A man who became paralysed after a diving accident six years ago regained the ability to move and feel pressure in his hands thanks to brain stimulation. Now, researchers have revealed he maintained this ability for months after the stimulation was turned off. This suggests the intervention has caused a rerouting of his neuronal connections through neuroplasticity.

ā€œWe turned everything off completely, for many months, and yet heā€™s maintained these gains,ā€ says at the Feinstein Institutes for Medical Research in New York. ā€œThatā€™s unheard of.ā€

Keith Thomas, 48, was paralysed from the chest down in July 2020. He had no sensation or control over his limbs and had significant muscle wasting, says Bouton.

In 2023, Bouton and his colleagues performed a double neural bypass surgery on Thomas, placing five electrodes into his brain in regions associated with arm movements and feeling. They then connected computer cables to these electrodes, so artificial intelligence could interpret his movement intentions. That information was then wired into electronic splints that stimulated his arms, hands and fingers to carry out his intended movements, enabling him to pick up coffee cups and scratch his face.

To recreate the sense of feeling, the team embedded force sensors into 3D-printed wearable devices for Thomasā€™s hands and fingers, which sent feedback via electrical stimulation into the brainā€™s sensory areas.

After conducting a series of experiments ā€“ which even involved Thomas feeling objects through another personā€™s hand ā€“ Bouton says the team planned to stop the stimulation for about a month, to test for any lingering effects. ā€œThen we had a fire in the building, and it actually forced us to stop stimulation for even longer than weā€™d planned, for about three months.ā€

The unexpected interruption led to surprising findings: Thomas continued to maintain strength, feeling and function in his hands. ā€œHeā€™s now also controlling individual fingers with even more accuracy, so thatā€™s big,ā€ says Bouton.

In a video interview with New Scientist, Thomas raised his elbows nearly to shoulder level and described feeling ā€œtinglingā€ in his wrist in response to pressure, even when heā€™s ā€œunplugged from the computerā€. ā€œWhen I first felt it, it was amazing,ā€ he says. ā€œIā€™m used to it now.ā€

Ā at the University of California, Davis, says the work suggests that this approach promotes lasting recovery of the nervous system. ā€œThe goal is to help the nervous system partially heal so the person can move their own body better,ā€ he says.

Free newsletter

Sign up to ĪēŅ¹ø£Ąū1000¼ÆŗĻ Check

Sign up to newsletter

ā€œIf these improvements persist even when the system is turned off, then the device is doing more than temporarily restoring function,ā€ says at the University of California, Los Angeles. ā€œIt may be helping the nervous system reorganise itself through neuroplasticity.ā€

This describes the brainā€™s ability to rewire itself by forming new neural connections, such as or even . ā€œAfter an injury such as spinal cord injury, those same mechanisms may help restore function by strengthening spared pathways or recruiting alternative circuits, allowing neural signals to travel through networks that were previously too weak to support meaningful movement,ā€ says Lu.

The researchers have observed stronger neural responses in Thomasā€™s sensory cortex since the intervention.

But this is just a single case report, so itā€™s unclear how well this approach would work on other people with paralysis from different types of injuries. at the University of Chicago says he has spent years working on stimulation and continues to find that some respond better than others, and some not at all. ā€œAnd we have no idea why,ā€ he says. ā€œSo, the question is: can you replicate it? This is a really ambitious study, but we need to see them replicating their results in more participants before we believe the hype.ā€

As to Thomasā€™s future, ā€œat this point now we know nothingā€™s impossible, or anythingā€™s possibleā€, says Boulton. ā€œI think itā€™s possible he will continue to to improve,ā€ he adds.

A cognitive ā€œspeed trainingā€ game that cuts dementia risk by 25 per cent alters levels of beta-amyloid, a protein that clogs up the brain in Alzheimerā€™s disease, in men, but not in women.

It is the first time brain training has been shown to influence the levels of a neurodegenerative marker, strengthening the evidence suggesting that mental exercises can boost brain health.

ā€œOne of the main markers thatā€™s indicative of future dementia risk got better for men who completed cognitive speed training,ā€ saysĀ Ā at Clemson University in South Carolina, who presented the research at the Alzheimerā€™s Association International Conference in London on 12 July.

The computer-based speed training involves recalling where objects have flashed up, with the task becoming harder as performance improves. A prior 20-year study by some of Chaiā€™s colleagues showed that people aged 65 and older, who did the training wereĀ 25 per cent less likely to be diagnosed with Alzheimerā€™s diseaseĀ or a related form of dementia compared with a control group.

In the latest study, Chai and her team recruited a separate group of 53 people from the US aged 65 and older, 13 of whom were male. About a third of the participants were asked to complete between 2 and 4 hours of speed training each week for 4.5 months.

