THURSDAY, July 14, 2005 (HealthDay News) -- Everyone knows money can't buy happiness, and a new study suggests brains won't guarantee it, either.
Among 80-year-olds, "satisfaction with life in late adulthood was unrelated to IQ in either childhood or late adulthood," concludes one of the longest-running studies ever done on the subject, published in the July 16 issue of the British Medical Journal.
Researchers at the University of Edinburgh tracked the intelligence and emotional health of 550 Scots born in 1921. The participants were first given intelligence tests at age 11 and then once again more than six decades later at age 79.
The participants also were given the widely used "satisfaction with life" test, in which interviewees are asked to give an opinion, ranging from "strongly disagree" to "strongly agree" to such statements as, "In most ways, my life is close to ideal," and "If I could live my life over again, I would change almost nothing."
The result? By age 80, "correlations between the satisfaction with life scale and IQ at age 11 and age 79 were not statistically significant," the researchers report.
That result may surprise some people because "in today's society, mental ability is often highly valued," said co-researcher Alan J. Gow. He speculated that, "it might be that as long as people have enough intelligence to get by, anything above and beyond that may not be important."
The study found that intelligence has both an upside ("increasing one's resources through entry to better employment, for example,") and a downside ("awareness of alternative lifestyles or a striving for greater achievement"), both of which can contribute to -- or undermine -- happiness.
The result is a wash, Gow said, with intelligence ending up having "no association with happiness at all."
All of this came as no surprise to Colin Milner, chief executive officer of the International Council on Active Aging in Canada.
"What ends up happening is that as you grow older, what impacts your happiness is the quality of life you are living," Milner said. For example, he said, "If you are bedridden and not able to get around, that will be a decisive factor."
Happiness, or the lack of it, can be an important medical issue, he said. "The World Health Organization has stated that depression will be the second leading cause of premature death by 2020," Milner added.
In the end, intelligence is just one part of a complex picture, according to Milner. "Many other things have a huge impact on whether you are happy or not," he said. "Intelligence is one of the small elements."
For the latest in aging research, head to the Alliance for Aging Research.