Time perception

What is time perception?

Time perception involves the capacity to accurately process temporal information that is embedded in relevant events. The ability to perceive, remember, and organise behaviour in periods ranging from seconds to minutes mediates functions, from basic motor coordination to decision making. As time intervals make different demands on other cognitive processes, it is difficult to disentangle deficits in temporal perception from deficits in attention and memory.

There are several types of time perception. Explicit timing involves a deliberate estimate of a discrete duration of time, while implicit timing is an automatic process that is engaged whenever sensorimotor information is temporally structured. Automatic timing involves no attentional or cognitive modulation and is primarily involved in timing intervals in the subsecond range. Cognitively controlled timing is primarily based on higher level cognitive processes such as attention and memory that are recruited for longer periods. Perceptual timing involves estimates of duration in the form of perceptual discrimination, while motor timing involves estimates of duration in the form of motor response.

What is the evidence for time perception?

Moderate quality evidence suggests a medium-sized effect of poorer explicit timing in people with schizophrenia than in controls, with no significant differences in the effect size according to type of timing task (automatic vs. controlled) or method of timing task (motor vs. perceptual).

 

June 2017

Treatments for cognitive symptoms

What are cognitive symptoms?

Cognitive symptoms of schizophrenia have been found in all cognitive domains, including executive function, memory, and attention, and often develop prior to the other symptoms of schizophrenia. They are highly disabling and predict poor functional outcomes.

What is the evidence for treatments for cognitive symptoms?

Moderate to high quality evidence suggests second generation antipsychotics in general are associated with small improvements in processing speed, verbal fluency, learning, motor skills, and global cognition when compared to first generation antipsychotics, but have no benefit over first generation antipsychotics for improving attention, cognitive flexibility, working memory, delayed recall, visuospatial processing. Moderate quality evidence suggests small benefits of second-generation antipsychotics over first-generation antipsychotics for improving long-term memory. There are small benefits of first-generation antipsychotics for improving general cognitive function relative to placebo.

Moderate to high quality evidence shows haloperidol is associated with small improvements in global cognition (low haloperidol dose only), verbal learning (low and high dose), delayed recall (low and high dose), and attention (low dose only), when compared to second generation antipsychotics, with no differences for executive function, verbal fluency, motor skills, or processing speed. Moderate to low quality evidence suggests sertindole may be superior to; clozapine, quetiapine, and first generation antipsychotics for general cognitive ability; clozapine, quetiapine, and olanzapine for memory; clozapine, quetiapine, olanzapine and ziprasidone for executive functioning; and quetiapine for processing speed. Olanzapine may superior to clozapine and first generation antipsychotics for visuospatial skills and verbal fluency. Moderate to high quality evidence suggests small benefits of antidepressants over placebo for global cognition and executive functioning.

Also see the Signs and Symptoms cognition and cognitive remediation topics.

September 2016

Metacognitive training

What is metacognitive training?

Research has found that many people with schizophrenia have biased cognitive processes, and have a lack of insight about these problems. Biased cognitive processes are thought to underlie delusional beliefs. The aim of metacognitive training is to make patients aware of delusion-relevant cognitive biases and then to amend these biases. Cognitive biases in people with schizophrenia involve a tendency to jump to conclusions based on a small amount of information, and make errors when trying to find reasons for their own and others’ behaviours. Research has shown that people with schizophrenia are often unsure about their correct interpretation of information, but are over-confident about their incorrect interpretation of information. Metacognitive training involves eight group sessions with three to ten patients, and is based on three fundamental components. First, knowledge translation involves describing cognitive biases in a way that explains how they contribute to the formation of delusions. Second is the use of specific exercises to raise awareness about the negative consequences of cognitive biases, and third, patients are taught alternative thinking strategies to help them avoid the cognitive biases that can lead to delusional beliefs. Patients are encouraged to express personal examples of biases, and discuss ways to counter them, serving to provide corrective experiences in a supportive atmosphere.

What is the evidence for metacognitive training?

High quality evidence suggests a small improvement in positive symptoms with metacognitive training, but no benefit for delusions.

 

June 2017

Metacognition

What is metacognition?

Metacognition refers to ‘thinking about thinking’ and involves active control over the cognitive processes engaged in thinking and acquiring knowledge or learning. Metacognition also involves the notion of self, ranging from self as own body to self as own identity or ‘agency’. A sense of body ownership occurs regardless of whether an action is generated by the self or others, whereas a sense of agency refers to the sense of being the one who initiates an action. Sense of agency is linked to the ability to maintain the distinction between the individual and the environment. Intrusive thoughts are generally defined as thoughts that are unwanted or unintended, and can be perceived as uncontrollable. It is argued that when intrusive thoughts are experienced, any inconsistency between metacognitive beliefs about one’s ability to control thoughts and the experience of uncontrollable intrusive thoughts may lead to cognitive dissonance, a state of negative arousal. From this perspective, hallucination prone individuals are motivated to attribute their intrusive thoughts to an external source in the attempt to prevent cognitive dissonance
from occurring.

