Specific executive/attentional deficits in patients with schizophrenia or bipolar disorder who have a positive family history of psychosis

Executive Functions in Students With Depression, Anxiety, and Stress Symptoms

Introduction:

This study aimed to investigate and compare the executive functions of students with depression, anxiety, and stress symptoms with those functions in healthy ones.

Methods:

This study was a comparative and non-clinical analysis. The study population comprised all students of Shahid Beheshti University, Tehran, Iran. A total of 448 students were recruited using convenience sampling method. They were also screened using the Depression Anxiety Stress Scales (DASS) test comprising 21 items. Of study participants, 30 people were depressed, 27 had anxiety, and 15 suffered from stress. Then, 50 control people were matched with them. Next, both groups were compared using the Stroop test, Wisconsin card sorting, and cognitive ability test.

Results:

Using MANOVA test, data analysis revealed no significant differences among 4 groups with regard to selective attention and shifting attention. Depressed group reacted rapidly as opposed to the anxiety group with regard to measures of shifting attention and cognitive abilities; it was observed that the memory, inhibition control, planning, and flexibility of the healthy group were better than those of the 3 other groups.

Conclusion:

The findings of this research raised specific issues in relation to the role of depression, anxiety, and stress in the disruption of the executive functions of sufferers. Selective and shifting attention and cognitive abilities are specifically affected in this regard. Meanwhile, the role of stress in impairing decision making and the major role of anxiety in impairing sustained attention was shown to be considerable.

A meta-analysis of temperament and character dimensions in patients with mood disorders: Comparison to healthy controls and unaffected siblings

BACKGROUND

Cloninger's psychobiological model of personality has been extensively applied to subjects affected by mood disorders (MOOD). However, most studies are widely heterogeneous in terms of sample size, methods of assessment, and selection of participants.

METHODS

We conducted a systematic review of literature and a random effects meta-analysis of studies comparing at least two of the following groups: (a) adults with a primary MOOD diagnosis (Bipolar Disorder (BP) or major depressive disorder (MDD)), (b) their unaffected siblings (SIB) or (c) healthy subjects (HS), and reporting quantitative results from the Tridimensional Personality Questionnaire (TPQ) or the Temperament and Character Inventory (TCI). Subgroup, sensitivity and meta-regression analyses were also conducted.

RESULTS

High Harm Avoidance and low Self-Directedness were consistently associated with MOOD and SIB samples. BP was characterized by higher scores in Novelty Seeking and Self-Transcendence than HS, SIB and MDD. Age seemed to have a negative effect on Novelty Seeking and a positive effect on Harm Avoidance, Cooperativeness and Self-Transcendence. An euthymic mood state was associated with reduced Harm Avoidance, but increased Reward Dependence, Self-Directedness and Cooperativeness.

LIMITATIONS

The quality of the included studies varied and was relatively low. Moreover, publication bias and heterogeneity in the distribution of effect sizes may also have limited our results.

CONCLUSION

High Harm Avoidance and Low Self-Directedness may be trait markers for MOOD in general, while high Novelty Seeking and high Self-Transcendence may be specific to BP. Future studies are needed to disentangle the state-trait effect of each personality dimension.

Developmental trajectory of cognitive impairment in bipolar disorder: comparison with schizophrenia

Both schizophrenia and bipolar disorder (BP) are associated with neurocognitive deficits. However, it has been suggested that schizophrenia, but not BP, is characterised by premorbid cognitive impairments and neurodevelopmental abnormalities. In this paper, studies investigating neurocognitive deficits in premorbid, high-risk and first-episode BP were reviewed and these findings were compared with outcome of studies in schizophrenia. Available evidence suggests that cognitive deficits are evident in first-episode BP and such deficits can be evident even years before the onset of the illness in some patients. Trajectory of cognitive deficits from childhood to adulthood can be very similar in schizophrenia and many patients with BP. Developmental lag in acquisition of cognitive skills is a risk factor for both disorders. However, unlike schizophrenia, not only impaired cognition but also supranormal premorbid cognitive/scholastic performance predict BP. Neurodevelopmental cognitive impairment is evident in some but not all patients with BP. A model suggesting that only BP patients who share common genetic risk factors with schizophrenia have premorbid neurodevelopmental cognitive deficits is proposed. In this model, combination of absence of neurodevelopmental abnormalities and BP-related temperamental characteristics explains the relationship between supranormal cognition and risk for BP.

