Tests were carried out on 150 volunteers who weighed 21 stone plus and these were compared with healthy people.
Following the tests, two thirds of them has gastric by-pass surgery and lost an average of 3st. 8lb. And after 12 weeks took the same tests again.
In the group who had lost weight, the scores involving memory had been boosted, as well as improvements in organisational skills.
The results of 41 volunteers who declined obesity surgery declined further.
The researchers discovered, by using magnetic resonance imaging of the brain that obese people appeared to have damage to the organis substances around the nerve fibres responsible for chemical message communications.