Alan Bernstein is the president and CEO of the Canadian Institute for Advanced Research and a Lawson Foundation fellow. He is the former executive director of the Global HIV Vaccine Enterprise and was the founding president of the Canadian Institutes of Health Research. He was recently inducted into the Canadian Medical Hall of Fame.
In the 1950s, the health issues that worried parents the most were viruses, especially the ones that caused polio and measles. Despite recent outbreaks, vaccines have largely eliminated these diseases from the North American population.
Now the big issues are obesity and eating disorders, drugs and mental health. There has been a sea change in the patterns of health problems affecting children, and our health system must change to meet these needs.
Seven per cent of children today suffer from a disability due to a chronic condition. That's almost a fourfold increase since 1960. These health challenges are less obvious and less immediate than the ones that faced us a half-century ago, but they are also more difficult to treat or prevent.
We now know that these chronic conditions have one thing in common: They are all the result of the complex interplay between the child's genetic makeup and the environment in which he or she is brought up. New research is providing important insights into the biology of how the environment gets "under the skin" of children, with implications for how we help prevent or treat this new pattern of disabilities affecting our children.
Take obesity. Robert Putnam, a professor of public policy at Harvard University and a former adviser at the Canadian Institute for Advanced Research (CIFAR), examined the statistics for obese children in the United States. The good news was that after years of constant increases, the number of obese children is starting to level off. The bad news is that only well-off children are more likely to be fit; obesity is still increasing among poor children.
Again and again we see that a challenging environment in childhood leads to suboptimal physical, mental and emotional health that lasts a lifetime. For example, Thomas Boyce, a CIFAR senior fellow at the University of California, San Francisco, showed that adults who had been poor as children were twice as likely to suffer from arthritis and hypertension as those who had not been poor, regardless of how well off they were as adults.
How do our early experiences give rise to these long-term consequences? An important part of the story centres around how our experience affects our genes. Although the DNA we're born with doesn't change, we now know that genes can be turned on or off by experience. These changes are called epigenetic changes.
Michael Meaney, a CIFAR senior fellow at McGill University, showed how this works in mice. Mice raised by neglectful mothers had a certain gene turned off, a condition associated with an increase in anxiety and stress that they experienced for the rest of their lives. Later, he found the same alteration in humans who had experienced neglect or abuse as children. These people literally carried the mark of their early experiences in the way their genes were expressed.
We're learning how and why children are vulnerable to difficult early environments. So what do we do about it? Ending poverty is a complex and challenging undertaking. But the research suggests additional approaches that could be effective.
We know that early adversity affects some children more than others. We may be on the verge of finding tests that can show which children have suffered the epigenetic changes that will lead to lifelong problems. We could then target those children for early interventions.
Ultimately, we might even be able to find treatments that reverse the epigenetic damage and restore to the child the full capacities they were always meant to have.
In the meantime, we know that the early years are a critical developmental window and affect what will happen decades later. It makes good public policy to provide an optimal environment for the most vulnerable members of our society – our children.