The neurocognitive functioning in bipolar disorder: a systematic review of data

BACKGROUND

During the last decades, there have been many different opinions concerning the neurocognitive function in Bipolar disorder (BD). The aim of the current study was to perform a systematic review of the literature and to synthesize the data in a comprehensive picture of the neurocognitive dysfunction in BD.

METHODS

Papers were located with searches in PubMed/MEDLINE, through June 1st 2015. The review followed a modified version of the recommendations of the Preferred Items for Reporting of Systematic Reviews and Meta-Analyses statement.

RESULTS

The initial search returned 110,403 papers. After the deletion of duplicates, 11,771 papers remained for further evaluation. Eventually, 250 were included in the analysis.

CONCLUSION

The current review supports the presence of a neurocognitive deficit in BD, in almost all neurocognitive domains. This deficit is qualitative similar to that observed in schizophrenia but it is less severe. There are no differences between BD subtypes. Its origin is unclear. It seems it is an enduring component and represents a core primary characteristic of the illness, rather than being secondary to the mood state or medication. This core deficit is confounded (either increased or attenuated) by the disease phase, specific personal characteristics of the patients (age, gender, education, etc.), current symptomatology and its treatment (especially psychotic features) and long-term course and long-term exposure to medication, psychiatric and somatic comorbidity and alcohol and/or substance abuse.

Impairments of working memory in schizophrenia and bipolar disorder: the effect of history of psychotic symptoms and different aspects of cognitive task demands

Comparisons of cognitive impairments between schizophrenia (SZ) and bipolar disorder (BPD) have produced mixed results. We applied different working memory (WM) measures (Digit Span Forward and Backward, Short-delay and Long-delay CPT-AX, N-back) to patients with SZ (n = 23), psychotic BPD (n = 19) and non-psychotic BPD (n = 24), as well as to healthy controls (HC) (n = 18) in order to compare the level of WM impairments across the groups. With respect to the less demanding WM measures (Digit Span Forward and Backward, Short-delay CPT-AX), there were no between group differences in cognitive performance; however, with respect to the more demanding WM measures (Long-delay CPT-AX, N-back), we observed that the groups with psychosis (SZ, psychotic BPD) did not differ from one another, but performed poorer than the group without a history of psychosis (non-psychotic BPD). A history of psychotic symptoms may influence cognitive performance with respect to WM delay and load effects as measured by Long-delay CPT-AX and N-back tests, respectively. We observed a positive correlation of WM performance with antipsychotic treatment and a negative correlation with depressive symptoms in BPD and with negative symptoms in SZ subgroup. Our study suggests that WM dysfunctions are more closely related to a history of psychosis than to the diagnostic categories of SZ and BPD described by psychiatric classification systems.

Generalized and specific neurocognitive deficits in psychotic disorders: utility for evaluating pharmacological treatment effects and as intermediate phenotypes for gene discovery

A growing body of research suggests that schizophrenia and bipolar disorder share overlapping clinical, neurobiological, and genetic features, raising important questions about the boundaries and distinctiveness of these 2 major psychiatric disorders. A generalized cognitive impairment has long been understood to be a core feature of schizophrenia. More recently, it has become apparent that cognitive impairment also occurs in bipolar disorder, particularly in those patients with a history of psychotic symptoms. Whether a generalized deficit exists across a spectrum of psychotic disorders is less clearly established. Additionally, in the context of a broad impairment, it remains a significant challenge to identify deficits in specific cognitive processes that may have distinct neurochemical or regional brain substrates and linkages to particular risk-associated genetic factors. In this article, we review the findings from neuropsychological studies across a spectrum that includes schizophrenia, schizoaffective and bipolar disorders, and conclude the available evidence strongly supports that a generalized deficit is present across psychotic disorders that differs in severity more so than form. We then consider the implications of generalized and specific deficits in psychosis for 2 areas of research--the evaluation of pharmacological treatments targeting cognitive deficits, and the investigation of cognitive intermediate phenotypes in family genetic studies. Examples from the literature that touch on the relevance of the generalized deficit in these contexts are provided, as well as consideration for the continued need to identify specific impairments that are separable from the generalized deficit in order to advance drug and gene discovery.

