Early detection refers to the correct identification of individuals who are at high risk of developing schizophrenia, with an emphasis on the development of frank psychosis. Generally, there are two approaches that dictate the characteristics used as markers for detection. The first is the ultra-high risk approach which focuses on a triad of at-risk mental states defined as having a family history of psychosis plus non-specific symptoms and recent decline in functioning, recent onset of attenuated psychotic symptoms with decline in functioning, and brief, intermittent and limited psychotic symptoms. The other approach is based on Huber’s Basic Symptoms, which focuses on a detailed way of describing subjective disturbances, and may be an earlier indicator of risk.

What is the evidence for early detection of psychosis?

Moderate to high quality evidence found the mean rate of transition to psychosis in those assessed as being at clinical high risk is around 16% by 2 years and 29% by 3 years. In adolescents and young adults (16-24 years) who were diagnosed with attenuated psychotic syndrome, transition rates were 11% by 6 months, 15% by 12 months, 20% by 2 years months, and 23% by 3 years. In children (<18 years) assessed as being at clinical high risk, transition rates were between 17% and 20% by 1 year follow-up and between 7% and 21% by 2 year follow-up. 36% of children and adolescents recovered from their clinical high risk status by 6-year follow-up, and 40% continued to meet clinical high risk criteria without transition to psychosis.

People assessed as being at clinical high risk of obsessive-compulsive disorder were at higher risk of psychosis transition than people assessed as being at clinical high risk of bipolar disorder, which in turn had higher risk of psychosis than people assessed as being at high risk of depression. The rate of transition to psychosis was one third the rate of transition to non-psychotic disorders in people at assessed as being at clinical high risk for any non-psychotic disorder.

Studies with older samples reported higher transition rates than studies with younger samples, and more recent publications reported lower transition rates than older publications. Studies using the basic symptoms approach reported higher transition rates than studies using the ultra-high risk approach. Studies of people receiving psychosocial treatments for high risk groups (e.g., cognitive behavioural therapy) reported lower transition rates than studies of people receiving standard care (e.g., case management). Studies of people on antipsychotics also reported lower transition rates than studies of people not on antipsychotics.

Moderate to high quality evidence suggests instruments based on ultra-high risk criteria have good sensitivity and moderate specificity. Moderate to low quality evidence found the Assessment of Basic Symptoms Scale has good sensitivity and moderate specificity. This indicates validated tools are generally good at correctly identifying individuals who do develop psychosis, but not as good at identifying individuals who do not develop psychosis.

Moderate quality evidence suggests the model with the best predictive value (86%) for transition to psychosis was a clinical model including odd beliefs, marked impairment in role functioning, blunted affect, auditory hallucinations, and anhedonia/asociality. A biological model using grey matter volume, and a neurocognitive model using IQ, verbal memory, executive functioning, attention, processing speed, and speech perception, both had positive predictive values of ~83%. An environmental model with a positive predictive value of 63% involved urbanicity, social-sexual aspects, and social-personal adjustment. The best combination model had a positive predictive value of 82% and involved disorganised communication, suspiciousness, verbal memory deficit, and decline in social functioning.

February 2022

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Standardised assessment tools are vital for assessing a range of variables including symptoms, functioning and quality of life. The quality of these tools can be measured in various ways. ‘Reliability’ refers to the reproducibility of an instrument’s results across different assessors, settings and times. ‘Construct validity’ is the extent to which an instrument measures the theoretical construct it was designed to measure. This involves ‘convergent validity’ (the degree of correlation between different scales measuring the same construct); and ‘divergent validity’ (the lack of correlation between scales measuring different constructs). ‘Known groups’ validity’ is the extent to which an instrument can demonstrate different scores for groups known to vary on the variables being measured. ‘Content validity’ is the extent to which each item on a scale represents the construct being measured, and ‘internal consistency’ is the degree of correlation between items within a scale. ‘Predictive validity’ refers to sensitivity, which is the proportion of correctly identified positives (e.g. high ratings on a scale), and specificity, which is the proportion of correctly identified negatives (e.g. low ratings on a scale). ‘Responsiveness’ is the extent to which an instrument can detect clinically significant or practically important changes over time.

What is the evidence for outcome assessment tools for schizophrenia?

