Procedural learning of cognitive and motor skills in psychotic patients

Sleep-dependent memory consolidation in schizophrenia: A systematic review and meta-analysis

Sleep disturbances and cognitive impairment are both persistent and common features of schizophrenia. Accumulating evidence indicates that sleep-dependent memory consolidation might be impaired in patients with schizophrenia compared to healthy controls. The current systematic review was performed in accordance with PRISMA guidelines. A random-effects model was used to calculate effect sizes (Hedge's g). In the quantitative review, three separate meta-analyses were conducted for procedural memory in healthy controls, schizophrenia, and comparison between healthy controls and schizophrenia. Additionally, separate meta-analyses were conducted for the studies using finger tapping motor sequence task, as it is the most commonly used task. The current systematic review included 14 studies including 304 patients with schizophrenia and 209 healthy controls. The random-effects model analyses for sleep-dependent procedural memory consolidation resulted in a small effect size in schizophrenia (g = 0.26), a large effect size in healthy controls (g = 0.98), a moderate effect size in healthy controls vs schizophrenia (g = 0.64). For the studies using finger tapping motor sequence task, meta-analyses resulted in a small effect size in schizophrenia (g = 0.19), a large effect size in healthy controls (g = 1.07), a moderate effect size in healthy controls vs schizophrenia (g = 0.70). In the qualitative review, there was also impaired sleep-dependent declarative memory consolidation in schizophrenia compared to healthy controls. Current findings support that sleep improves memory consolidation in healthy adults, but there is a deficit in sleep-dependent memory consolidation in people with schizophrenia. Future studies investigating sleep-dependent consolidation of different memory subtypes with polysomnography in different stages of psychotic disorders are needed.

Self-concept, emotion and memory performance in schizophrenia

The "self-reference effect" describes better memory for material someone has related to one's self previously. Schizophrenia can affect aspects of the inner self such as own thoughts or actions. Schizophrenia symptoms, therefore, might not only have an influence on the self-concept, including the self-attribution of positive or negative personality traits, but also reduce the self-reference effect. 15 schizophrenia patients and 15 matched healthy controls were asked to decide on positive and negative personality traits across three separate conditions: self-evaluation, other evaluation (of an intimate person), and during a lexical control task, respectively. An unannounced recognition task followed. Patients revealed a negative bias in the evaluation of themselves and of the well-known other person. The reference to a person (oneself, close other) increased later recognition performance. However, patients with schizophrenia revealed an overall decreased recognition performance. The amount of patients' passivity symptoms, i.e., an increase in the permeability of their "self-other boundary", correlated negatively with their recognition performance for previously self-referred characteristics and traits referred to the intimate other. This was not the case for lexically processed stimuli or an increase of negative symptoms. Our data underline the necessity of taking into account symptom subgroups when dealing with specific cognitive dysfunctions in schizophrenia.

Memory for everyday actions in schizophrenia

In healthy people, enacting actions by manipulating objects improves memory compared to verbal encoding of the description of the same actions. We used this paradigm to test memory for actions in 40 stable schizophrenia participants and 24 healthy volunteers. Three encoding conditions were used and consisted of action sentences that were: 1) self-performed by the participants, 2) performed by an experimenter (observed), or 3) encoded verbally. Memory for those actions was tested in two formats. First a cued-recall task with the object as a retrieval cue was administered. Secondly source recognition was examined by asking the participants to decide in which of the three conditions each action was encoded. On cued-recall, schizophrenia participants largely benefited from self-enacting actions, reaching performance levels comparable to that of the healthy volunteers. On the source recognition test however, they showed a substantial impairment. The present study thus indicates that people with schizophrenia can benefit from the enactment effect. However, the fact that their performance was reduced considerably during source recognition relative to healthy volunteers suggests that the beneficial effect provided by enactment was mostly implicit.

