Scientists, however, do need to study causes in an effort to identify ways to prevent learning disabilities. Once, scientists thought that all learning disabilities were caused by a single neurological problem. But research supported by NIMH has helped us see that the causes are more diverse and complex. New evidence seems to show that most learning disabilities do not stem from a single, specific area of the brain, but from difficulties in bringing together information from various brain regions. Today, a leading theory is that learning disabilities stem from subtle disturbances in brain structures and functions.
Some scientists believe that, in many cases, the disturbance begins before birth.
The fact that learning disabilities tend to run in families indicates that there may be a genetic link. For example, children who lack some of the skills needed for reading, such as hearing the separate sounds of words, are likely to have a parent with a related problem. Possibly, what is inherited is a subtle brain dysfunction that can in turn lead to a learning disability. Research shows that a mother's use of cigarettes, alcohol, or other drugs during pregnancy may have damaging effects on the unborn child. In some cases, the mother's immune system reacts to the ferns and attacks it as if it were an infection.