Scientists claim to have identified a genetic manipulation that can boost the growth of brain cells linked to learning.

A team at the University of Texas has found that deleting the Nf1 gene in mice increases the development of neurons in the brain during ageing, which in turn, enhances the effect of anti depressant drugs.

"The significant implication of this work is that enhancing neurogenesis sensitises mice to antidepressants meaning they needed lower doses of the drugs to affect mood and also appears to have anti depressive and anti-anxiety effects of its own that continue over time," said Dr Luis Parada, a team member.

Just as in people, mice produce new neurons throughout adulthood, although the rate declines with age and stress, said Dr Parada.

In their research, the scientists used a sophisticated process to delete the gene that codes for the Nf1 protein only in the brains of mice, while production in other tissues continued normally.

After showing that mice lacking Nf1 protein in the brain had greater neurogenesis than controls, they administered behavioural tests designed to mimic situations that would
spark a subdued mood or anxiety, such as observing grooming behaviour in response to a small splash of sugar water.

The scientists found that the test group mice formed more neurons over time compared to controls, and that young mice lacking the Nf1 protein required much lower amounts of
anti depressants to counteract the effects of stress.

Behavioural differences between the groups persisted at three months, six months and nine months. "Older mice lacking the protein responded as if they`d been taking antidepressants all their lives.

"In summary, this work suggests that activating neural precursor cells could directly improve depression and anxiety like behaviours, and it provides a proof regarding
feasibility of regulating behaviour via direct manipulation of adult neurogenesis," Dr Parada said.