Schizophrenia
Schizophrenia is a mental disorder characterized variously by hallucinations, delusions, disorganized thinking or behavior, and flat or inappropriate affect. Symptoms develop gradually and typically begin during young adulthood and rarely resolve. There is no objective diagnostic test; diagnosis is based on observed behavior, a psychiatric history that includes the person's reported experiences, and reports of others familiar with the person. For a formal diagnosis, the described symptoms need to have been present for at least six months or one month. Many people with schizophrenia have other mental disorders, especially mood, anxiety, and substance use disorders, as well as obsessive–compulsive disorder.
About 0.3% to 0.7% of people are diagnosed with schizophrenia during their lifetime. In 2017, there were an estimated 1.1 million new cases and in 2022 a total of 24 million cases globally. Males are more often affected and on average have an earlier onset than females. The causes of schizophrenia may include genetic and environmental factors. Genetic factors include a variety of common and rare genetic variants. Possible environmental factors include being raised in a city, childhood adversity, cannabis use during adolescence, infections, the age of a person's mother or father, and poor nutrition during pregnancy.
About half of those diagnosed with schizophrenia will experience a marked improvement over the long term with no further relapses, and a small proportion of these will recover completely. The other half will have a lifelong impairment. In severe cases, people may be admitted to hospitals. Social problems such as long-term unemployment, poverty, homelessness, exploitation, and victimization are commonly correlated with schizophrenia. Compared to the general population, people with schizophrenia have a higher suicide rate and more physical health problems, leading to an average decrease in life expectancy by 20 to 28 years. In 2015, an estimated 17,000 deaths were linked to schizophrenia.
The mainstay of treatment is antipsychotic medication, including olanzapine and risperidone, along with counseling, job training, and social rehabilitation. Up to a third of people do not respond to initial antipsychotics, in which case clozapine is offered. A network meta-analysis of 15 antipsychotic drugs found that all were more effective than placebo for schizophrenia, with clozapine showing the highest efficacy; side effect profiles differ substantially across drugs. In situations where doctors judge that there is a risk of harm to self or others, they may impose short involuntary hospitalization. Long-term hospitalization is used on a small number of people with severe schizophrenia. In some countries where supportive services are limited or unavailable, long-term hospital stays are more common.
Signs and symptoms
Schizophrenia is a mental disorder characterized by significant alterations in perception, thoughts, mood, and behavior. Symptoms are described in terms of positive, negative, and cognitive symptoms. The positive symptoms of schizophrenia are the same for any psychosis and are sometimes referred to as psychotic symptoms. These may be present in any of the different psychoses and are often transient, making early diagnosis of schizophrenia problematic. Psychosis noted for the first time in a person who is later diagnosed with schizophrenia is referred to as a first-episode psychosis.Positive symptoms
Positive symptoms are those symptoms that are not normally experienced, but are present in people during a psychotic episode in schizophrenia, including delusions, hallucinations, and disorganized thoughts, speech and behavior or inappropriate affect, typically regarded as manifestations of psychosis. Hallucinations occur at some point in the lifetimes of 80% of those with schizophrenia and most commonly involve the sense of hearing, but can sometimes involve any of the other senses such as taste, sight, smell, and touch. The frequency of hallucinations involving multiple senses is double the rate of those involving only one sense. They are also typically related to the content of the delusional theme. Delusions are bizarre or persecutory in nature. Distortions of self-experience such as feeling that others can hear one's thoughts or that thoughts are being inserted into one's mind, sometimes termed passivity phenomena, are also common. The type and content of auditory and visual hallucinations appears to be influenced, at least in part, by cultural and religious factors. Patients in the United Kingdom and United States are more likely to report hearing criticisms and commands; patients in Africa, Asia, and the Middle East report more religious messaging in their hallucinations. This is true even among transplants to these countries, suggesting these differences are cultural, and not genetic. Positive symptoms generally respond well to medication and become reduced over the course of the illness, perhaps linked to the age-related decline in dopamine activity.Negative symptoms
Negative symptoms are deficits of normal emotional responses, or of other thought processes. The five recognized domains of negative symptoms are: blunted affect – showing flat expressions or little emotion; alogia – a poverty of speech; anhedonia – an inability to feel pleasure; asociality – the lack of desire to form relationships, and avolition – a lack of motivation and apathy. Avolition and anhedonia are seen as motivational deficits resulting from impaired reward processing. Reward is the main driver of motivation and this is mostly mediated by dopamine. It has been suggested that negative symptoms are multidimensional and they have been categorised into two subdomains of apathy or lack of motivation, and diminished expression. Apathy includes avolition, anhedonia, and social withdrawal; diminished expression includes blunt affect and alogia. Sometimes diminished expression is treated as both verbal and non-verbal.Apathy accounts for around 50% of the most often found negative symptoms and affects functional outcome and subsequent quality of life. Apathy is related to disrupted cognitive processing affecting memory and planning, including goal-directed behaviour. The two subdomains have suggested a need for separate treatment approaches. A lack of distress is another noted negative symptom. A distinction is often made between those negative symptoms that are inherent to schizophrenia, termed primary; and those that result from positive symptoms, from the side effects of antipsychotics, substance use disorder, and social deprivation, termed secondary negative symptoms. Negative symptoms are less responsive to medication and the most difficult to treat. However, if properly assessed, secondary negative symptoms are amenable to treatment. There is some evidence that the negative symptoms of schizophrenia are amenable to psychostimulant medication, although such drugs have varying degrees of risk for causing positive psychotic symptoms.
