Biological Explanations
Structural Abnormalities in the Brain
Neuroanatomy
- The brain is split into three main sections, the cerebellum, cerebrum and brainstem.
- The cerebellum is tucked underneath the cerebrum and is involved in motor control, while the
brain stem regulates automatic processes such as breathing, while also connecting the brain to
other parts of the body.
- The cerebrum is the main part of the brain. It is made up of a thick top layer called the cortex as
well as subcortical regions.
- The cortex is made up from a layer of neurons around 2-4mm thick and is folded many times,
giving it a huge surface area.
- The cerebrum is split into two hemispheres, and these into four lobes; frontal, temporal,
occipital and parietal.
- Underneath the cortex are many subcortical regions, such as the limbic system which is made up
of the thalamus, amygdala and hippocampus.
- The two hemispheres are connected by the corpus callosum, which enables communication.
- The brain contains a number of cavities called ventricles, which are filled with cerebrospinal
fluid.
- Ventricles supply the brain with nutrients and help with the removal of waste, as well as applying
internal pressure to keep neurons in place.
- When the brain is damaged or injured, the ventricles enlarge to maintain the pressure that is lost
when neurons are destroyed.
Structural Abnormalities
- Schizophrenia was originally viewed as solely psychological and was thus treated with therapy and
psychoanalysis.
- However, when it became apparent that certain drugs could alleviate certain symptoms,
biological factors in the disease were taken seriously.
- Post-mortem studies and brain scans have demonstrated the possibility of structural differences
between the brains of schizophrenics and non-schizophrenics.
Brain Ventricles
- A number of studies suggest that schizophrenics have larger brain ventricles than non-
schizophrenics.
- Weinberger et al. (1979): CAT scan results showed that ventricular size in 58 schizophrenic
individuals was greater than that of 56 controls.
- Andreasen (1988): MRI scans showed that schizophrenics had ventricles 20-50% larger than non-
schizophrenics. It did not matter how long they had suffered from schizophrenia or the type of
medication they were taking.
- Brain ventricles enlarge when brain damage occurs, so these finding suggest damage to
schizophrenic brains.
- Suddath et al. (1990): In monozygotic twins, where one was schizophrenic and the other wasn’t,
the schizophrenic had enlarged ventricles and a reduced anterior hypothalamus. The
hypothalamus controls body temperature, the circadian rhythm and mediates emotional
responses.
- Torrey (2002): Ventricles of schizophrenics are approximately 15% larger, particularly in those
who suffer from significant negative symptoms.
Prenatal Development
- Susser et al. (1996): children conceived during a famine had twice the normal risk of developing
schizophrenia, thus pointing towards neurodevelopmental nutritional deficiency as a factor.
- Warner (1994): structural abnormalities in the brains of some schizophrenic indicate prenatal
trauma such as the mother having a viral infection, taking drugs or having a complicated delivery.
- Wright et al. (1999): there was an elevated risk of schizophrenia in children whose mothers had
flu during pregnancy.
- These factors all suggest that brain damage is a predisposing factor in the development of
schizophrenia, in other words, this research suggests that it is neurodevelopmental.
- Disanto et al. (2012): in a study of 60,000 English patients diagnosed with schizophrenia, bipolar
and depression, it was found that those born in January were statistically more likely to be
diagnosed with schizophrenia than those born from July to September. Research suggests that the