Assessment of Executive Functions in a Brazilian Sample of Bipolar Subjects

Research has demonstrated impairments in executive functions in Bipolar Mood Disorder patients. Evidence shows that this impairment is present in both periods of active symptoms of the disorder, as well as euthymic stages, and is compounded by mood episodes, especially manic phases. The purpose of this study was to compare the executive performance of a sample of Brazilian bipolar patients in depressive episodes, (44 participants), euthymia (37 participants), and in controls (43 participants). The main instrument for evaluation was the Wisconsin Card Sorting Test. Significant differences were found in performance on the Wisconsin Card Sorting Test between Bipolar subjects (Type I) (both in depression and euthymia) and the controls. No significant correlations were found between the number of manic episodes and the performance on execute measurement variables. The findings suggest that the executive dysfunctions in Bipolar Disorder may be related to both transitory and permanent deficits.

Family history of psychosis negatively impacts age at onset, negative symptoms, and duration of untreated illness and psychosis in first-episode psychosis patients

Family history (FH) of psychosis has been a focus of investigations attempting to explain the heterogeneity in schizophrenia. Previous studies have demonstrated that FH is associated with earlier age at onset, severity of positive and negative symptoms, and the duration of untreated illness (DUI). The current study examined the impact of FH on the clinical presentation and help-seeking behaviors of a well-characterized, first-episode sample. The present study utilized the Symptom Onset in Schizophrenia (SOS) Inventory, the Positive and Negative Syndrome Scale (PANSS), and structured interviews on FH to examine these relationships in a large (n=152) sample of predominantly African American patients. Results showed that patients with a first-degree FH of psychosis had a younger age at onset of both the prodrome and psychosis, but did not differ in duration of prodromal period. Furthermore, FH and sex interacted to influence severity of negative, but not positive symptoms. Finally, FH interacted with sex to influence both the DUI and DUP in that only males with FH had longer DUI and DUP. The findings have implications for understanding the impact of specific family-related mechanisms on both clinical and help-seeking factors, as well as for informing future family-based intervention efforts.

Bipolar disorder: clinical perspectives and implications with cognitive dysfunction and dementia

Introduction. Cognitive dysfunction as a core feature in the course of bipolar affective disorder (BPD) is a current subject of debate and represents an important source of psychosocial and functional burden. Objectives. To stand out the connection and clinical implications between cognitive dysfunction, dementia, and BPD. Methods. A nonsystematic review of all English language PubMed articles published between 1995 and 2011 using the terms "bipolar disorder," "cognitive dysfunction," and "dementia". Discussion. As a manifestation of an affective trait or stage, both in the acute phases and in remission, the domains affected include attention, executive function, and verbal memory. The likely evolution or overlap with the behavioural symptoms of an organic dementia allows it to be considered as a dementia specific to BPD. This is named by some authors, as BPD type VI, but others consider it a form of frontotemporal dementia. It is still not known if this process is neurodevelopmental or neurodegenerative in nature, or both simultaneously. The assessment should consider the iatrogenic effects of medication, the affective symptoms, and a neurocognitive evaluation. Conclusion. More specific neuropsychological tests and functional imaging studies are needed and will assume an important role in the near future for diagnosis and treatment.

Neurocognitive impairment across the bipolar spectrum

Bipolar disorder is a severe mental illness that affects nearly 4.4% of the general population when bipolar spectrum disorders are taken into account. Neurocognitive impairment is thought to be a core deficit of this illness since it is present during euthymia. In fact, 40-60% of euthymic patients present with neurocognitive disturbances. Not only the clinical factors but also disturbances in neurocognition can influence the functional outcome of BD patients. Hence, further research is needed in order to clarify the relationship between these variables. Despite the growing body of evidence that has emerged during the last decade, no unique neurocognitive profile has been proposed yet for either BD subtype. The majority of the studies recluted heterogeneous samples (including both bipolar I and II) or focused on BD-I patients only. The aim of this review is to give an overall picture of the main neurocognitive disturbances found in the bipolar spectrum and particularly in BD-II, where the findings are more ambiguous. An extensive review of all the literature has been done regarding this subtype (from 1980 until July 2009). Data available until now suggest that deficits are present across the bipolar spectrum (BD-I and BD-II), but they seem slightly more severe in BD-I. The extent to which either subtype share-or not-some similarities is still unknown. More studies are required but it would also be interesting to reach a consensus in the neuropsychological assessment of BD to facilitate comparisons between the different studies.

