Is Schizophrenia A Neurodevelopmental Disorder?

The research we have discussed suggests that schizophrenia occurs when ab­normal genes and environmental risk factors combine to cause brain dys­function. In the past two decades, several researchers— notably Drs Daniel Weinberger, Larry Seidman, and Patricia Goldman- Rakic— have concluded that schizophrenia is a neurodevelopmental brain disorder. This suggests that schizophrenia emerges because of the way the brain is built early in life. To understand this concept, consider brain disorders that do not have a neurodevelopmental origin but instead, come about because of the way the brain breaks down after it is developed. We call these disorders neurodegenerative be­cause the causes of the disease attack and degrade a normal brain. The senility of old age, which doctors call dementia, is a common example. When some people age, their brain is degraded by events such as many strokes or the rav­ages of Alzheimer’s disease. After a few years, a person who once functioned normally can no longer do simple tasks. Other examples are acquired brain syndromes, which occur after an injury to the head, and disorders due to the in­gestion of toxic substances (e.g., drugs, lead paint). In each of these cases, some external agent has acted on a normal brain to make it abnormal. In neurodevelopmental disorders, the brain does not develop (i.e., grow) prop­erly. In other words, it was never really normal to begin with. We know that genes contain the ‘blueprint’ for building the brain. For schizophrenia, this blueprint contains errors so that the brain is not ‘built’ correctly. Dr Patricia Goldman- Rakic suggested that certain brain cells in individuals with schizophrenia do not ‘migrate’ correctly during development. That is, normal brain development re­quires that cells locate themselves in the right spot and connect to one another in specific patterns. In schizophrenia, it may be that some cells are in the wrong place, some do not make necessary connections, and others make connections that should not be made. It is as if the blueprint for a home told the electrician to put the light switch for the kitchen in the living room.