Deficit in schizophrenia to recruit the striatum in implicit learning: a functional magnetic resonance imaging investigation

In schizophrenia, explicit learning deficits have been well established although it is less clear whether these patients have deficits in implicit learning (IL). IL is thought to depend on intact striatal functioning. This study examined the hypothesis that schizophrenia patients show deficient recruitment of striatal activation during an IL paradigm, relative to performance-matched healthy comparison subjects. Ten subjects with schizophrenia on atypical antipsychotic medication and 10 age, gender, education, and performance matched healthy comparison subjects underwent fMRI while performing an IL task. On the basis of whole-brain and striatal region-of-interest analyses, we found a relative lack of striatal activation in schizophrenia patients. This result is consistent with convergent evidence of striatal dysfunction in schizophrenia.

State-dependent implicit learning deficit in schizophrenia: evidence from 20-month follow-up

Previous research has confirmed stable explicit memory deficits in schizophrenia across disease states. However, little is known about the implicit learning capabilities of individuals with schizophrenia across the course of illness. The current study assessed procedural learning in 19 schizophrenia subjects (DSM-IV criteria) and 19 matched controls using the Serial Reaction-Time Task (SRTT). The severity of negative, positive and disorganized symptoms was assessed using the Scales for the Assessment of Positive and Negative Symptoms. A sub-sample of 11 schizophrenia subjects and 11 controls was reassessed 20 months later when symptoms in the schizophrenia subjects had largely remitted. Schizophrenia subjects were severely impaired on sequence-specific procedural learning during an acute episode. This deficit could not be explained by a general memory or processing speed impairment. Impaired implicit learning scores were significantly related to higher ratings of disorganized symptoms. However, 20 months later, when acute symptoms had remitted, the performance of the schizophrenia subjects on procedural learning had normalized. Our findings might share a conceptual overlap with previous reports of a reduced ability of schizophrenia subjects during an acute episode to adapt ongoing perceptual and behavioral programs to previously experienced regularities in their environment.

Prism adaptation in schizophrenia

The prism adaptation test examines procedural learning (PL) in which performance facilitation occurs with practice on tasks without the need for conscious awareness. Dynamic interactions between frontostriatal cortices, basal ganglia, and the cerebellum have been shown to play key roles in PL. Disruptions within these neural networks have also been implicated in schizophrenia, and such disruptions may manifest as impairment in prism adaptation test performance in schizophrenia patients. This study examined prism adaptation in a sample of patients diagnosed with schizophrenia (N=91) and healthy normal controls (N=58). Quantitative indices of performance during prism adaptation conditions with and without visual feedback were studied. Schizophrenia patients were significantly more impaired in adapting to prism distortion and demonstrated poorer quality of PL. Patients did not differ from healthy controls on aftereffects when the prisms were removed, but they had significantly greater difficulties in reorientation. Deficits in prism adaptation among schizophrenia patients may be due to abnormalities in motor programming arising from the disruptions within the neural networks that subserve PL.

The dual origin hypothesis: An evolutionary brain-behavior framework for analyzing psychiatric disorders

According to the dual origin hypothesis, the cerebral cortex of higher mammals evolved from two primordial brain structures, the amygdala and hippocampal formation. This developmental process defines the orderly principles of cortical connectivity and gives rise to functionally distinct ventral and dorsal systems within the cerebrum. This paper reviews the basic features of the dual origin theory. This model is then applied to understanding symptom production in a number of psychiatric illnesses, with particular reference to recent structural and functional imaging studies. In this paper I propose that psychiatric symptoms can be conceptualized as arising from abnormal processing within dorsal (time-space-motility) or ventral (meaning-motivation) systems, or from a disturbance in the functional interaction/balance between them. Within this framework, one can identify symptom-specific correlations that cross-traditional diagnostic boundaries, as well as potential mechanisms that may explain biologically valid diagnostic entities. Integrating evolutionary, connectional and functional bases across multiple species, the dual origin hypothesis offers a powerful neural systems model to help organize our understanding of psychiatric illness, therein suggesting novel approaches to diagnosis, prevention and treatment.