Moderate quality evidence suggests the Brief Psychiatric Rating Scale can be factored into five discrete components, comprising positive, negative, and affective symptoms, resistance (hostility) and activation (excitement). The Positive and Negative Syndrome Scale showed a similar factor structure but included a larger number of items in the negative symptom factor and enough items for a discrete disorganisation factor. There is increased detection of symptoms when assessments are conducted in the mother language rather than an acquired language.

Moderate to high quality evidence found good predictive value of the Brief Psychiatric Rating Scale and the Positive and Negative Syndrome Scale for predicting non-response to antipsychotic treatment at 4-12 weeks. There is good predictive validity of the Historical, Clinical and Risk Management-20 scale for predicting aggression in psychiatric facilities. Moderate to low quality evidence suggests the McNiel-Binder Violence Screening Checklist, and the Brøset Violence Checklist may also be effective for predicting aggression or violence, however, the Violence Risk Appraisal Guide had poor predictive validity in people with schizophrenia living in the community.

Moderate quality evidence suggests good inter-rater reliability and some predictive validity for tools assessing duration of untreated psychosis, psychosis onset and treatment onset. Moderate to low quality evidence suggests the Recovery Assessment Scale has the best psychometric properties for measuring personal recovery; it has good construct validity, content validity, internal consistency, test-retest reliability, administrator-friendliness, and has been translated to languages other than English. However, its user-friendly rating is poor. Other scales rating personal recovery with reasonable psychometric properties include the Self-Identified Stage of Recovery scale, which has good construct and content validity, good internal consistency but poor test-retest reliability, and good user-friendliness, and has also been translated to languages other than English. The Mental Health Recovery Measure has good content validity but poor construct validity, and good internal consistency and test-re-test validity. Moderate quality evidence suggests good ‘known groups’ validity for the Short Form health survey-36, but inconsistent convergent validity and poor responsiveness.

Moderate to low quality evidence finds reliability is good for the following instruments assessing depressive symptoms; Brief Psychiatric Rating Scale-Depression, Positive and Negative Syndrome scale-Depression, Hamilton Rating Scale for Depression, Montgomery Asberg Depression Rating Scale, Calgary Depression Scale for Schizophrenia, and Beck Depression Inventory. The best concurrent validity indices are reported for the Calgary Depression Scale for Schizophrenia, and the Montgomery Asberg Depression Rating Scale. The highest ranges for sensitivity and specificity were reported for the Calgary Depression Scale for Schizophrenia. For anxiety symptoms, the Beck Anxiety Index, Depression Anxiety Stress Scale or Scale of Anxiety Evaluation in Schizophrenia for general screening, and the DSM-based Generalised Anxiety Disorder Symptoms Severity Scale, Liebowitz Social Anxiety Scale, Obsessive-Compulsive Inventory, Psychological Stress Index, Perseverative Thinking Questionnaire, and Yale-Brown Obsessive Compulsive Scale for anxiety symptoms.

February 2022

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Schizoaffective disorder is on the schizophrenia spectrum of illnesses. Diagnosis of schizoaffective disorder requires schizophrenia-like symptoms of psychosis, in addition to affective/mood symptoms such as depression. There is some debate as to whether schizoaffective disorder represents a unique diagnosis or an intermediary between schizophrenia and mood disorders. There are also considerable differences between different diagnostic criteria regarding the definition of schizoaffective disorder; particularly the Diagnostic and Statistical Manual (DSM) and the International Classification of Diseases (ICD) criteria. Specifically, the ICD and also the Research Diagnostic Criteria (RDC) require simultaneous and equally prominent presence of psychotic and affective symptoms; conversely, the DSM requires an additional period (>2 weeks) where the psychotic symptoms alone are present.

What is the evidence relating to schizoaffective disorder diagnosis?

Moderate to low quality evidence suggests schizoaffective disorder occupies an intermediary position between schizophrenia and mood disorders, but is not clearly distinct from either disorder.

Moderate quality evidence found people diagnosed with schizoaffective disorder using RDC/ICD criteria may have had fewer hospitalisations, are more likely to be male, and are more likely to be older or married than people diagnosed using DSM IIIR/IV criteria. Compared to people with schizophrenia, people with schizoaffective disorder may be more likely to be male, Caucasian, married, have a longer duration of illness, have lower levels of functioning, more depression, and more negative symptoms. Compared to people with bipolar disorder, people with schizoaffective disorder may be younger, have an earlier age at onset, fewer years of education, not Caucasian or African American, never married, have a longer duration of illness, more positive and negative symptoms, more depression, and higher IQ.

