Schizophrenia Spectrum and Other Psychotic Disorders

Introduction to Schizophrenia and Psychosis

Schizophrenia is a disorder of psychosis in which the person’s thoughts, perceptions, and behaviors are out of contact with reality.

Defining Psychosis and Schizophrenia

Schizophrenia is a psychological disorder characterized by major disturbances in thought, perception, emotion, and behavior. About 1% of the population experiences schizophrenia in their lifetime, and usually the disorder is first diagnosed during early adulthood (early to mid-20s). Most people with schizophrenia experience significant difficulties in many day-to-day activities, such as holding a job, paying bills, caring for oneself (grooming and hygiene), and maintaining relationships with others. Schizophrenia is considered a disorder of psychosis, or one in which the person’s thoughts, perceptions, and behaviors are impaired to the point where they are not able to function normally in life. In informal terms, one who suffers from a psychotic disorder (that is, has a psychosis) is disconnected from the world in which most of us live.

Symptoms of Schizophrenia

Schizophrenia has a wide range of symptoms, and not all symptoms may be present in all forms of schizophrenia. The signs and symptoms of schizophrenia are usually divided into two categories: positive and negative. A third category of cognitive symptoms is also included in some descriptions of the disease. Both positive and negative symptoms are further characterized as motor, behavioral, and mood disturbances.

Positive Symptoms

Positive symptoms are disorders of commission, meaning they are something that individuals do or think. Examples include hallucinations, delusions, and bizarre or disorganized behavior. Positive symptoms can also be described as behavior that indicates a loss of contact with the external reality experienced by non-psychotic individuals. An example of a positive motor disturbance would be catatonic excitement, which is uncontrolled and aimless motor activity. Positive symptoms tend to be the easiest to recognize.

Hallucinations, one of the most noted symptoms, involve perceiving a sensory stimuli that no one else is able to perceive. Most frequently, people with schizophrenia hear voices that tell them what to do, warn of danger, or talk to each other about the individual. Delusions are also commonly experienced; they include false beliefs that are not of the culture of the individual and are unchanging even after being proven incorrect.

Negative Symptoms

Negative symptoms are disorders of omission, meaning they are things that the individual does not do. Examples include alogia (lack of speech), flat affect (lack of emotional response), anhedonia (inability to experience pleasure), asociality (lack of interest in social contact), avolition (lack of motivation), and apathy (lack of interest). Some individuals will experience a catatonic stupor, or a state in which they are immobile and mute, yet conscious. They may exhibit waxy flexibility, where another person can move the patient's limbs into postures and the patient will retain these postures, like a wax doll. In some cases, negative symptoms can be misinterpreted as depression or laziness.

Cognitive Symptoms

Cognitive symptoms are the most harmful to the livelihood of the individual, as they prevent the individual from participating effectively in the workplace or in society. Cognitive symptoms are subtle differences in cognitive ability that are normally only discovered after neuropsychological tests are given. These include poor ability to absorb and act upon information (executive functioning), lack of attention, and an inability to utilize working memory.

Motor Disturbances

Motor disturbances include disorders of mobility, activity, and volition. People with schizophrenia can exhibit too little (negative) or too much (positive) movement. In addition to catatonic stupor and catatonic excitement, examples of motor disturbances include stereotypy (repeated, non-goal directed movement such as rocking), mannerisms (normal, goal-directed activities that appear to have social significance, but are either odd in appearance or out of context, such as repeatedly running one's hand through one's hair or grimacing), mitgehen (moving a limb in response to slight pressure, despite being told to resist the pressure), ecopraxia (the imitation of the movements of another person), and automatic obedience (carrying out simple commands in a robot-like fashion).

Behavioral Disturbances

Disorders of behavior may involve deterioration of social functioning, such as social withdrawal, self-neglect, or neglect of environment. Behavioral disorders may also involve behaviors that are considered socially inappropriate, such as talking to oneself in public, obscene language, or inappropriate exposure. Substance abuse is another disorder of behavior; patients may abuse cigarettes, alcohol, or other substances. Substance abuse is associated with poor treatment compliance, and may be a form of self-medication.

Mood Disturbances

Disorders of mood and affect include affective flattening, which is a reduced intensity of emotional expression and responsiveness that leaves patients indifferent and apathetic. Typically, one sees unchanging facial expression, decreased spontaneous movements, a lack of expressive gestures, poor eye contact, lack of vocal inflections, and slowed speech. Anhedonia, or the inability to experience pleasure, is also common, as is emotional emptiness. Patients may also exhibit inappropriate affect, such as laughing at a funeral.