The effect of Ondansetron on memory in schizophrenic patients

It has been well established that patients with schizophrenia have impaired cognitive function on neuropsychological tasks related to memory. Previous studies also suggest serotonin's central role in memory. This double-blind crossover study aimed to explore the effect of Ondansetron, a selective serotonin 3 receptor (5-HT(3)) antagonist, on a variety of memory tasks in schizophrenic patients. Clozapine-treated schizophrenic patients in remission (N=21) were randomly treated with Ondansetron or placebo and then evaluated at three consecutive points. These evaluations included clinical measures (including Positive and Negative Syndrome Scale for Schizophrenia, Clinical Global Impression and Extrapyramidal Symptoms Rating Scale) and neuropsychological measures (including Digit Span, Paired Association, Rey-Osterich Complex Figure Test, Digit Symbol and the Rivermead Behavioral Memory Tests). Ondansetron, when compared with placebo, did not affect the above clinical measures and most of the neuropsychological tests. Short-term administration of Ondansetron, however, was associated with significantly improved visuo-spatial memory as measured by the Rey-Osterich Complex Figure Test. These preliminary results suggest Ondansetron's possible role in enhancement of memory function in schizophrenia.

A Meta-Analysis of Cognitive Deficits in Adults with a Diagnosis of Schizophrenia

This review identified 1275 studies examining cognitive deficits in people with schizophrenia, published between 1990 and 2003. Data from 113 studies (4365 patients and 3429 controls) were combined in a meta-analysis carried out on the five cognitive domains of IQ, memory, language, executive function, and attention. Studies were excluded where they lacked a suitable control group or failed to present complete information. In all five cognitive domains, analysis indicated a consistent trend for patients to perform more poorly than healthy controls, with significant heterogeneity across studies. Sources of heterogeneity were analyzed and a need to ensure more appropriate composition of patient and control groups and to adopt a more refined and methodologically correct, hypothesis-driven approach was identified.

Stability of set-shifting and planning abilities in patients with schizophrenia

Patients with schizophrenia have deficits in executive function that involve attentional set-shifting and planning ability. It is unclear, however, whether such deficits are stable during the course of the illness or if they fluctuate in response to medication effects or symptom changes. Patients with a DSM-IV diagnosis of schizophrenia (n=28) and healthy control subjects (n=17) were tested on computerised measures of attentional set-shifting and planning at baseline and 9-month follow-up. The measures used were the Intra/Extradimensional Shift test (ID/ED) and the Stockings of Cambridge test (SoC) from the Cambridge Automated Neuropsychological Testing Battery (CANTAB). On both tests, the patients were poorer than controls at baseline; however, there was no evidence of change over the 9-month follow-up. Additionally, there was little evidence of a relationship between executive test performance and medication or length of illness. This study accords with the presence of executive processing deficits in schizophrenia that are stable across time.

Procedural learning in schizophrenia after 6 months of double-blind treatment with olanzapine, risperidone, and haloperidol

RATIONALE

First generation antipsychotics induce extrapyramidal motor symptoms (EPS), presumably through dopamine D(2) receptor blockade at the dorsal striatum. This may also produce impairment of cognitive processes, such as procedural learning, that are dependent on this region. Haloperidol and, to a lesser extent, risperidone, are active in the dorsal striatum and may induce EPS and impairment of procedural learning. In contrast, the prototypical second-generation antipsychotic, clozapine, is less active in the dorsal striatum and does not induce EPS or impair procedural learning. Olanzapine is pharmacologically similar to clozapine and has a low incidence of EPS induction.

OBJECTIVES

To assess the hypothesis that olanzapine would not have a deleterious effect on procedural learning.

METHODS

Thirty-nine subjects with early phase schizophrenia were randomly assigned to double blind treatment with haloperidol, risperidone, or olanzapine. They were administered the Tower of Toronto test at an unmedicated baseline and again following 6 weeks and 6 months of treatment.

RESULTS

Procedural learning, defined as the improvement observed between two blocks of five trials of the Tower of Toronto, was preserved after 6 weeks of all three treatments but showed a substantial decline after 6 months of treatment with haloperidol or risperidone.

CONCLUSIONS

These data are consistent with the differential activity of the three medications in dorsal striatum structures and suggest that the advantages of olanzapine over haloperidol and risperidone in relation to extrapyramidal syndromes may also generalize to procedural learning. The results also suggest that the procedural learning disadvantages of haloperidol and risperidone accrue slowly but are apparent after 6 months of treatment.

