Anaesthetic drug xenon prevents early death and long-term cognitive impairment in traumatic brain injury, in animal studies
Traumatic brain injury (TBI) is the leading cause of death and disability in people under 45, around the world. The primary injury is caused by the initial force from a fall or car accident and is followed by a secondary injury which develops in the next few days, which is largely responsible for the mental and physical disabilities associated with TBI.
Patients with TBI early in life are eight times more likely to die early than people without and are more likely to develop Alzheimer’s Disease and other types of dementia later on. There is currently no specific drug treatment available for people who suffer a TBI – instead, the treatment is supportive and rehabilitative.
Researchers have found that the anaesthetic drug xenon, given shortly after a TBI, prevents early death and long-term cognitive impairment and protects brain tissue itself in mice. The xenon-treated mice had a similar life expectancy, cognitive function, and brain tissue integrity, to mice that had never sustained a TBI.
Researchers have found that the anaesthetic drug xenon, given shortly after a TBI, prevents early death and long-term cognitive impairment and protects brain tissue itself in mice
This new study, published in the British Journal of Anaesthesia, looked at the effects of xenon over the whole lifespan of mice for the first time.
Animals were randomly allocated to one of three groups: TBI xenon, TBI control and healthy control. The healthy control group was given anaesthesia, but did not receive a TBI. The researchers gave xenon gas to one of these groups (TBI xenon group), while the other two received control gas for the same amount of time.
All three groups then underwent learning and memory tests at two weeks and 20 months after injury. The researchers also recorded their time of death and examined their brain tissues.
They found that:
- The TBI xenon group had the same life expectancy as the healthy control group which had not suffered a TBI.
- The TBI control group developed late-onset cognitive damage. Xenon treatment shortly after TBI appeared to prevent this.
- Key brain areas involved in cognitive functioning were damaged in control TBI group. Xenon-treatment prevented or significantly reduced this damage.
- Xenon prevented the loss of brain cells in the hippocampus (an area of the brain associated with learning and memory), and prevented degeneration of nerve fibres in the corpus callosum (which connects the two brain hemispheres) that may explain the improvement in cognitive function. Xenon was also shown to reduce long-term brain inflammation that is believed to be involved in cognitive impairment in Alzheimer’s Disease and other dementias.
“We have looked at very long-term outcomes, up to 20 months after TBI in mice. This is very rarely done in animal studies and is equivalent to following up human TBI patients until their 80s. The finding that only a short treatment with xenon can have beneficial effects on cognition, survival, and brain damage almost two years later suggests that xenon might in future prevent cognitive decline and improve survival in human TBI patients,” said Dr Robert Dickinson of Imperial College of London’s Department of Surgery & Cancer. Xenon is already used as a human general anaesthetic, is known to have few side effects and could be easily given via inhalation or to mechanically ventilated TBI patients in the intensive care unit. The researchers plan to evaluate the effectiveness of xenon in human TBI patients.
