People with a low sense of self worth are more likely to suffer from memory loss as they get older, say researchers.
The study, presented at a conference at the Royal Society in London, also found that the brains of these people were more likely to shrink compared with those who have a high sense of self esteem.
Dr Sonia Lupien, of McGill University in Montreal surveyed 92 senior citizens over 15 years and studied their brain scans.
She found that the brains of those with low self-worth were up to a fifth smaller than those who felt good about themselves.
These people also performed worse in memory and learning tests.
Dr Lupien believes that if those with a negative mind set were taught to change the way they think they could reverse their mental decline.
He said: "This atrophy of the brain that we thought was irreversible is reversible - some data on animals and some data on humans shows that that if you enrich the environment if you change some factors this brain structure can come back to normal levels"
Researchers are studying which psychological treatments work best.
According to Dr Felicia Huppert of Cambridge University - the early signs are that fairly simple techniques can have an enormous impact:
"There are interventions which talk about focusing on positive things in everyday life and savouring good moments even at times when life is difficult little tiny things may give you pleasure so there are skills involved in how to derive pleasure from the ordinary things in life".
According to Dr Lupien, the fear of memory loss may be a self fulfilling prophesy as anxiety leads to negative thinking which leads to mental impairment.
"If you always think it's normal to lose something, then you will never work to increase it because doctors have always told you that. I'm saying that it is not normal.
"So this might impact positvely on the public by saying that its possible to impact on increasing your memory performance and by saying that it is normal to have a fulfilling life, we may be able to increase self esteem among the general public - and prevent a lot of these deficits related to age".