Effect of L-tryptophan on memory in patients with schizophrenia

ABSTRACT It has been well established that patients with schizophrenia have impaired cognitive abilities on neuropsychological tasks related to memory. Previous studies also suggest a central role for serotonin in memory. This double-blind crossover study aimed to explore the effect of l-tryptophan, a serotonin precursor, on a variety of memory tasks in schizophrenic patients. Antipsychotic-treated schizophrenic patients in remission (N = 21) were randomly treated with l-tryptophan or placebo and then evaluated at three consecutive points on clinical measures (including Positive and Negative Syndrome Scale for Schizophrenia, Clinical Global Impression, and Extrapyramidal Symptoms Rating Scale) and by neuropsychological tests (including Digit-Span, Paired Association, Rey-Osterich Complex Figure Test, Digit Symbol, Number Facility Test, and the Rivermead Behavioral Memory Tests. Compared with placebo, l-tryptophan had a beneficial effect on memory functions but not on the patients' psychotic state or on the side effects of medications. These preliminary results suggest the possibility of using serotonin precursor to enhance memory function in schizophrenia.

Basal ganglia N-acetylaspartate correlates with the performance in the procedural task 'Tower of Hanoi' of neuroleptic-naive schizophrenic patients

We tested the hypothesis that basal ganglia dysfunction may be related to procedural learning impairment in schizophrenia. We determined the N-acetylaspartate/choline (NAA/Cho) ratio in the left striatal area in 11 young first-episode antipsychotic-naive patients and matched controls. Procedural learning was assessed by the four-disk version of the Tower of Hanoi. Analysis of variance showed that the number of moves and the execution time had a significant group effect (P=0.02, P<0.0001, respectively). Correlation analysis between procedural learning and the NAA/Cho ratio showed a negative significant correlation only in patients, measured by both time (P=0.006) and by moves (P=0.001). In summary, we found that schizophrenic patients have impaired procedural learning, and that this impairment is related to basal ganglia metabolism.

Verbal declarative memory dysfunction in schizophrenia: from clinical assessment to genetics and brain mechanisms

The recent literature on the neuropsychology of schizophrenia has emphasized memory deficits as a key area of impairment. Abnormalities in the medial temporal lobe, a brain region crucial for long-term memory formation, have also consistently been reported. We conducted a comprehensive review of verbal declarative memory (VDM) in schizophrenia with the aim of systematically addressing the nature of this impairment. We conclude that verbal declarative memory is significantly impaired in schizophrenia and is largely accounted for by deficits in the encoding stage. Subtle impairments in increased rates of forgetting are present, but are mild compared with those in amnestic disorders. Impairment in other cognitive domains studied thus far (e.g., attention), medication effects, or fluctuations in symptoms do not completely account for the deficit. VDM is among the most impaired neurocognitive domains in schizophrenia (along with attention and executive functions). Milder encoding deficits are present in high-risk subjects and non-psychotic relatives of individuals with schizophrenia suggesting that components of the deficit are associated with a genetic vulnerability to the illness, and are independent of the frank psychotic illness. Furthermore, VDM is observed in individuals experiencing their first-psychotic episode and it remains fairly consistent over time. Preliminary imaging studies and other work suggest abnormalities in prefrontal-hippocampal processing networks. Future work should emphasize delineating specific information processing components contributing to the deficit. This would allow imaging studies to determine which brain regions contribute to specific information processing deficits in schizophrenia.

Cognitive function in schizophrenia. Deficits, functional consequences, and future treatment

