Selective attention is the ability to focus on relevant stimuli and ignore irrelevant stimuli. Sustained attention is the ability to maintain a consistent focus. Several tasks have been developed to assess attention performance. Examples include the Continuous Performance Test (CPT), which uses both visual and auditory stimuli and requires participants to respond to targets and ignore distractors. Other examples include the Trail Making Test (TMT), which requires participants to connect, in order, letters and/or numbers as quickly as possible, and the Wisconsin Card Sorting Test (WCST) that tests the ability to display flexibility during changing schedules. The Stroop Colour Word Test (SCWT) presents the name of a colour printed in an ink congruent to the colour name (e.g. blue), or incongruent to the colour name (e.g. blue), and participants are asked to either read the word or name the ink colour. Attention tasks may also measure other cognitive constructs, such as processing speed and memory.

What is the evidence for attention?

Moderate to high quality evidence shows medium to large effects of poorer performance on various attention and vigilance tasks in people with schizophrenia compared to people without schizophrenia. There are small to medium-sized associations between poorer attention and more severe symptoms, poorer community functioning, and poorer social skills. People taking olanzapine or quetiapine showed medium to large improvements on attention tasks after treatment. People taking haloperidol showed small improvements after treatment, and people taking clozapine or risperidone showed no improvement after treatment.

High quality evidence found people at clinical high risk of psychosis and people at familial high risk for psychosis are similarly impaired on attention tasks. Moderate to high quality evidence shows a medium-sized effect of better attention in people at clinical high-risk than people with first-episode psychosis. Those at risk who converted to psychosis were more impaired on attention tasks than those at risk who did not convert to psychosis.

Compared to people with bipolar disorder, moderate to high quality evidence shows people with schizophrenia have slightly poorer performance on attention tasks. There was also poorer performance on attention tasks in people with schizophrenia who were herpes simplex virus positive or had metabolic syndrome than in people with schizophrenia who were herpes simplex virus negative or did not have metabolic syndrome. There was a small effect of greater impairment in attention in smokers vs. non-smokers with schizophrenia, however people with schizophrenia and a substance use disorder performed better on attention tasks than people with schizophrenia and no substance use disorder.

March 2022

Image: ©nelos – stock.adobe.com

The post Attention appeared first on NeuRA Library.

There are two key approaches for identifying people with early signs that may suggest a high risk of developing psychosis or schizophrenia. The first approach is based on Huber’s Basic Symptoms, which focuses on a detailed way of describing phenomenological (subjective) disturbances. Because the basic symptoms refer only to subtle subjectively experienced abnormalities, they may reflect an earlier phase in the disease process than the second approach, which identifies at-risk mental states as a combination of; a family history of psychosis (familial risk) plus non-specific symptoms and recent decline in functioning; recent onset Attenuated Psychotic Symptoms with decline in functioning; and Brief Limited Intermittent Psychotic Symptoms.

What is the evidence for cognitive functioning in high-risk groups?

Moderate to high quality evidence found medium-sized effects of poorer verbal learning, reasoning and problem-solving, visual memory, verbal memory, working memory, olfaction, visual learning, and executive functioning in people at clinical high-risk for psychosis compared to controls. There were also small effects of poorer general intelligence, processing speed, attention/vigilance, premorbid intelligence, visuospatial ability, social cognition, and motor functioning in people at clinical high risk for psychosis.

High quality evidence shows people at clinical high risk of psychosis and familial high risk of psychosis are similarly impaired on processing speed, verbal and visual memory, attention and language fluency when compared with controls. People at familial high risk were more impaired on premorbid and current IQ than those at clinical high risk, and those at clinical high risk were more impaired on visuospatial working memory than those at familial high risk.

Moderate quality evidence found medium-sized effects of poorer verbal learning, visual memory, and executive functioning in people at high-risk of psychosis who made the transition to psychosis compared to people at high-risk of psychosis who did not make the transition to psychosis. There were small effects of poorer processing speed, attention/vigilance, and general intelligence in those who transitioned to psychosis, with no differences in working memory, premorbid intelligence, olfaction, or motor functioning.

