d. Identical twins are relatively rare, expecially twins who are both diagnosed with schizophrenia. Further defending the theory, studies have shown that children with one parent diagnosed with schizophrenia have a ten percent chance of suffering from schizophrenia. When both parents are schizophrenic their risk raises to about forty percent. Very little is known about the Environmental Theory. It is built mainly on the effects stress has on human behavior, however, most researchers agree that stress alone cannot be the main cause of schizophrenia. Most researchers agree that stress can trigger or worsen the symptoms when the illness is already present. Other researchers focus on drug abuse. Like stress, certain drugs such as amphetamines can make psychotic symptoms worse if a person already has schizophrenia. Furthermore, these drugs can create schizophrenia – like symptoms in normal persons when the dosage is large.Other researchers that support the Environmental Theory believe that “slow viruses” may be to blame. Slow viruses are viral infections that go undetected for long periods of time therefore signs and symptoms are delayed and may occur many years after the first infection. The Bio-Chemical Theory suggests that schizophrenia is caused by mixed up signals to the brain. When something acts upon on of our senses, electrical impulses are sent to the brain. These impulses allow us to feel pain, smell, and they also manage our thought processes. In our body we have a complex nerve system. For example, there is no one single nerve that travels from our feet to our brain. Therefore, in order for information to be sent to the brain the nerves must interact with each other. Because the system is so complex it is possible for the signal to get mixed up. When this happens our brain may misinterpret the signal or may not receive it at all. If the signal does get mixed up on the way to the brain the make...