This article has discussed the relationship between cognitive deficits and functional outcome in schizophrenia. This relationship was noted first by Kraepelin and Bleuler at the beginning of the twentieth century. With the introduction of conventional neuroleptics, the focus shifted toward the treatment of positive symptoms. In the past few decades, cognitive dysfunction has been recognized as a fundamental feature of schizophrenia and has been shown repeatedly to have a negative association with functional outcome [6]. Improvement in cognitive functioning became one of the most important clinical targets in the treatment of schizophrenia in the 1990s [82]. Main domains of cognition that are disrupted significantly in schizophrenia include attention, executive function, verbal and visuospatial working memory, and learning and memory. Although conventional antipsychotics are effective in treating positive symptoms, they lack the ability to improve cognitive impairment and produce poor functional outcome. Previous research has shown superior efficacy of atypical antipsychotics on cognitive impairments in schizophrenia compared with conventional antipsychotics. Because the heterogeneity of atypical antipsychotics in their pharmacologic properties, they have differential profiles of cognitive efficacy in patients with schizophrenia. Establishing the cognitive profile of each atypical antipsychotic is an important task. This knowledge can be used to address individual cognitive problems and needs. Because cognitive deficits have been shown to have associations with different aspects of clinical symptoms, limited learning in rehabilitation programs, and functional outcome in schizophrenia, targeting individual cognitive deficits would lead to greater treatment success in terms of clinical and functional outcome. Although atypical antipsychotics have some benefit on cognitive function, further efforts to improve cognitive function are required. Attempts at improving cognition in schizophrenia with specific cognitive enhancers pharmacologically and psychological therapies such as cognitive remediation might lead to better functional outcome in patients with schizophrenia.

Procedural memory in schizophrenia assessed using a mirror reading task

The preservation of procedural memory in individuals with schizophrenia has been confirmed by methods such as the Tower of Hanoi, pursuit rotor and mirror reading tests. However, the cognitive procedural memory of Japanese subjects with schizophrenia has never been assessed using mirror reading. To better determine the characteristics of cognitive procedural memory in schizophrenia, a Japanese version of the mirror reading task, consisting of cards with words written in Japanese katakana characters in mirror image, was administered to 18 Japanese patients with schizophrenia and 21 normal controls. The results indicated that the patients indeed learned the skill despite exhibiting lower overall performances in reading time than the controls, their scores displaying correlation with the severity of schizophrenic negative symptoms. This suggests that procedural memory for this task is retained in individuals with schizophrenia. It is important for them to use their preserved procedural memory for efficient rehabilitative efforts.

Individual differences in latent neuropsychological abilities at addictions treatment entry

The latent structure of neuropsychological abilities and risk factors for impairment were examined in 197 persons entering addictions treatment. Confirmatory factor analysis yielded 4 factors: Executive, Memory, Verbal, and Processing Speed. The measurement model was consistent with evidence that neuropsychological test performance is factorially complex and supported by multiple brain regions. Path analyses showed that risk factors explained 34%-57% of the true variance in abilities. Age, education, and medical status had the most generalized and robust associations with abilities. Drug use disorder diagnoses, childhood behavior problems, familial alcoholism, and psychopathology were also significantly related to specific latent abilities. Knowledge of neuropsychological impairment may be clinically useful, and selected risk factors may help treatment providers decide which clients should receive formal neuropsychological assessment.

Cognitive functioning, cortisol release, and symptom severity in patients with schizophrenia

BACKGROUND

There is substantial evidence of dysregulation of cortisol secretion, hippocampal abnormalities, and memory deficits in schizophrenia and other psychotic disorders. Research also suggests that cortisol secretion augments dopaminergic activity, which may result in increased symptom expression in this clinical population.

METHODS

We examined the relations among cortisol release, cognitive performance, and psychotic symptomatology. Subjects were 18 adults with schizophrenia or schizoaffective disorder, seven with a nonpsychotic psychiatric disorder, and 15 normal control subjects. Tests of memory and executive function were administered. Cortisol was assayed from multiple saliva samples.

RESULTS

Findings indicated the following: 1) patients with psychotic disorders scored below the comparison groups on the cognitive measures; 2) for the entire sample, cortisol levels were inversely correlated with performance on memory and frontal tasks; and 3) among patients, cortisol levels were positively correlated with ratings of positive, disorganized, and overall symptom severity, but not with negative symptoms.

CONCLUSIONS

The present results suggest that abnormalities in the hypothalamic-pituitary-adrenal axis and hippocampal systems play a role in observed cognitive deficits across populations. Among psychotic patients, elevated cortisol secretion is linked with greater symptom severity.

Practice-related improvement in information processing with novel antipsychotic treatment

BACKGROUND

Attentional deficits are prominent in schizophrenia, and skill learning is impaired. Novel antipsychotic treatment has been reported to improve certain cognitive skills in schizophrenic patients, but no information is yet available about the effect of newer medications on skill learning.