Treatment

The primary treatment of schizophrenia is antipsychotic medications, often in combination with psychological and social supports. Hospitalization may occur for severe psychotic episodes either voluntarily or (if mental health legislation allows it) involuntarily. Community support services—such as drop-in centers, visits by members of a community mental-health team, supported employment, and support groups—are common. Some evidence indicates that regular exercise has a positive effect on the physical and mental health of those with schizophrenia. A number of psychosocial interventions may be useful in the treatment of schizophrenia, including family therapy, skills training, and psychosocial interventions for substance abuse. Family therapy or education, which addresses the whole family system of an individual, may reduce relapses and hospitalizations.

The Schizophrenia Spectrum

The spectrum of psychotic disorders includes schizophrenia, schizoaffective disorder, delusional disorder, and catatonia.

In the previous version of the DSM (the DSM-IV-TR), schizophrenia was divided into five subtypes:

catatonic, disorganized, paranoid, undifferentiated, and residual. The purpose of defining these subcategories was to better predict what course a certain presentation of schizophrenia might take and what treatment options would be most effective. However, these subtypes have since been removed in the new DSM-5 (largely because their were not as useful as was hoped). Instead, schizophrenia is now understood as existing along a spectrum of psychotic disorders that include schizoaffective disorder, delusional disorder, and catatonia.

Schizophrenia

Schizophrenia is a psychological disorder characterized by major disturbances in thought, perception, emotion, and behavior. In order to be diagnosed with schizophrenia, according to the DSM-5, a person must exhibit both a psychotic episode and two additional symptoms for most of one month, and their symptoms must have a significant impact on social or occupational functioning for at least six months. The "two additional symptoms" can be delusions, hallucinations, disorganized speech, or a negative symptom or severely disorganized or catatonic behavior. If delusions or hallucinations or severe, only one symptom may be sufficient for diagnosis.

Schizoaffective Disorder

Schizoaffective disorder is characterized by abnormal thought processes and dysregulated emotions. A person with this disorder has features of both schizophrenia and a mood disorder (either bipolar disorder or depression) but does not strictly meet the diagnostic criteria for either. The bipolar subtype is distinguished by symptoms of mania, hypomania, or mixed episodes; the depressive subtype is distinguished by symptoms of depression only. Common symptoms of schizoaffective disorder include hallucinations, paranoid delusions, and disorganized speech and thinking.

The DSM-5 distinguishes schizoaffective disorder from psychotic depression or psychotic bipolar disorder by additionally requiring that a psychotic condition must last for at least two continuous weeks without mood symptoms (although a person may be mildly depressed during this time). Two episodes of psychosis (an increase from one episode in the DSM-IV) must be experienced in order for the person to qualify for this diagnosis.

Delusional Disorder

Delusional disorder is a psychiatric condition in which the person presents with delusions but no accompanying hallucinations, thought disorder, mood disorder, or significant flattening of affect. Apart from their delusions, people with delusional disorder may continue to socialize and function normally; their behavior does not stand out as odd or bizarre. However, their preoccupation with delusional ideas can disrupt their lives.

There are 7 subtypes of delusional disorder:

1. Erotomanic type (erotomania): Delusion that another person, often a prominent public figure, is in love with the individual.
2. Grandiose type: Delusion of inflated worth, power, knowledge, or identity.
3. Jealous type: Delusion that the individual's sexual partner is unfaithful when such is not the case.
4. Persecutory type: Delusion that the person (or someone the person is close to) is being treated badly or malevolently.
5. Somatic type: Delusion that the person has some physical defect or medical condition.
6. Mixed type: Delusions with characteristics of more than one of the above types but with no single predominant theme.
7. Unspecified type: Delusions that cannot be clearly classified into any of the subcategories.

To be diagnosed with a delusional disorder, the individual's delusions must last for at least one month and cannot be due to the effects of a drug, medication, or general medical condition. Delusional disorder cannot be diagnosed in an individual previously correctly diagnosed with schizophrenia. Auditory and visual hallucinations cannot be prominent, though olfactory or tactile hallucinations related to the content of the delusion may be present.

Catatonia

Broadly speaking, catatonia is any condition of abnormal motor activity thought to be caused by a psychiatric disorder. For example, individuals with schizophrenia can demonstrate manic patterns of repetitious movement with no purpose, compulsively mimic the sounds or movements of others, or maintain the same posture for a long period of time without moving. In the DSM-5, catatonia is not recognized as its own disorder but rather is listed as a symptom of other psychiatric conditions, such as schizophrenia, bipolar disorder, post-traumatic stress disorder, and depression.

Etiology of Schizophrenia

While genetics, environment, neurobiology, and psychosocial stress contribute to schizophrenia, the exact cause of the disease is unknown.

Schizophrenia is a severe neuro-psychiatric disease that affects approximately 1% of the world's population. It is characterized by a wide variety of symptoms that include both positive symptoms (such as hallucinations and delusions) and negative symptoms (such as lack of emotion or motor control). While many factors have been associated with developing schizophrenia—including genetics, early environment, neurobiology, and psychological and social processes—the exact cause of the disease is unknown.

