A Genetic Look at Schizophrenia

Schizophrenia is a mental disorder that is seems many people have heard of, but few are actually informed about. In fact, the media does a good job of distorting schizophrenia into one disorder, when actually there are different classifications of schizophrenia. Similarly, there are a number of different explanations for the various degrees of the disorder. These different explanations come from different psychological schools of thought. From a biological standpoint comes a genetic explanation. While the biological viewpoint also offers biochemical and brain abnormality as an explanation for schizophrenia, only the genetic part shall be discussed here.

The biological viewpoint of schizophrenia focuses on genetic factors and molecular biological links. The aforementioned genetic factors have been studied in terms of twin studies and studies comparing adoptive and biological parents with their children. These types of studies help researchers determine either the genetic or environmental influence in the development of schizophrenia. Studies of identical and fraternal twins have found that if one in a set of identical twins develops schizophrenia, the other has a 48% chance of also developing the condition. In contrast, fraternal twins have only a 17% chance of developing schizophrenia if the other has the condition (Comer, 2005, pg 361). The significant correlation between identical twins seems to indicate a genetic link in the mystery of schizophrenia. Additionally, adoption studies have found genetic linkages in that biological relatives are more likely to develop schizophrenia than are adoptive relatives.

Despite this encouraging step toward the factors causing schizophrenia, there are still a great many questions surrounding this genetic link. The confusion has arisen from research that has indicated possible genetic defects on 11 different chromosomes; chromosomes 1, 5, 6, 8, 9, 10, 11, 13, 18, 19, and 22 (Comer, 2005, pg 362). Does this mean that a person with schizophrenia has 11 defective genes? Not exactly. What it does indicate, however, is that schizophrenia might be caused by a combination of genetic defects, as has been seen in a number of other disorders. It may indicate that different types of schizophrenia are caused by different genes and their defects. Lastly, the fact that 11 possible gene defects were located may also be an indication that some of these genes do not cause schizophrenia at all, instead they were mistakenly attributed to schizophrenia. Since there is still a great deal of research that needs to be completed before this genetic link can be explained with certainty, it seems that the aforementioned research into twins and biological versus adoptive parents is the best evidence of an affirmative genetic link.

Comer, R. J. (2005). Fundamentals of Abnormal Psychology, 4^th Ed. Worth Publishers, NY.