Around 36% of people initially diagnosed with schizoaffective disorder have their diagnosis changed at the second assessment. Conversely, around 55% of people diagnosed with schizoaffective disorder at the second assessment were originally diagnosed with other disorders. Schizophrenia or affective disorders were the most common original or subsequent diagnosis.

February 2022

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Diagnostic scales are widely used within clinical practice and research settings. These scales have been extensively validated and provide a set of criteria that is used to define and diagnose an illness. Two key examples include the American Psychiatric Association’s Diagnostic and Statistical Manual (DSM) and the World Health Organization’s International Classification of Diseases (ICD). Both the DSM and ICD criteria are regularly updated, and the most recent versions are the DSM-5 and the ICD-11.

For a DSM-5 diagnosis of schizophrenia, at least two symptoms need to have been present for at least six months, and for a significant portion of time over a one-month period. Symptoms include delusions, hallucinations, disorganised speech and behaviour, and negative symptoms such as diminished emotional expression, poverty of speech, and lack of purposeful action. At least one symptom of delusions, hallucinations, or disorganised speech needs to be present, and there also needs to be significant social or occupational dysfunction.

For an ICD-11 diagnosis of schizophrenia, at least two symptoms must be present, including positive, negative, depressive, manic, psychomotor, and cognitive symptoms. Of the two symptoms, one core symptom needs to be present, such as delusions, thought insertion, thought withdrawal, hallucinations, or thought disorder. Symptoms should have been present for most of the time during a period of at least one month.

What is the evidence on schizophrenia diagnosis?

Moderate to high quality evidence finds the DSM-III, DSM-III-R, and DSM-IV diagnostic criteria assigns more males with psychosis to schizophrenia than any other psychosis. Males are also found to have more negative symptoms. The ICD-9 shows no differences in gender distribution.

Moderate quality evidence finds Black people in the United States are more likely to be diagnosed with schizophrenia than White people in the United States. This is regardless of diagnostic method (structured vs. unstructured), or DSM version (DSM-III or DSM-IV). This effect was largest in studies with more males, more White patients, more young patients, studies in hospital or military settings, and studies conducted in the Midwest, Southeast, National, or multistate USA.

Moderate to high quality evidence suggests the proportion of first-episode psychosis patients retaining a diagnosis of schizophrenia over time is around 90%, and 72% for schizoaffective disorder. Also, the rate of a schizophrenia diagnosis following a diagnosis of schizophreniform disorder is around 65% over four years. Following brief, atypical, or not otherwise specified psychoses, the rate of a schizophrenia diagnosis is around 36% over four years. Following a substance-induced psychosis, the rate of a schizophrenia diagnosis is around 25% over four years. The rates of a transition to schizophrenia were highest for cannabis-induced psychosis, hallucinogen-induced psychosis, and amphetamine-induced psychosis.

Moderate to high quality evidence suggests better reliability for a diagnosis of schizophrenia than for a diagnosis of schizoaffective disorder. There was evidence to support vector machines combined with other machine learning techniques applied to structural and functional neuroimaging data (particularly prefrontal and temporal) for assisting the clinical diagnosis of schizophrenia.

February 2022

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Schizophreniform disorder is a part of the schizophrenia spectrum of disorders and has sometimes been used as a provisional diagnosis while waiting to see if symptoms improve by six months or progress, resulting in a diagnosis of schizophrenia. DSM-5 requires at least one of the following symptoms is present for a significant portion of the time during a one-month period, but for less than six months: delusions, hallucinations or disorganised speech. Disorganised behaviour or negative symptoms may also be present. There can be no manic, depressive or mixed manic-depressive episodes, and any mood disturbance must have been present for  minority of the time. The symptoms cannot be due to the effects of a substance or due to a medical or neurological disorder.

What is the evidence for schizophreniform disorder?

Moderate to high quality evidence suggests the rate of a schizophrenia diagnosis following a diagnosis of schizophreniform disorder is around 65% by about four years. The rate of first-episode psychosis patients retaining a diagnosis of schizophreniform disorder over time is around 29%.

February 2022

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