Damage to brain from smoking can be reversed
But study of thinning grey matter warns that repair could long process after quitting

Damage to the brain's outer layer caused by smoking may be reversible after quitting, but it could take years, a study said.
Brain scans of 500 Scottish septuagenarians confirmed a link between smoking and an acceleration of age-related thinning of the cortex - the outer layer of grey matter.
But the study also pointed, for the first time, to a potential for recovery after quitting.
The cortex of ex-smokers in the group "seems to have partially recovered for each year without smoking," the multinational research team wrote in the Nature journal Molecular Psychiatry. But they warned that it could be a long process.
Many studies have linked cigarette smoking with cognitive decline and dementia, and some also with brain degeneration.
"Evidence suggests that smokers have, on average, slightly poorer global cognitive functioning in later life, as well as lower mean scores on several cognitive domains such as cognitive flexibility and memory," said the study authors.
The team used people who had participated in the Scottish Mental Survey as school children in 1947, when their cognitive function was tested.