What is the evidence for metacognition?

High quality evidence suggests impaired self-awareness, particularly sense of agency, and poor self-recognition in people with schizophrenia compared to controls. Moderate quality evidence suggests people experiencing hallucinations or hallucination proneness have increased thoughts of uncontrollability and danger, cognitive confidence, and cognitive self-consciousness compared to people not experiencing hallucinations or hallucination proneness.

 

April 2016

Cognition in high-risk groups

Who are people at high-risk of psychosis?

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?

High quality evidence shows a small to medium-sized effect of lower general intelligence, poor executive functioning, attention, visual memory, and social cognition in people at high risk of psychosis compared to people who are not at high risk of psychosis. Moderate to high quality evidence also suggests lower visual-spatial ability, olfactory functioning, verbal fluency, verbal memory, working memory, and learning. High quality evidence suggests 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 people at clinical high risk, and people at clinical high risk were more impaired on visuospatial working memory than people at familial high risk. Moderate quality evidence showed that people at high risk who converted to psychosis showed a medium-sized effect of lower olfactory functioning, general cognitive ability, language functioning, visual-spatial ability, memory, attention and executive functioning prior to conversion than people not at high risk of psychosis. Compared to people at high risk who did not convert to psychosis, moderate quality evidence showed that people at high risk who did converted to psychosis showed small to medium-sized effects of poor visual learning and working memory. Moderate to low quality evidence also suggests a medium-sized effect of lower general intelligence, verbal fluency, verbal memory, and visual memory.

 

April 2016

Cognitive remediation

What is cognitive remediation?

Cognitive remediation (with or without computers) uses repetitive exercises to improve cognitive deficits that are often experienced by people with schizophrenia. Cognitive deficits may include problems with attention, memory, reasoning, problem solving, and social functioning.

What is the evidence for cognitive remediation?

Moderate to high quality evidence suggests a medium-sized benefit of cognitive remediation for improving attention, memory, executive functioning, processing speed, social cognition and social functioning. There may also be a small benefit for improving the overall symptoms of schizophrenia. Moderate to low quality evidence suggests similar levels of effectiveness for both short and long durations of cognitive remediation training. Strategy learning that focuses on providing alternative strategies to compensate for the difficulties with cognition may be more generally effective than rehearsal learning. Environmental changes that reduce cognitive demands on people with schizophrenia may also improve symptoms and motivation levels.

Also see Signs and Symptoms cognition topics.

May 2016

Reasoning ability

What is reasoning ability?

Reasoning refers to the ability to logically gather information to form conclusions and solve problems. People with schizophrenia may show impaired reasoning, with bias in the way they gather information, interpret events and develop beliefs. Reasoning bias is measured in three ways: “jumping to conclusions” (JTC) is when a decision is made after little information is gathered; belief inflexibility is an inability to change a belief even when presented with contradictory evidence; and attribution bias is when available evidence is incorrectly used to attribute negative or positive events to internal or external causes.

What is the evidence for reasoning ability?

High quality evidence shows a small association between poor reasoning ability and severity of negative symptoms. Moderate quality evidence also suggests an association with severity of disorganised symptoms and, to a lesser extent, severity of reality distortion symptoms. High quality evidence shows a medium-sized association between better social problem solving and social skills and better reasoning ability. Greater community functioning and better social behaviour show a weaker association with better reasoning ability. Moderate quality evidence suggests medium to strong associations between poor reasoning ability and problem solving, and poor verbal learning, processing speed, working memory, attention and vigilance, and verbal fluency. There are weaker associations with poor emotion perception, social perception, facial recognition and emotion processing.

Moderate to high quality evidence suggests no difference in reasoning and problem solving ability in people with schizophrenia taking second generation antipsychotics compared to those taking first generation antipsychotics. Moderate quality evidence suggests better problem solving and reasoning ability is found in people with schizophrenia with a cannabis use disorder compared to people with schizophrenia without any substance use disorder.

 

April 2016

Decision making

What is ‘decision making’ referring to? 

Decision making requires an individual to use their knowledge and experience of a context in order to choose a course of action. A person’s 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. People with schizophrenia may show altered decision-making processes and impairments in their capacity to provide informed consent to medical or psychiatric treatment. People with impaired decisional capacity may not be able to understand information relating to the decision; appreciate the significance of the information and apply the information to decision-making; reason and compare potential consequences of the decision in a logical process; and/or communicate this decision. Decision making and decisional capacity may be associated with other areas of cognitive functioning, with a certain level of mental functioning required to make the most appropriate decisions in the situation.

