Being Happy Changes You

Why do happy people live longer?

The idea that an optimistic attitude causes people to live longer has been repeatedly observed. Although we identify our longevity to having “good” genes, only recently have we began to understand how our genes are affected by how happy we are.

The best way to study the effect of genetics on longevity is to look at twins. Monozygotic twins, those that split from one egg, have nearly similar genetic makeup. Twins that have a different egg (dizygotic) only share the same level of genotype as with any other siblings.

More than three decades ago, Cook and his associates published a study in 1981 looking at the onset of dementia among monozygotic twins who were both affected by Alzheimer's dementia. In one case study, dementia began in her late 60s, while in the other twin the onset of dementia was at age 83.

Subsequent studies confirm that although monozygotic twins might both have the disease, how they express them and when they express the disease might differ. The difference used to be attributed to the environment. But recent studies blurred the difference between genetics and the environment. 

Twelve years ago, in 2000, Randy Jirtle and Robert Waterlanda from Duke University modified the expression of an agouti gene that which made mice fat, yellow and prone to cancer and diabetes.  These mice did not live very long. The researchers produced young mice that were slender brown and without displaying their parents' susceptibility to cancer and diabetes and lived to an active old age. The effects of the agouti gene had been virtually erased.  

Remarkably, the researchers modified the expression of this gene not by altering the mouse's DNA, but by changing the moms' diet.  Feeding the mother a diet rich in onions, garlic, beets, and in the food supplements often given to pregnant women the researchers provided a chemical switch that reduced the agouti gene's harmful effects. 

These foods--known as methyl donors--enhance or diminish gene activation and gave birth to a whole new science of epigenetics. But can epigenetic changes influence longevity?

In 2012, Jordana Bell of King's College London and colleagues looked at the DNA of 86 sets of twin sisters aged 32 to 80, and repeated with another 44 sets of younger twins aged 22 to 61, and discovered that 490 genes linked with ageing showed signs of epigenetic change. In particular, among these malleable gene expression were four genes that relate to cholesterol, lung function and maternal longevity.

What is phenomenally interesting is that these changes are not just brought about by diet and methyl rich donors, but also by such lifestyle factors such as smoking, environmental pollution, stresses, and attitude.  So we might say that optimistic attitude allows your good genes to shine through while diminishing the effect of  your bad genes. And the effect jumps across generations. If you are long lived, thank your grandparents for being optimistic.

Mario Garrett, Ph.D., is a professor of gerontology at San Diego State University and can be reached at mariusgarrett@yahoo.com