ACT Science Test - Practice Test 4 — Flashcards

Questions below are based on the following passage:

Schizophrenia is a mental disorder that affects 24 million people across the world. It is characterized by symptoms such as confused thinking, hallucinations, cognitive decline, abnormal perception of reality, and reduced social activity. These symptoms are managed with anti-psychotic medications, but few that suffer from schizophrenia fully recover. The neurological underpinnings of schizophrenia are not well understood. There are a variety of anatomical and functional changes that have been observed in patients, including reduced frontal lobe volume, overactive dopamine receptors, and enlarged lateral ventricles. However, there is significant debate as to what causes these changes.    

Environmental Hypothesis    
One theory about schizophrenia is that environmental factors influence its development. For example, it has been found that people that grow up in with abusive parents or experience a childhood trauma have a significantly elevated risk for developing schizophrenia. Cannabis use has also been linked to the disease in those who are already at risk. Lastly, the environment that a developing fetus is exposed to in utero has been found to correlate to the disease. Fetuses that experienced periods of infection, hypoxia (low oxygen), or malnutrition are more likely to become schizophrenic later in life.    

Genetic Hypothesis    
It is also theorized that genetics plays a large role in the development of schizophrenia. Its heritability (how much of an influence genetics has in the development of a particular trait) has been estimated to be as high as 80%. Furthermore, having a first-degree relative affected by schizophrenia increases risk significantly. Studies have revealed that mutations in dysbindin and neuregulin genes may be important in these inheritance patterns.