Abstract
Schizophrenia is a psychotic disorder characterized by distortion of reality, disturbances of thought and language, and withdrawal from social contact. It can also result in cognitive disturbances. Cerebellar dysfunction, movement problems, and postural control are also among important problems of schizophrenia. Various factors are involved in the development of schizophrenia. In these factors, hereditary characteristics, environment, and brain structure and function are found to have an important role. Medical imaging techniques such as positron emission tomography (PET), diffusion tensor imaging (DTI), and magnetic resonance imaging (MRI) can help in studying the disease. This paper deals with some important aspects of schizophrenia and also gives future directions to do more research on schizophrenia.
Schizophrenia is a psychotic disorder characterized by distortion of reality, disturbances of thought and language, and withdrawal from social contact. This disorder can result in several symptoms including positive symptoms such as delusion and hallucinations, and negative symptoms such as anhedonia (an inability to experience pleasure), and social withdrawal. Patients of schizophrenia may also show movement problems. Sometimes movement problems can be found in infants, who have increased chances of developing schizophrenia later in life (Bernard & Mittal, 2014). Early diagnosis and treatment of schizophrenia is important for adults having higher chances of developing schizophrenia.
Researchers have reported that movement abnormalities are problems in voluntary muscle movements that are sometimes caused by dopaminergic dysfunction in the basal ganglia. These movement problems can be found before the onset of disease and remain during the course of the disease. Postural control is also an important problem in schizophrenia. Cerebellar dysfunction can also develop in schizophrenia. It has been reported that problems in cerebellar function can be related to poor postural control and movement abnormalities (Bernard & Mittal, 2014). Speech as well as language delay has also been reported in early-onset schizophrenia (Tiffin & Welsh, 2013).
Causes of schizophrenia
Various factors are involved in the development of schizophrenia. In these factors, hereditary characteristics, environment, and brain structure and function are found to have an important role.
Hereditary characteristics and environment
Researchers have reported that schizophrenia can run in families. Usually, 1% of the population is affected by this disorder, but its chances can be increased up to 10% in people, who has a direct relation to a schizophrenic patient. Moreover, chances of developing the disease also increase in people, who are indirectly related to a schizophrenic patient as, for example, if uncles, aunts, and/or cousins of a person have schizophrenia, chances of schizophrenia also increase in that person. Chances of developing the disease can increase by 40% to 65% in identical twins (National Institute of Mental Health, n.d.).
Researchers are of opinion that various genes are related to the development of schizophrenia, but no gene can cause the disease itself. Present research shows that rare genetic mutations are involved in the development of schizophrenia. These mutations can affect hundreds of genes, thereby disrupting the brain development. It has also been reported that malfunctions in some genes that are involved in the production of important brain chemicals can result in schizophrenia. These malfunctions may affect the higher functioning skills of the brain. However, prediction of the development of disease in later life with the help of genetic information is still not possible (National Institute of Mental Health, n.d.).
Researchers have also reported that interaction between genes and the environment is also responsible for the development of schizophrenia. Environmental factors may include malnutrition before birth, exposure to viruses, problems at the time of birth, and certain other psychosocial factors (National Institute of Mental Health, n.d.).
Brain structure and function
Researchers are of opinion that imbalances in the complex chemical structure and function of the brain have an important role in the development of schizophrenia. These imbalances can be related to neurotransmitters such as dopamine and glutamate. Neurotransmitters are related to the communication of brain cells. It has also been reported that brains of patients of schizophrenia are different in appearance than those of normal people as, for example, ventricles, fluid-filled cavities in the brain, are larger in some patients of schizophrenia as compared to normal people. Similarly, gray matter can also be reduced in patients of schizophrenia, and some parts of the brain may show more or less functionality (National Institute of Mental Health, n.d.).
Scientists have studied the brain tissues of schizophrenic patients after death, and found changes in the characteristics and distribution of brain cells that are thought to be occurred before birth. Based on these findings, it has been suggested that certain problems can develop during brain development that may not appear until puberty. During puberty, several changes take place in the brain that may stimulate the psychotic problems (National Institute of Mental Health, n.d.), thereby increasing the chances of schizophrenia in the mid-twenties (Tiffin & Welsh, 2013). Medical imaging studies can help in the study of schizophrenia as they can detect internal structures, which are usually affected by the chemicals in the brain.
Role of cerebellum. Cerebellum is an important part of the vertebrate brain that is located above the medulla oblongata and beneath the cerebrum in human beings. It is comparatively larger structure making about 10% of the entire brain volume, and is related to both motor as well as non-motor characteristics (Bernard & Mittal, 2014). Cerebellum is also involved in cognitive and affective processing.
Cerebellar activation deficits are found throughout the problem of schizophrenia. It has also been suggested that the detailed study of cerebellar structural and functional organization can help in studying the disease as distinctive cortico-cerebellar circuits and cerebellar regions can have different impact on the state of the patient having psychotic problems. Therefore, researchers have shown particular interest in the cerebellum, especially cerebello-thalamic connections of patients of schizophrenia (Bernard & Mittal, 2014).