METHODS

Clinically stable patients with schizophrenia (n=16) and chronically hospitalized inpatients (n=8) were recruited while receiving conventional antipsychotic treatment. Subjects were tested at baseline on a visual continuous performance test (CPT), performed alone and simultaneously with an auditory CPT. Normal controls (n=8) were also tested at baseline. The inpatients and half of the outpatients were switched to treatment with risperidone. All patients then performed the visual CPT on a daily basis and performed the dual tasks once per week, for 4weeks.

RESULTS

Patients who remained on conventional medications did not improve in their performance despite the extensive practice on the test. Both chronic and stable patients receiving risperidone treatment manifested a statistically significant (P<0.05) improvement from baseline on both single and dual-task visual CPT. Stable outpatients performed significantly better at the end of the protocol than the normal controls performance at baseline (P<0.05).

IMPLICATIONS

These results suggest that practice-related improvements in the performance of information processing tests are enhanced by novel antipsychotic medications. Although the specific biological mechanism of this effect is not yet known, the results may suggest that use of newer medications will enhance skill development and perhaps facilitate rehabilitation of patients with schizophrenia.

Does long-term memory deficit relate to patients' slowness in schizophrenia?

INTRODUCTION

The performance of fast and slow schizophrenic patients and matched controls was examined in a delayed free recall task to assess whether the patient's slowness would influence long-term memory (LTM) in a similar way to working memory.

METHOD

Twenty-three schizophrenic patients who met DSM-IV criteria and were matched in age and educational level to 23 controls participated. Subjects' reading rate was measured, and a cut-off of mean controls' reading rate minus 2 standard deviations was allowed the identification of 9 slow patients. The memory task comprised a list of 20 unrelated common words presented visually that were to be recalled in any order after a delay of 25-30 minutes filled with unrelated tasks.

RESULTS

The overall patients' performance was poor compared with controls, and slow and fast performance was comparable, contrasting with immediate memory tasks in which slow patients were impaired compared with fast patients.

CONCLUSION

Patients' slowness does not seem to influence the long-term memory deficit in schizophrenia.

Cognitive deficits and cognitive training in schizophrenic patients: a review

OBJECTIVE

The aim of this paper is to review the current status of knowledge of cognitive deficits and remediation in patients with schizophrenia.

METHOD

Relevant reports were identified by a literature survey. In addition, some outstanding researchers in these areas were asked to add to the identified list relevant literature that was not included.

RESULTS

Our review focuses on the cognitive deficits observed in the areas of attention, memory and executive functions. We attempt to classify dysfunctions as vulnerability- or symptom-linked factors, and we discuss the methodological question of a general performance deficit vs. a differential deficit. Furthermore, we briefly delineate how antipsychotics affect cognitive functions. Finally, controlled studies of cognitive training are discussed in more detail.

CONCLUSION

The most outstanding cognitive dysfunctions in patients with schizophrenia can be related to the areas of attention, memory and executive functions. Interest in cognitive remediation has to some extent been rekindled in the 1990s. However, few studies on the effects of cognitive training programs have been conducted.

Tower of Hanoi and WCST performance in schizophrenia: problem-solving capacity and clinical correlates

We administered a computerized version of WCST, a well established test, sensitive to executive function deficits in schizophrenia that involves many features of cognitive processing, and of Tower of Hanoi, a test that may offer cognitive challenges more specifically related to planning and sequencing, to 28 schizophrenic patients and 28 matched controls to examine a worthwhile question regarding the relative ability of these two tasks to differentiate schizophrenia and normal groups as well as exploring the relationship of these two instruments to clinical variables. The schizophrenic patients performed significantly worse than normal subjects both on Tower of Hanoi test and on WCST. The discriminant analysis identified in a multivariate way a pattern of indexes that differentiate the two groups. This pattern, characterized by specific indexes of WCST and TOH, could suggest the existence of a common underlying factor that determines the cognitive impairment in problem-solving of schizophrenics. These findings and the relationship with positive and negative symptoms have been discussed in the light of the model of the impairment in the internal representation of context information.