What is the evidence for decision making?

Moderate to low quality evidence suggests people with schizophrenia are more likely to make decisions with disadvantageous consequences than people without schizophrenia. This effect is greater in people receiving second generation antipsychotics, and in people with catatonic, psychotic, or negative symptoms. Impaired understanding and appreciation of information regarding consent to treatment and research is associated with more severe psychopathology, particularly negative symptoms.

 

April 2016

Memory

What is memory? 

Memory involves encoding, storage and retrieval of information. Short-term memory is the ability to remember information after several seconds or minutes; and long-term memory is the ability to remember information over a longer duration. Working memory involves information being temporarily held as well as manipulated. Episodic memory is long-term memory for autobiographical events. Semantic memory is memory for general facts, prospective memory is memory for future actions, and retrospective memory is memory for past events. Most memory tasks assess retrospective memory by measuring recall and recognition.

What is the evidence for memory?

Compared to controls, high quality evidence suggests a medium to large effect of poor working memory and prospective memory in people with schizophrenia. Moderate to high quality evidence also suggests a large effect of poor short-term memory, memory binding, and long-term memory. High quality evidence shows a small effect of better nonverbal episodic memory in males with schizophrenia compared to females with schizophrenia. Compared to people with affective psychoses (e.g. bipolar disorder), high quality evidence shows a medium-sized effect of poor visual delayed, verbal immediate, and verbal delayed memory in people with schizophrenia. Moderate quality evidence also suggests poor verbal working memory, but not spatial working memory. High quality evidence suggests people at clinical high risk of psychosis are more impaired on visuospatial working memory than people with a family history of psychosis. Moderate quality evidence suggests a small effect of poor working memory in people at clinical high risk for psychosis who transition to psychosis compared to people at clinical high risk for psychosis who do not transition to psychosis.

High quality evidence shows small to medium-sized associations between increased negative or disorganised symptoms and poor visual and verbal memory, with moderate quality evidence also suggesting a weak association with poor executive working memory. High quality evidence shows small to medium-sized associations between poor prospective memory and more severe general psychopathology, increased medication dose, duration of the illness, age, and decreased education and premorbid IQ. A medium-sized association is reported between better memory and higher levels of insight.

Moderate quality evidence suggests people taking olanzapine or risperidone show improvements in working memory after treatment, while people taking clozapine or quetiapine show no improvements in working memory. People taking olanzapine, clozapine or risperidone show improvements on delayed recall after treatment, while people taking quetiapine show no improvements. High quality evidence suggests improvements on delayed recall tasks with haloperidol.

 

 

April 2016

Learning

What is learning? 

Learning is the ability to acquire, or change, existing knowledge, behaviours or skills. There are two distinct forms of learning: explicit (or declarative) learning occurs during a high level of consciousness regarding specific learnt content, for example, memorising information for an exam. Implicit (or procedural) learning is less conscious and refers to learning which is gained from task performance, for example, juggling. Explicit verbal learning can be measured with the Hopkins Verbal Learning test, the California Verbal Learning test and verbal list-learning. The Brief Visuospatial memory test, the Rey design learning test, the Rey complex figure test, and visual reproduction all measure explicit visual learning. Implicit learning can be measured using the Serial Reaction Time task where learning is inferred from reduced reaction time to stimuli.

What is the evidence for learning?

Compared to people without schizophrenia, moderate to high quality evidence suggests a medium to large effect of poor performance in people with schizophrenia in verbal learning cued and free recall, verbal memory span, verbal paired associate learning, verbal recognition, and Serial Reaction Time. Compared to people with affective psychosis (e.g. bipolar disorder), high quality evidence shows a small effect of poor performance in people with schizophrenia on the California Verbal Learning Test total free recall subscale, but not on the long delayed free recall or recognition hits subscales.

High quality evidence suggests a small to medium-sized association between more severe negative or disorganised symptoms and poor visual and verbal learning. In general, moderate to high quality evidence suggests greater improvements in explicit learning but not implicit learning in people with schizophrenia taking second generation antipsychotics compared to people taking first generation antipsychotics. Specifically, people taking second generation olanzapine, clozapine or risperidone, or first generation haloperidol, show improvements, but patients receiving second generation quetiapine show no improvements in learning.

High quality evidence shows better community functioning, social behaviour and problem solving ability are associated with better verbal learning, while lower work capacity is associated with poor verbal learning. There is a small effect of better verbal learning and memory in people with a psychotic disorder and a substance use disorder than in people with a psychotic disorder and no substance use disorder.Moderate quality evidence suggests small to medium-sized effects of poorer visual learning in people at clinical high risk for psychosis who transitioned to psychosis compared to people at clinical high risk for psychosis who did not transition to psychosis, with no differences in verbal learning.

 

April 2016