A nicotine patch worn for six months can improve attention, memory and mental processing in people with mild cognitive impairment, a clinical trial has found.

Mild cognitive impairment, or MCI, involves a decline in mental acuity that is noticeable but not severe enough to be diagnosed as dementia. It is often a precursor to more severe disease.

Researchers randomly assigned 67 otherwise healthy men and women with MCI to wear a nicotine patch or a placebo patch for six months. The volunteers, non-smokers whose average age was 76, took periodic tests of mental ability, mood and behaviour.

Those with the nicotine patch showed improvements in reaction times, attention and long-term memory, and more modest improvements in short-term memory. For subjects on the placebo, scores declined on those tests.

Dr Paul A Newhouse of Vanderbilt University, the lead author, said there is good evidence that nerve cells that regulate attention have nicotine receptors. Still, the authors acknowledge that the sample was small, and there is no information on long-term progression.

Dr Newhouse warned that no one should start using a nicotine patch in the hope that it will improve memory.

Several of the authors of the study, published recently in Neurology, have received payments from pharmaceutical companies.