The construct validity of the Tower of LondonDX as a measure of the executive functioning of ADHD children

Currently, there are a limited number of measures that have been developed to assess childhood executive planning and problem-solving abilities. The present study represents ongoing efforts to determine the psychometric properties of the newly developed Tower of London Drexel (TOLDX), a measure of executive functions. Specifically, the construct-related validity of the TOLDX was investigated with a sample of attention-deficit hyperactivity disorder (ADHD) children (N = 129), 7 to 15 years of age. The performance of the children on a neuropsychological battery of measures sensitive to executive abilities, psychometric intelligence, and memory was subjected to maximum-likelihood factor analysis. A four-factor solution was extracted that best fit the selected variables. The TOLDX was found to produce the highest loading on an Executive Planning/Inhibition factor comprised of other executive measures. The Executive Planning/Inhibition measure was separate from factors of Executive Concept Formation/Flexibility, Psychometric Intelligence, and Memory. Moreover, the two executive factors were found to be correlated (r = .42) suggesting that each assesses, to varying degrees, related executive dimensions. The neuropsychological construct structure of the TOLDX is discussed in relationship with the temporal organization of behavior and frontal lobe functioning.

Preservation of cognitive procedural memory in a case of Korsakoff's syndrome: methodological and theoretical insights

Using the Tower of Hanoï puzzle, Butters, et al. in 1985 illustrated the difficulties in learning the procedure and questioned the suitability of this task for assessment of the cognitive procedural memory in Korsakoff's syndrome. Our objective, in the light of these criticisms, was to show preservation of cognitive procedure capacities with the Tower of Hanoï for a man (P.F.) who was suffering from alcoholic Korsakoff's syndrome. For this procedural task, some aids helped to compensate in part for the difficulties with declarative memory and with working memory. In this condition, P.F. was able to learn the cognitive procedure. This study suggests that cognitive procedure memory may be preserved in some patients suffering from Korsakoff's syndrome and that this may be shown when a suitable task is used. The result makes it possible to discuss the interaction between declarative and procedural knowledge in the solving of the Tower of Hanoï.

Adaptation of visually guided behavior during reversed vision in schizophrenia: a preliminary study

This preliminary study evaluated the adaptation of visually guided behavior to reversed vision in schizophrenia. The study included 54 patients who met DSM-III-R criteria for schizophrenia. Visuomotor reaction times (VRTs) during reversed vision were measured in six blocks of 35 consecutive trials. The VRTs of schizophrenics were compared with those of normal subjects. A good fit (R2 = 0.9981) for the adaptation process of VRTs during reversed vision was found with the equation y = 1030 + 1499/x, where x is the order of the block and y is the group mean VRT for each block. The VRTs in schizophrenics were significantly slower than those in normal subjects. However, the adaptation process to reversed vision essentially did not differ from normal. The adaptation of visually guided behavior during reversed vision may involve procedural learning; this task may thus be useful in evaluating such learning. The VRTs during reversed vision may be related to some aspects of symptoms in the patient with schizophrenia and may also be useful in predicting clinical outcome.

Effects of acute administration of d-amphetamine and haloperidol on procedural learning in man

The effects of an indirect dopamine-agonist, d-amphetamine, and a non-selective dopamine receptor antagonist, haloperidol, were investigated in normal male volunteers using a between-subjects double-blind design in a procedural learning task, thought mainly to involve unconscious/automatic learning. The results showed: (1) d-amphetamine facilitated response speed, whereas haloperidol inhibited it, in comparison to placebo; (2) the linear increase in procedural learning corresponded with pharmacological manipulation of degree of dopaminergic activity, i.e. subjects given haloperidol showed the least, and subjects given d-amphetamine the greatest, procedural learning. The implications of these findings are discussed in relation to investigation of abnormalities of procedural learning processes in schizophrenia.

PET brain mapping study of auditory verbal supraspan memory versus visual fixation in schizophrenia

Changes in regional cerebral blood flow (rCBF), associated with performance of an auditory verbal supraspan memory task, were studied in eight remitted DSM-III-R schizophrenic patients and eight pair-wise matched normal controls. Four positron emission tomography (PET) scans, using the [15O]-H2O technique, were acquired: two while subjects fixated a cross hair and two while performing a verbal free-recall supraspan memory task. Task performance showed typical patterns of recency and primacy effects in both groups; however, patients performed more poorly than controls on the primary (working) memory aspect of the task. Regions showing rCBF changes overlapped in both groups and were similar to those seen in previous studies of normals; however, patients had smaller increases in rCBF than controls in frontal and superior temporal cortical regions bilaterally. Our results suggest that remitted patients with schizophrenia demonstrate impairments of capacity-limited information processing, which may be related to metabolic dysfunction within a distributed network of brain structures, including the prefrontal and temporal cortical regions; however, dysfunction limited to the frontal cortex cannot be ruled out by the results of this experiment.