Free newsletter

Sign up to ĪēŅ¹ø£Ąū1000¼ÆŗĻ Check

Sign up to newsletter

The remaining participants were either told to spend the same amount of time playing games such as Solitaire, word search and a game similar to Connect 4, or to complete another kind of brain training in which they had to strategically track objects and switch between tasks.

To explore how speed training may reduce dementia risk, the team collected blood samples from all of the participants at the start and end of the training period.

This revealed that, among men, speed training increased the ratio of two forms of beta-amyloid found in the blood, which suggests the training boosted the brainā€™s ability to clear beta-amyloid 42. This protein forms clumps called plaques in the brain during Alzheimerā€™s disease, disrupting brain function. The other two kinds of training had no effect.

ā€œItā€™s a really cool finding,ā€ saysĀ Ā at McGill University in Montreal. ā€œIt is definitely strengthening what theyā€™ve [previously] shown with the reduction in dementia.ā€

Some Alzheimerā€™s treatments, such as lecanemab, have been designed to help clear amyloid from the brain, but they only marginally slow cognitive decline during Alzheimerā€™s disease. The limited benefit seen in trials is probably down to these treatments being taken at a relatively late stage of the condition, when substantial brain damage has already occurred, says at University College London.

Engaging in cognitive training to reduce beta-amyloid build-up before dementia develops may have a bigger effect on dementia because it would be done before much brain damage has occurred, says Castegnaro.

However, cognitive training had no effect on amyloid levels in female participants in the study. This suggests that speed training reduces dementia risk in different ways in women and men, says Chai.

The team hopes to explore how speed training may benefit women in future studies, says Chai. But first, the findings need to be verified in geographically and ethnically diverse groups, says Novozhilova.

A combination of two drugs used to treat hay fever and psychosis cooled down the core body temperature of mice and monkeys, reducing brain damage after a stroke. These medications have also undergone preliminary testing in people, and will now be evaluated in a follow-up clinical trial.

Researchers have spent decades investigating ways to chill peopleā€™s brains after they have a stroke to try to limit the damage. The idea is to freeze brain cells in a hibernation-like state so they donā€™t need as much oxygen and glucose when a stroke cuts off their blood supply. If brain cells can be kept alive until blood flow is restored, for example, by removing a clot, a patient may be spared from extensive brain damage and related speech and movement problems.

Unfortunately, the physical cooling strategies that have been looked at so far ā€“ including cooling blankets, ice packs and helmetsĀ ā€“ havenā€™t worked well. This is because they cause intense discomfort and uncontrollable shivering, says at the University of Newcastle in Australia, who wasnā€™t involved in the study.

Shivering is one method the body uses to ā€œfight the induction of hypothermiaā€, making it hard to get body temperature down low enough, she says. ā€œItā€™s great to see different cooling therapies being tested out for stroke because we know that physical cooling is just not feasible,ā€ says Coupland.

Shuaili Xu at Capital Medical University in Beijing, China, and his colleagues administered the two drugs, promethazine and chlorpromazine, which have been known to reduce body temperature , to mice and rhesus monkeys following induced strokes.

In both animals, the drug combination led to drops in core body temperature, suppressed glucose metabolism in cells and lessened the amount of brain damage caused by the stroke. The reduced brain damage also meant the treated monkeys displayed better use of their limbs.

Free newsletter

Sign up to ĪēŅ¹ø£Ąū1000¼ÆŗĻ Check

Sign up to newsletter

Next, the team conducted a clinical trial involving 32 people who had just had a stroke. Upon hospital admission, the subjects were given the promethazine and chlorpromazine combination or a placebo, in addition to standard clot-removal therapy.

The promethazine and chlorpromazine treatment only reduced the patientsā€™ body temperature by 0.3Ā°C (about 0.5Ā°F) and did not reduce stroke damage. However, Xu thinks this is because the infusions were done over 12 hours, which was too slow to bring down core body temperature by a meaningful amount. ā€œIt might have led to a low blood drug concentration per unit of time,ā€ he says.

Ultrasound may boost survival after a stroke by clearing brain debris

The damage of strokes caused by brain bleeds can be mitigated by removing dead blood cells. Scientists have now found a way of doing this non-invasively, with promising results in mice

His team is now launching another trial to see whether faster infusions over an hour produce stronger cooling effects and therapeutic benefits. ā€œThe fact that theyā€™ve proven that itā€™s safe and these drugs are already used in humans for other indications means I think that itā€™s reasonable to proceed with further clinical trials,ā€ says Coupland.

Promethazine and chlorpromazine are known to be relatively safe because they have been used for decades. Promethazine is a sedating antihistamine that can ease hay fever and assist sleep, while chlorpromazine is an antipsychotic drug used in the management of schizophrenia and bipolar disorder. They both act on the central nervous system to reduce core body temperature, without translating into shivering or subjective feelings of coldness.