A high level of intelligence is no guarantee of happiness in old age, a new study has found.
Happiness in old age is not related to IQ, the study says.
Researchers from Edinburgh University looked at 550 Scottish volunteers born in 1921 who had their IQs tested when they were 11 and again at 80 years old.
They found no relation between their level of satisfaction with life and IQ, either in childhood or old age.
More intelligent people get better life opportunities but also have higher expectations, the report said.
The researchers, led by Professor Ian Deary from the University of Edinburgh, wrote in the British Medical Journal that higher ability could increase a person's resources through entry to better employment.
However, it could also bring an awareness of alternative lifestyles or a striving for greater achievement, they said.
These may be used when judging "subjective wellbeing".
It was possible that if people have enough mental ability for important aspects of their lives, individual differences do not matter much, the scientists added.
Prof Deary said: "If you are 80 and healthy, then your satisfaction with how your life has turned out bears no relation to how you scored on an IQ test recently or 70 years ago."