Memory impairment in schizophrenia: perspectives from psychopathology and pharmacotherapy

OBJECTIVE

To describe the concept of memory impairment in schizophrenia and the clinical implications of this concept in terms of patient assessment and neuroleptic drug use.

METHOD

Narrative literature review.

RESULTS

Individuals suffering from schizophrenia normally exhibit some degree of memory impairment. Recent work in psychopathology indicates that the impairment is comprehensive, involving the sensory, short-term, and long-term memory stores. Memory impairment appears to be a primary symptom of the disease, and its underlying causes are likely organic. A number of medications, however (for example, traditional neuroleptics and drugs that have pronounced anticholinergic activity), may cause or exacerbate impairment. In particular, anticholinergic agents used to treat extrapyramidal symptoms, a common complication of neuroleptic drugs, appear to have a deleterious effect on memory.

CONCLUSIONS

Memory impairment is an important consideration in the clinical assessment and management of patients with schizophrenia. The use of atypical antipsychotics like risperidone appears to have no impact on memory function; because risperidone is associated with a low incidence of extrapyramidal side effects, it can obviate the need for anticholinergic medications-thus offering greater hope of nondebilitative intervention. The advent of medications that are safer (on cognition) could also lead to generally better outcomes by facilitating compliance with drug regimens and rehabilitation programs.

The heterogeneity of memory dysfunction in schizophrenia

OBJECTIVE

To characterize the memory dysfunction of schizophrenic patients.

METHOD

The components of the human memory system are described, and then a review of the various memory deficits identified among patients suffering from schizophrenia is presented. Finally, an overview of the latest developments in the comprehension of schizophrenia and a discussion on certain proposals advanced by various researchers in the field intended to shed light on the disorder is provided.

RESULTS

Schizophrenia appears to be an amalgamation of many different disorders. No single model for identifying the disorder has been able to encompass every aspect of schizophrenia.

CONCLUSION

Future studies will need to consider new ways of selecting and grouping schizophrenic patients.

Memory deficits in subsyndromes of chronic schizophrenia

Recent psychopathological studies consistently identified a delusional, a negative, and a disorganized subsyndrome in chronic schizophrenia. The aim of the present study was to investigate these subsyndromes with respect to declarative, procedural and working memory deficits. While the delusional subsyndrome was associated with an impaired delayed recognition, the negative subsyndrome showed a marked deficit in delayed recall. In addition, the delusional and the negative subsyndrome shared procedural memory changes. The disorganized subsyndrome was associated with neurological soft signs and a poor working memory performance. These results do not seem to be effected by severity of illness, degree of chronicity, nor attentional deficits. Our findings support the differentiation of three subsyndromes in chronic schizophrenia and suggest that memory impairment in schizophrenia may reflect the involvement of different memory systems rather than an unspecific, global deficit.

Are the frontal lobes implicated in "planning" functions? Interpreting data from the Tower of Hanoi

Twenty adult patients with lesions in the prefrontal cortex were tested on the Tower of Hanoi puzzle. The performance of patients was significantly worse than that of controls. This difference could not be accounted for in terms of a general decline in intelligence or memory, or by the size of the lesion. The results further suggest that both patients and controls used the same general strategy to solve the problem and that patients' difficulties with the task have little to do with planning or "look ahead" deficits (as is generally assumed in the neuropsychology literature). Patient performance is best explained in terms of an inability to see or resolve a goal-subgoal conflict. This interpretation is compatible with several existing accounts of frontal lobe dysfunction that postulate a failure of inhibition of a prepotent response to explain poor performance on the Wisconsin Card Sorting task, the Stroop task, the Antisaccade task, the A-Not-B task, and the Delayed Alternation task.