Genetic Factors

With the advancement of scientific measures such as whole genome sequencing, researchers are able to better understand the genetic factors associated with schizophrenia. Scientists have discovered specific genes (such as VIPR2) and genetic mutations (including copy number variation, or CNV) that are directly related to the disease.

If an individual has a family member with schizophrenia, they are more at risk for developing the disorder than an individual without a family history of the disease. Concordance rates, or the frequency of an individual developing schizophrenia if a relative suffers from it, are remarkably high. Identical twins show a 50% concordance rate; individuals with two parents with the disease show a 40% rate; fraternal twins show a 12%–15% rate; individuals with one schizophrenic parent show a 12% rate; and individuals with a schizophrenic non-twin sibling show an 8% rate of also having the disease. In contrast to this, the general population has a 1% chance of developing the disease.

These rates indicate that the disorder is largely inherited, but they also suggest that additional factors influence the development of schizophrenia. It is generally thought that individuals can be predisposed to schizophrenia through genetic vulnerability, which is then triggered by environmental stimuli. Most researchers agree that both genetic vulnerability and environmental triggers must be present for the disease to develop.

Environmental Factors

While the exact environmental trigger(s) that influence the development of schizophrenia are unknown, scientists suspect that prenatal exposure to the flu or famine, obstetric complications, central-nervous-system infections in early childhood, and psychosocial stress in childhood and early adulthood may be linked to the disease.

Psychosocial environmental stressors can range from parental divorce to suffering from childhood abuse. Individuals who later develop schizophrenia may also be more socially anxious and have emotional fluctuations. It is unclear if these factors exacerbate stressors, are the result of these stressors, or stem from a third variable.

The pathenogenic theory of schizophrenia suggests that in-utero exposure to pathogens that affect the central nervous system may cause a predisposition for the development of schizophrenia.

It has been noted that people with schizophrenia often come from families with a low socioeconomic status. Some theorists suggest environmental stress associated with lower-class living may affect brain development, triggering the disease in genetically susceptible individuals. However, the correlation between socioeconomic status and schizophrenia could also be explained by the "downward drift" theory. This theory posits that because people with schizophrenia cannot hold a job or function well in society untreated, they "drift down" to a lower status.

While much research has been done regarding whether childhood experiences play a significant role in the development of schizophrenia, not much has been determined at this time.

Neurological Factors

Research has shown that neurotransmitter activity is significantly related to schizophrenia. The study of neurotransmitters and schizophrenia is particularly important because most of the pharmaceutical treatment options for the disease involve regulating these chemicals.

The Dopamine Theory of Schizophrenia

The dopamine hypothesis of schizophrenia is a model used by scientists to explain many schizophrenic symptoms. The model claims that a high fluctuation of levels of dopamine can be responsible for schizophrenic symptoms. The simplest version of this theory suggests that schizophrenia is associated with an increase of dopamine in the central nervous system.

Additional research has identified two dopamine pathways in particular that are associated with the positive and negative symptoms of schizophrenia. The first is the mesolimbic system, which affects areas regulating reward pathways and emotional processes; the second is the mesocortical system, which affects the prefrontal cortex, areas that regulate cognitive processing, and areas involved with motor control. Excess activity in the mesolimbic pathway and lack of activity in the mesocortical pathway are thought to be responsible for positive and negative symptoms, respectively.

The dopamine hypothesis has helped progress the development of antipsychotics, which are drugs that stabilize positive symptoms by blocking dopamine receptors. The fact that these medications have been shown to treat psychosis supports the dopamine theory.

Other Neurotransmitters

Dopamine is not the only neurotransmitter associated with schizophrenia, although it can be argued that it is the most studied. Seratonin and glutamate have also been linked with schizophrenia. Increased levels of seratonin are associated with positive symptoms. Glutamate has been theorized to exacerbate hyperactivity and hypoactivity in dopamine pathways, affecting both positive and negative symptoms.

Brain Areas Associated with Schizophrenia

In addition to neurotransmitters, specific neural circuitry in various areas of the brain has been linked to schizophrenia. Disregulation of neurotransmitters in the association cortex may explain why people with schizophrenia are not able to properly sort or filter information. The medial temporal lobe and hippocampus are associated with symptoms such as lack of focus and emotional regulation. The thalamus can also affect symptoms in various ways: a decrease in the size of the thalamus may lead to hallucinations, and a breakdown in one of the neural pathways within the thalamus is associated with disjointed associations. Finally, the basal ganglia also affect schizophrenia. This area is involved with the integration of information from cortical areas and may also influence disjointed perceptions of environmental information.