, multiple sclerosis, stroke and brain injury, this approach may one day help protect the brain in both healthy ageing and disease.”

High-quality marriages may help protect against obesity by shaping communication between the brain and gut, new research suggests.

The study is described as the first to show how social bonds influence weight and eating behaviours through an integrated pathway involving brain activity, metabolism and oxytocin, sometimes called “the love hormone”.

The findings suggest relationship quality may matter as much to physical health as traditional risk factors such as exercise and diet.

“We’ve known for years that social relationships impact health, with supportive connections increasing survival rates by up to 50 per cent,” said lead author Dr Arpana Church, a neuroscientist at UCLA Health.

“The biological mechanisms explaining this connection have remained elusive. Our study reveals a novel pathway showing how marriage and emotional support literally get ‘under the skin’ to influence obesity risk.”

Researchers at UCLA Health studied nearly 100 participants from the Los Angeles area, collecting data on marital status, body mass index, diet and other factors.

They also carried out brain imaging while participants viewed food images, tested gut bacteria metabolites, measured blood oxytocin levels and assessed perceived emotional support.

Married people with higher emotional support had a lower body mass index and showed fewer food addiction behaviours than married peers with low support.

Brain scans showed greater activity in the dorsolateral prefrontal cortex, the region that helps control cravings and appetite, when they viewed food images.

Unmarried participants, whether highly supported or not, did not show the same brain patterns, possibly reflecting more varied and less consistent support networks.

Social support was also linked to shifts in gut metabolism. Those with stronger support showed beneficial changes in tryptophan metabolites, compounds made by gut bacteria that help regulate inflammation, immune function, energy balance and brain health.

Married participants with strong support had higher oxytocin levels than unmarried individuals.

The team suggests oxytocin may act as a messenger that strengthens brain regions involved in self-control while promoting healthier gut metabolic profiles.

“Think of oxytocin as a conductor orchestrating a symphony between the brain and gut,” said Church.

“It strengthens the brain’s ability to resist food cravings while promoting beneficial metabolic processes in the gut, both of which help maintain healthy weight.”

Church added: “Marriage may serve as a training ground for self-control. Maintaining a long-term partnership requires consistently overriding destructive impulses and aligning with long-term goals, which may strengthen the same brain circuits involved in managing eating behaviour.”

The authors noted limitations: the data were collected at one point in time, so causation cannot be confirmed; most participants were overweight or obese; and married participants tended to be older.

Fewer than one in 10 people who could benefit from GLP-1 drug treatment can access it, the WHO warns in its first guidance on obesity medicines.

With more than one billion people now obese and projections suggesting this could exceed two billion by 2030, the UN health agency is calling for wider and fairer access to GLP-1 medications.

High costs, limited production capacity and supply chain constraints are major barriers to access, the WHO said.

The medicines are already on the WHO essential medicines list for overweight patients with diabetes.

“Our new guidance recognises that obesity is a chronic disease that can be treated with comprehensive and lifelong care,” said WHO director-general Tedros Adhanom Ghebreyesus.

“While medication alone won’t solve this global health crisis, GLP-1 therapies can help millions overcome obesity and reduce its associated harms.

He added: “Our greatest concern is equitable access.”

GLP-1 drugs mimic a natural hormone to slow digestion, curb appetite and increase feelings of fullness, which helps people eat less.

People often start losing weight within weeks of weekly injections, though many regain weight within a year of stopping as appetite returns.

In the UK, these injections are prescription-only medicines. Some are available on the NHS, while more are sold privately.

The WHO warns against buying from unregulated sellers such as beauty salons or via social media.

Even in the best projected scenario, production could cover around 100 million people, under 10 per cent of those who need them, the WHO said.

The guidance urges countries and pharmaceutical companies to expand access through measures such as voluntary licensing, which lets other manufacturers produce affordable non-branded versions of patented drugs.

A patent on semaglutide, the core ingredient of Novo Nordisk’s Wegovy, is due to expire in several countries in 2026, allowing cheaper versions in markets including India, Canada, China, Brazil and Turkey.

Being overweight or obese raises the risk of diabetes, heart disease, stroke and some cancers. Obesity was associated with 3.7 million deaths worldwide in 2024, according to the WHO.