Moderate quality evidence finds medium-sized effects of better verbal learning, general intelligence, and executive functioning in people at high-risk of psychosis compared to people with first-episode psychosis. There were no differences in premorbid intelligence or processing speed.

High quality evidence finds small improvements in cognition over time in people at ultra-high risk of psychosis and in people with first-episode psychosis.

March 2022

Image: ©ninefotostudio – stock.adobe.com

The post Cognition in high-risk groups appeared first on NeuRA Library.

Cognitive deficits are core features of both schizophrenia and bipolar disorder. Establishing differences in cognition between these disorders may be useful for identifying differences in the underlying illness pathologies, and may provide potential targets for individual treatments.

What is the evidence for cognitive functioning in schizophrenia and bipolar disorder?

Moderate to high quality evidence shows small to medium-sized effects of poorer global cognition, executive functioning, social cognition, processing speed, attention, reasoning and problem solving, learning, and memory in people with schizophrenia (including early onset schizophrenia) compared to bipolar disorder (including paediatric bipolar disorder).

There was a medium-sized effect of poorer pre-illness onset cognitive functioning and a large effect of poorer post-illness onset cognitive functioning in people with schizophrenia compared to controls without a mental illness. In people with bipolar disorder compared to controls without a mental illness, there was a small effect of poorer pre-illness onset cognitive functioning and a medium-sized effect of poorer post-illness onset cognitive functioning. People with schizoaffective disorder showed poorer cognitive performance than people with bipolar disorder, but better cognitive performance than people with schizophrenia.

March 2022

Image: ©iconicbestiary – adobe.stock.com

The post Cognition in schizophrenia and bipolar disorder appeared first on NeuRA Library.

Schizophrenia is characterised by positive, negative and disorganised symptoms. Positive symptoms refer to experiences additional to what would be considered normal experience, such as hallucinations and delusions. Negative symptoms include blunted affect, impoverished thinking, alogia, asociality, avolition, and anhedonia. Alogia is often manifested as poverty of speech, asociality involves reduced social interaction, avolition refers to poor hygiene and reduced motivation, while anhedonia is defined as an inability to experience pleasure. Disorganised symptoms involve bizarre behaviour and disorganised thought and speech. Cognitive deficits are also a core feature of schizophrenia. These deficits may be present in chronic patients, as well as prior to onset of the disorder and during its early and acute stages. Cognitive deficits may be associated with specific symptoms as well as functional impairment.

What is the evidence for cognitive functioning relating to symptom dimensions?

Moderate to high quality evidence shows more severe overall symptoms are associated with poor prospective memory, insight, executive functioning, facial perception, facial emotion recognition, emotion processing and perception, social perception, and Theory of Mind.

More severe positive symptoms are associated with poorer insight, attention/vigilance, reasoning, problem solving, non-emotional recognition, self-recognition, psychomotor speed, executive functioning, Theory of Mind, verbal list learning and digit span performance. More severe negative symptoms are associated with poorer language fluency, IQ, attention, memory, learning, speed of processing, reasoning, executive functioning, insight, social cognition, and olfaction. More severe disorganised symptoms are associated with poorer IQ, attention, executive functioning, speed of processing, reasoning/problem solving, and memory, but not verbal working memory. Thought disorder was associated with poorer semantic priming and verbal fluency.

March 2022

Image: ©carlosgardel – stock.adobe.com

The post Cognitive functioning related to symptoms appeared first on NeuRA Library.

Decision making requires the use of knowledge and experience of a context in order to choose a course of action. The ability to autonomously make decisions is referred to as their decisional capacity. Effective decision-making aims to increase the likelihood of a favourable outcome in the relevant context, selecting responses that avoid unfavourable or harmful outcomes.

An experimental tool used to examine decision-making is the Iowa Gambling Task. On each trial, participants choose a card from one of four decks and receive a monetary gain or loss. Two decks (A, B) are disadvantageous and two decks (C, D) are advantageous. The decks also differ according to the amount of immediate gain, the relative frequency of gains vs. losses and the relative number of net losses. The goal is to maximize monetary outcome through adaptive decision-making across many trials.

Another experimental tool is the MacArthur Competence Assessment Tool, which assesses the ability to understand the relevant information, the ability to reason rationally, the ability to appreciate a situation and its consequences, and the ability to communicate a choice.

