Brain Anatomy Irregularities

In the past decades, researchers have also noticed abnormalities in brain structure, particularly in people who suffer from the negative symptoms of schizophrenia.  Some of these abnormalities include:

Enlarged Ventricles

The brain has several hollow cavities within it that contain a nutrient rich fluid called the cerebrospinal fluid.  These cavities are called the ventricles.  The ventricles on the left side of the patient’s brain are much larger than the right ventricles.  People with schizophrenia who have enlarged ventricles tend to suffer from the negative symptoms, have poorer social adjustment prior to the onset of the disorder, have greater cognitive disturbances, and poorer responses to the traditional antipsychotics.  Studies also suggest that people with this disorder also have smaller frontal lobes (the part of the brain associated with rational thought, motivation, and decision making) and reduced blood flow to the entire brain.  It may be that the enlarged ventricles are the result of poor brain development or tissue damage in the area around them.  It may be that these problems are the ones that lead to the development of schizophrenia.  

This is an MRI scan of the brains of twins, one of whom has schizophrenia and one who does not. It clearly shows the enlarged ventricles, which are thought to be a causal factor in the development of schizophrenia.

Enlarged Corpus Callosum

The corpus callosum is the part of the brain that connects the two halves, or hemispheres.  It is responsible for relaying information back and forth between the two hemispheres.  In people with schizophrenia, it is thicker and longer, suggesting that the two hemispheres are not communicating well.  In an effort to compensate for the poor communication, the corpus callosum has gotten larger.

Hypofrontality

In patients suffering from schizophrenia, there is too little frontal lobe activation and too much occipital lobe action.  The frontal lobes are in the front part of the brain (behind the forehead) and are responsible for rational thought, motivation, decision-making, and information processing).  The occipital lobes are at the back of the head and receive input from the eyes.  The hypofrontality hypothesis states that too much stimulation is coming in and the frontal lobes cannot process it all.

Imaging studies have shown reduced volume and loss of tissue in the brains of people with schizophrenia, especially volume losses in the prefrontal cortex and in areas involving the limbic system and the temporal lobes. Prefrontal loss affects memory, attention, reasoning, aggression, and meaningful speech - all functions involved in negative symptoms. Temporal lobe volume loss affects the limbic areas, which contain the hypothalamus, amygdala, and hippocampus. This area is related to emotions and memory, and abnormalities are associated with positive symptoms like delusions and hallucinations. However, researchers have been unable to find signs of specific tissue or nerve damage that might be the source of schizophrenia. Some studies suggest that there are fewer than normal connections between nerve cells in patients with schizophrenia.

This is a PET scan comparing the brains of twins who are discordant for schizophrenia.  The brain on the left shows normal activation patterns, while the brain on the right, belonging to the twin with schizophrenia, is clearly abnormal.