Scales for specifically assessing the presence of negative symptoms, and for measuring their severity, and their changes have been introduced since the earlier scales such as the PANNS that deals with all types of symptoms. These scales are the Clinical Assessment Interview for Negative Symptoms, and the Brief Negative Symptom Scale also known as second-generation scales. In 2020, ten years after its introduction, a cross-cultural study of the use of BNSS found valid and reliable psychometric evidence for its five-domain structure cross-culturally. The BNSS can assess both the presence and severity of negative symptoms of the five recognized domains and an additional item of reduced normal distress. It has been used to measure changes in negative symptoms in trials of psychosocial and pharmacological [|interventions].
Cognitive symptoms
An estimated 70% of those with schizophrenia have cognitive deficits, and these are most pronounced in early-onset and late-onset illness. These are often evident long before the onset of illness in the prodromal stage, and may be present in childhood or early adolescence. They are core features but not considered core symptoms, as are positive and negative symptoms. However, their presence and degree of dysfunction are taken as better indicators of functionality than the presentation of core symptoms. Cognitive deficits become worse at first episode psychosis but then return to baseline, and remain fairly stable over the course of the illness.Cognitive deficits may be of neurocognition or of social cognition. Neurocognition is the ability to receive and remember information, and includes verbal fluency, memory, reasoning, problem solving, speed of processing, and auditory and visual perception. Verbal memory and attention are seen to be the most affected. Verbal memory impairment is associated with a decreased level of semantic processing. Another memory impairment is that of episodic memory. An impairment in visual perception that is consistently found in schizophrenia is that of visual backward masking. Visual processing impairments include an inability to perceive complex visual illusions. Social cognition is concerned with the mental operations needed to interpret, and understand the self and others in the social world. This is also an associated impairment, and facial emotion perception is often found to be difficult. Cognitive impairments do not usually respond to antipsychotics, and there are a number of interventions that are used to try to improve them; cognitive remediation therapy is of particular help.
Neurological soft signs of clumsiness and loss of fine motor movement are often found in schizophrenia, which may resolve with effective treatment of FEP.
Onset
Onset typically occurs between the late teens and early 30s, with the peak incidence occurring in males in the early to mid-twenties, and in females in the late twenties. Onset before the age of 17 is known as early-onset, and before the age of 13, as can sometimes occur, is known as childhood schizophrenia or very early-onset. Onset can occur between the ages of 40 and 60, known as late-onset schizophrenia. Onset over the age of 60, which may be difficult to differentiate as schizophrenia, is known as very-late-onset schizophrenia-like psychosis. Late onset has shown that a higher rate of females are affected; they have less severe symptoms and need lower doses of antipsychotics. The tendency for earlier onset in males is later seen to be balanced by a post-menopausal increase in the development in females. Estrogen produced pre-menopause has a dampening effect on dopamine receptors but its protection can be overridden by a genetic overload. There has been a dramatic increase in the numbers of older adults with schizophrenia.Onset may happen suddenly or may occur after the slow and gradual development of a number of signs and symptoms, a period known as the prodromal stage. Up to 75% of those with schizophrenia go through a prodromal stage. The negative and cognitive symptoms in the prodrome stage can precede FEP by many months and up to five years. The period from FEP and treatment is known as the duration of untreated psychosis which is seen to be a factor in functional outcome. The prodromal stage is the high-risk stage for the development of psychosis. Since the progression to first episode psychosis is not inevitable, an alternative term is often preferred of at risk mental state. Cognitive dysfunction at an early age impacts a young person's usual cognitive development. Recognition and early intervention at the prodromal stage would minimize the associated disruption to educational and social development and has been the focus of many studies.