Lesson 1: Predisposition, Biological Factors, and the Brain

The world’s most complex construction project – building a human brain begins in a tiny sac tucked inside a woman’s body about six weeks after she conceives a baby. That is when primitive structures in the embryo start to churn out the first of billions of brain cells, known as neurons, which eventually will help determine if the infant is to be a kindly professor, a remorseless killer or something in between.

Recent dramatic advances in brain science show that the foundation of a child’s intellectual and emotional development is laid long before birth, indeed, even before he or she is conceived.

“Life in the womb will be written on your tomb,” Irina Pollard, an expert on the biology of children, said recently at a panel on the subject.

Furthermore, biologists and psychologists now believe that the first three years of life are even more important than previously realized. Well-intentioned remedial programs aimed at four and five year olds, come too late to do much good, according to Craig Ramey, a leading authority on early development at the University of Alabama, Birmingham. Making up for a bad start is not impossible, experts say, but it is much more difficult. One of the lessons is that prospective parents have a crucial responsibility to provide a safe environment for their future progeny.

Did the father-to-be drink or smoke? Did the expectant mother avoid pesticides and watch her diet? Do Mom and Dad talk and sing to their newborns? Researchers say these questions set the odds on whether a child will do well later in life.

A future father’s role is especially important, since a man’s sperm is more easily damaged than a woman’s egg, and flaws can be passed on to succeeding generations.

“Genetic abnormalities are more often linked with paternal than with maternal DNA damage,” Pollard said.

Although most children turn out all right, she cited studies indicating that babies born to parents who are smokers, heavy drinkers or drug users are smaller, more likely to be mentally retarded, and more prone to cancer and other diseases than the children of people with healthier lifestyles.

For example, about two births out of every 1,000 produces a mentally retarded child, worldwide statistics show. Among pregnant women who consume at least two alcoholic drinks a day, however, the rate ranges up to 59 per 1,000 almost 30 times as high.

Another recent discovery is an apparent parallel between intelligence and emotion.

As neurons develop, some put out branches to organs like the amygdala, an almond-shaped structure deep inside the brain that is associated with feelings such as anger and fear. Experts say a child’s ability to handle such feelings—as well as to read, think or do arithmetic—can be affected by neglect or abuse early in life. This helps understand why seven to 10 year-old kids who have had terrible experiences are able to commit heinous acts with no apparent remorse or concern for their victims, Ramey said.

“The evidence is scant, but it could be that their brains are fundamentally wired differently,” he added. “It drives home the importance of early intervention. Society’s welfare is at stake, not just the individual’s”.

Many insights flow from work with fruit flies, rats and monkeys, because animals can be put through experiments that would be impossible or unethical with human beings.

“Lower organisms tell us more than we ever believed about what’s happening in humans,” said Charles Epstein, a geneticist at the University of California, San Francisco. “Nature grabs a system that works and seems to retain it, all the way from fly to man.”

For example, William Greenough, a biologist at the University of Illinois, Champaign/Urbana, discovered that the brain cells of a young rat raised in a lively, complex environment, with mazes and plenty of company, have more branches and interconnections than a rat raised in an isolated cage.

The same principle probably applies to people, according to Dr. Norman Krasnegor, chief of the Human Learning and Behavior Branch at the National Center for Child Health and Human Development in Bethesda, Md.

“Early intervention can have a salutary effect on later development,” Krasnegor said. “Many people who live in poverty don’t understand how to interact with kids. They just feed them and hope they go to sleep.

In Ramey’s studies, he found that children from disadvantaged and normal families score about the same on mental tests until the age of 12 months. After that, however, kids from low-income or troubled homes start to develop at a slower rate. By 24 months, they are behind their better-off contemporaries by the equivalent of 15 points on the IQ scale.

“It’s a sleeper effect,” Krasnegor said.

Scientists are increasingly finding that mental disorders may only be malfunctions of the physical brain, much like a broken ankle, and perhaps, equally curable.

The brain is highly specialized, and mental maladies are rooted in specific areas of the brain. Anxiety disorders may affect areas of the brain that govern emotion; schizophrenia (affects) areas that govern hearing and sight.

“By knowing where in the brain things may go wrong in mental disorders, we can target rationally designed treatments,” said Steven Hyman, director of the National Institute of Mental Health.

“We’re actually beginning to localize specific emotions in the brain,” he said. One of the first: fear, based in an almond-shaped structure at the front of the brain. “This can help us to design better treatments for anxiety disorders,” Hyman said.

And brains, it turns out, don’t act all that different from the rest of our bodies. For instance, the things that keep bodies healthy, a balanced diet, rest and exercise, also keep the brain healthy.

Researchers also know that keeping intellectually active, or gaining high levels of education protects people against many brain disorders, the same way exercise helps physical health.

“Using your brain prevents disease,” said Joseph Coyle, chair of Harvard University’s department of psychiatry. “A use-it-or-lose-it strategy works in the brain.”

Hyman also expects the new understanding of the brain’s workings to pave the way to more acceptance for mental patients.

“Once we realize that mental disorders represent specific forms of brain functions,” he said, “the results should be profoundly destigmatizing.”