What is the evidence for decision making?

High quality evidence found medium to large impairments in understanding, appreciation and reasoning decision-making and a small impairment in expression of a choice decision making. Effect sizes were smaller in studies using enhanced informed consent for people with schizophrenia.

Moderate to high quality evidence found poorer performance on the Iowa Gambling Task, with more A and B deck choices and fewer D deck choices. There were also fewer C deck choices, although this was not significantly different to controls.

Moderate quality evidence found more severe psychotic symptoms and poorer verbal cognitive functioning are associated with reduced decision-making ability about treatment (small to medium-sized effects).

March 2022

Image: ©mantinov – stock.adobe.com

The post Decision making appeared first on NeuRA Library.

Defeatist performance beliefs are over-generalised negative thoughts about one’s ability to successfully perform goal-directed behaviour. This prevents the initiation of and engagement in social and employment opportunities and therefore is considered a possible contributing factor to negative symptoms and poor functional outcomes.

Neurocognitive deficits in memory and attention for example may contribute to unsuccessful goal attainment, which over time can give rise to dysfunctional attitudes, including defeatist performance beliefs. These dysfunctional attitudes, in turn, may lead to a decrease in motivation for future goal-related activities, which may contribute to functional outcome deficits. Reduction in goal-directed behaviour reinforces further disengagement with the social world.

What is the evidence for defeatist performance beliefs?

High quality evidence suggests significant but small relationships between increased defeatist performance beliefs and worse negative symptoms and functional outcomes (e.g. general functioning, quality of life, life skills).

March 2022

Image: ©terovesalainen – stock.adobe.com

The post Defeatist performance beliefs appeared first on NeuRA Library.

Episodic future thinking refers to thought processes that contribute to the mental construction, imagination or simulation of possible future events. Episodic future thinking plays a role in planning, problem-solving, coping, regulating emotional states and goal-motivated behaviour.

What is the evidence for episodic future thinking?

Moderate to low quality evidence suggests a large effect of poorer detail and specificity of episodic future thinking in people with schizophrenia compared to controls.

March 2022

Image: ©Preechar Bowonkitwanchai – stock.adobe.com

The post Episodic future thinking appeared first on NeuRA Library.

Executive functions are a group of cognitive processes involving control, mental flexibility, planning, inhibition, decision-making, initiation, abstraction, self-monitoring and pursuit of goals. Any impairment in executive functioning can also reflect impairments in other cognitive functions such as processing speed, attention, and memory. Executive functioning is most commonly measured using the Wisconsin Card Sorting Task (WCST). This task requires the ability to shift cognitive sets. Other common tasks include the Trail Making Test (TMT), which requires participants to connect, in order, letters and/or numbers as quickly as possible, and the Stroop Colour Word Test (SCWT), which presents colour names printed in an ink congruent to the colour name (e.g. blue), or incongruent to the colour name (e.g. blue); participants are asked to either read the word or name the ink colour. Verbal fluency tests involve participants naming as many words as possible from a particular category in a given time, and Go/No-Go tasks involve presenting participants stimuli in a continuous stream and asking them to make a ‘go’ or a ‘no-go’ response to each stimulus.

What is the evidence for executive functioning in schizophrenia?

Compared to people without schizophrenia, moderate to high quality evidence found people with schizophrenia show medium-sized impairments on the WCST, verbal fluency tasks, inhibition tasks, planning tasks, the TMT, the SCWT, and the Go/No-Go task. Compared to people with affective psychoses (including bipolar disorder) there were small impairments on verbal fluency tasks, the TMT, and the WCST. There were small to medium-sized impairments on the WCST in first-degree relatives of people with schizophrenia and in people at clinical high-risk of psychosis compared to people without schizophrenia. There was poorer executive functioning in individuals at clinical high-risk of psychosis who made the transition to psychosis compared to individuals at clinical high-risk of psychosis who did not make the transition to psychosis. There were similar, small improvements on executive functioning tasks over time (1 to 5 years) in people at clinical high-risk of psychosis and in people with first-episode psychosis.

Moderate to high quality evidence shows a medium-sized association between higher levels of executive functioning and higher levels of insight and lower levels of negative or disorganised symptoms (including formal thought disorder). Moderate quality evidence found no association between executive functioning and positive symptoms.