In a study, it has been reported that the volume of anterior cerebellum and cerebellar vermis in patients of schizophrenia is smaller than normal people. Studies have also shown that patients of schizophrenia have decreased gyrification in the cerebellar vermis, reduced level of neuronal integrity, and reduced number of Purkinje cells as compared to controls. Purkinje cells are most important cerebellar cell types that are considered as the only source of output for the whole cerebellar cortex. It has been suggested that volumetric differences between controls and patients is due to reduced integrity of neurons and decreased number of Purkinje cells. However, these findings require further studies as there are mixed results as, for example, some studies have shown that cerebellar volume is increased in some patients of schizophrenia and decreased in other patients as compared to controls (Bernard & Mittal, 2014).
Role of other brain areas. Functional abnormalities have also been found in thalamus and cortex in patients with schizophrenia (Bernard & Mittal, 2014). Thalamus is present between cerebral hemispheres, and is related to the pain perception. Cortex is the outer layer of cerebrum that is involved in memory, perception, attention, and consciousness (Baars & Gage, 2012).
Imaging studies in Schizophrenia
Medical imaging techniques have helped a lot in working on differences in the cerebella and other parts of the brain of schizophrenic patients. With the help of positron emission tomography (PET), researchers have found that patients of schizophrenia show disturbed associative learning. It has also been found that there is a decreased blood flow in the thalamus and the cerebellum of patients of schizophrenia. This research is also showing that cerebellar function is disturbed in patients of schizophrenia along with certain behavioral disturbances (Bernard & Mittal, 2014).
With the help of diffusion tensor imaging (DTI), researchers looked at the structural connectivity of the cerebellum and found decreased white matter structural integrity in superior cerebellar peduncle in patients with motor sequencing deficits as compared to controls. On the other hand, in patients without deficits differences in the corticospinal tract have been found relative to controls. This is showing that there are some sub-groups within schizophrenia (Bernard & Mittal, 2014).
Researchers have also used magnetic resonance imaging (MRI) to study sequence learning in patients of schizophrenia. They studied volumes of the cerebellum and pre-supplementary motor area (SMA). It has been found that there were no group differences in total cerebellar volume between controls and patients. So, it has been suggested that disturbances in the measurement of the entire structure is responsible for schizophrenia (Bernard & Mittal, 2014).
Management of schizophrenia
Schizophrenia is usually treated with the help of antipsychotic medications along with psychological and social support. Antipsychotics may include risperidone, clozapine, olanzapine, and amisulpride. Clozapine is found to be more effective as compared to other drugs. However, all these drugs are associated with serious side effects such as acute dystonias (including painful spastic contraction of some muscles), tardive dyskinesia (including involuntary and purposeless movement of tongue, face, and extremities), and Parkinson-like symptoms (Burton, 2011). Many antipsychotic medications can also prolong QTc interval that may show ventricular tachyarrhythmias ultimately leading to death. Therefore, these are used with great precaution. One of the most important remedial strategies in reducing side effects is the reduction of antipsychotic dose. Another strategy is change in dietary lifestyle and increased physical activity that can help in reducing weight gain associated with antipsychotics. In order to decrease tremor as well as stiffness as a result of antipsychotics, anticholinergic medications can be used (Tiffin & Welsh, 2013).
Among other therapeutic strategies are electroconvulsive therapy (ECT) and transcranial direct current stimulation (tDCS). ECT is helpful in reducing symptoms of schizophrenia. tDCS is an alternative to ECT. It is safer than ECT as general anesthesia is not required for electromagnetism in this process. Although tDCS is effective in reducing hallucinations, it is still not available widely due to its bulky nature and high cost (Tiffin & Welsh, 2013).
On the other hand, psychosocial interventions may include family support and therapy, supportive community treatment, training of coping skills, and weight management. All these interventions can help reducing distress and improving recovery.
Concluding remarks and future directions
Schizophrenia is among the most important psychiatric problems in the world. Most of its symptoms are related to dysfunctional cerebellar activity. These cerebellar problems can result in movement disturbances, and can be found before the start of the disease. Imaging studies have helped in knowing the disorder but still further studies are required.
More research is required in motor learning in patients of schizophrenia. It has been reported that direct connection between movement disturbances, and functions of the cerebellum and/or cerebello-cortical networks need further studies (Bernard & Mittal, 2014). In this regard, latest advances in neuroimaging techniques and their combinations with the study of other movement disorders can help in taking the research to the next step. Cerebellar volume and/or function can also be utilized to investigate schizophrenia and related problems.
It is also important to note that most of the studies in the assessment and management of schizophrenia are related to adults. Children must also be studied; especially developmental differences have to be studied in children. It is quite possible that advancements in schizophrenic research in children could help in making advancements in reducing the incidences of schizophrenia in adults and treating it after its development.
References
Baars, B., & Gage, N. M. (2012). Fundamentals of Cognitive Neuroscience: A Beginner's Guide: Elsevier Science.
Bernard, J. A., & Mittal, V. A. (2014). Cerebellar-motor dysfunction in schizophrenia and psychosis-risk: the importance of regional cerebellar analysis approaches. Front Psychiatry, 5, 160. doi: 10.3389/fpsyt.2014.00160
Burton, N. (2011). Psychiatry: Wiley.
National Institute of Mental Health. (n.d.). Schizophrenia. Retrieved July 6, 2015, from http://www.nimh.nih.gov/health/topics/schizophrenia/index.shtml
Tiffin, P. A., & Welsh, P. (2013). Practitioner review: schizophrenia spectrum disorders and the at-risk mental state for psychosis in children and adolescents--evidence-based management approaches. J Child Psychol Psychiatry, 54(11), 1155-1175. doi: 10.1111/jcpp.12136