There were greater improvements in verbal fluency in people receiving second-generation antipsychotics compared to people receiving first-generation antipsychotics. People receiving quetiapine, olanzapine, or clozapine may show improvements on verbal fluency tasks post-treatment, however people receiving risperidone may show no improvement on these tasks.

March 2022

Image: ©Gajus – stock.adobe.com

The post Executive functioning appeared first on NeuRA Library.

Information processing involves a number of cognitive functions, including perception, attention, memory and decision making, as well as the speed at which these cognitive functions are executed. Any impairment in information processing can reflect impairments in these other cognitive domains. Information processing can be assessed using various tests. The Wechsler Adult Intelligence Scale (WAIS) digit symbol coding test presents participants with paired numbers and symbols and when shown several numbers, participants must write down the missing corresponding symbols as quickly as possible. The Wisconsin Card Sorting Task (WCST) requires an ability to shift cognitive sets; participants are asked to match stimulus cards, with feedback provided as to whether the match was correct or incorrect based on a colour, quantity, or design rule that changes during the task. The Trail Making Test (TMT) requires participants to connect, in order, letters and/or numbers as quickly as possible. The Stroop Colour Word Test (SCWT), presents colour names printed in an ink congruent to the colour name (e.g. blue), or incongruent to the colour name (e.g. blue). Participants are asked to either read the word or name the ink colour. Category fluency is an oral test that requires participants to name as many items in a category (e.g. furniture items) as they can in one minute.

What is the evidence for information processing?

Compared to people without schizophrenia, high quality evidence shows a large effect of poorer information processing in people with first-episode or chronic schizophrenia. Moderate to high quality evidence found no differences in initial thinking time, but more subsequent thinking time on the SOC task.

Moderate to high quality evidence also found a large effect of slower processing speed in people at high risk who converted to psychosis compared to controls, and a small effect in non-converters compared to controls. There was slower processing speed in people with first-episode psychosis than in people at clinical high-risk of psychosis.

Compared to people with affective psychoses (including bipolar disorder and schizoaffective disorder), moderate to high quality evidence found small effects of poorer information processing on the TMT and WCST tasks.

Moderate to high quality evidence found a medium-sized association between better information processing and better community functioning, and weak associations between better information processing and better emotion processing and less severe symptoms. High quality evidence found a small impairment in speed of processing in smokers vs. non-smokers with schizophrenia. Moderate to high quality evidence suggests better speed of processing in people with schizophrenia with any substance use disorder compared with people with schizophrenia without any substance use disorder.

There were greater improvements in processing speed in people taking second-generation antipsychotics than in people taking first-generation antipsychotics. People taking olanzapine, clozapine or risperidone showed improvements in processing speed after treatment, while people taking quetiapine or haloperidol showed no improvement.

March 2022

Image: ©freshidea – Fotolia – adobe.stock.com

The post Information processing appeared first on NeuRA Library.

Insight with regards to schizophrenia is defined as the awareness of having the disorder, including an understanding of the social consequences associated with the disorder; the need for treatment; effects of medication; awareness of the implications; and awareness of the signs and symptoms of the disorder. Clinical insight involves the awareness of the disorder and symptoms, while cognitive insight relates to the ability to question and consider one’s beliefs and judgements.

What is the evidence for insight?

Moderate quality evidence found more severe symptoms are related to lower levels of insight into the disorder and its consequences. Conversely, increased depression symptoms were related to increased levels of insight, and there was a small association between better insight and poorer quality of life.

Moderate to high quality evidence found small associations between better insight and higher IQ and better memory functioning. Moderate quality evidence found small associations between better insight and less aggression, better work and social functioning, increased treatment adherence, and fewer re-hospitalisations.

High quality evidence found a medium-size effect of more self-certainty in people at risk of psychosis compared to controls. Moderate quality evidence found no differences in self-reflectiveness or overall cognitive insight.

Moderate quality evidence found any treatment improves insight, particularly in combination with other treatments that target insight specifically.

February 2022

Image: ©Photomorphic Pte. Ltd – stock.adobe.com

The post Insight appeared first on NeuRA Library.