Evolution of neuropsychological dysfunction during the course of schizophrenia and bipolar disorder

BACKGROUND

Neurocognitive dysfunction in schizophrenia (SZ), bipolar (BD) and related disorders represents a core feature of these illnesses, possibly a marker of underlying pathophysiology. Substantial overlap in domains of neuropsychological deficits has been reported among these disorders after illness onset. However, it is unclear whether deficits follow the same longitudinal pre- and post-morbid course across diagnoses. We examine evidence for neurocognitive dysfunction as a core feature of all idiopathic psychotic illnesses, and trace its evolution from pre-morbid and prodromal states through the emergence of overt psychosis and into chronic illness in patients with SZ, BD and related disorders.

METHOD

Articles reporting on neuropsychological functioning in patients with SZ, BD and related disorders before and after illness onset were reviewed. Given the vast literature on these topics and the present focus on cross-diagnostic comparisons, priority was given to primary data papers that assessed cross-diagnostic samples and recent meta-analyses.

RESULTS

Patients with SZ exhibit dysfunction preceding the onset of illness, which becomes more pronounced in the prodrome and early years following diagnosis, then settles into a stable pattern. Patients with BD generally exhibit typical cognitive development pre-morbidly, but demonstrate deficits by first episode that are amplified with worsening symptoms and exacerbations.

CONCLUSIONS

Neuropsychological deficits represent a core feature of SZ and BD; however, their onset and progression differ between diagnostic groups. A lifetime perspective on the evolution of neurocognitive deficits in SZ and BD reveals distinct patterns, and may provide a useful guide to the examination of the pathophysiological processes underpinning these functions across disorders.

Neurocognitive dysfunction in bipolar and schizophrenia spectrum disorders depends on history of psychosis rather than diagnostic group

OBJECTIVES

Neurocognitive dysfunction is milder in bipolar disorders than in schizophrenia spectrum disorders, supporting a dimensional approach to severe mental disorders. The aim of this study was to investigate the role of lifetime history of psychosis for neurocognitive functioning across these disorders. We asked whether neurocognitive dysfunction in bipolar and schizophrenia spectrum disorders depends more on history of psychosis than diagnostic category or subtype.

METHODS

A sample of individuals with schizophrenia (n=102), schizoaffective disorder (n=27), and bipolar disorder (I or II) with history of psychosis (n=75) and without history of psychosis (n=61) and healthy controls (n=280), from a large ongoing study on severe mental disorder, were included. Neurocognitive function was measured with a comprehensive neuropsychological test battery.

RESULTS

Compared with controls, all 3 groups with a history of psychosis performed poorer across neurocognitive measures, while the bipolar group without a history of psychosis was only impaired on a measure of processing speed. The groups with a history of psychosis did not differ from each other but performed poorer than the group without a history of psychosis on a number of neurocognitive measures. These neurocognitive group differences were of a magnitude expected to have clinical significance. In the bipolar sample, history of psychosis explained more of the neurocognitive variance than bipolar diagnostic subtype.

CONCLUSIONS

Our findings suggest that neurocognitive dysfunction in bipolar and schizophrenia spectrum disorders is determined more by history of psychosis than by Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) diagnostic category or subtype, supporting a more dimensional approach in future diagnostic systems.

Cognitive functioning of bipolar I patients and relatives from families with or without schizophrenia or schizoaffective disorder

BACKGROUND

Bipolar I disorder patients show cognitive impairments, and genetic vulnerability to other psychotic disorders may modify these impairments. We set out to assess cognitive functions and estimate their heritability in bipolar I disorder patients (bipolar families) and unaffected relatives in a group of families with bipolar I disorder only and in another group of families with both bipolar I disorder and schizophrenia or schizoaffective disorder (mixed families).

METHODS

A neuropsychological test battery was administered to 20 bipolar patients and 36 relatives from bipolar families, 19 bipolar patients and 28 relatives from mixed families and 55 controls, all representing population-based samples.

RESULTS

Irrespective of the family group, patients and relatives were impaired in psychomotor processing speed. Both patient groups were impaired in executive functioning, but the deficit was more severe in patients from mixed families. Patients from bipolar families scored lower than controls in nearly all measures of verbal memory. All relatives were slightly impaired in executive functioning. The heritability of cognitive functions was generally similar irrespective of psychopathology in the family. However, there were greater genetic effects in several cognitive tasks in mixed families.

LIMITATIONS

The small sample size and familial type of bipolar disorder could limit the generalizability of the results.

CONCLUSION

Impaired psychomotor processing speed and executive functions may represent markers of susceptibility to bipolar I disorder irrespective of psychopathology within the family. Generalized impairment in verbal memory, in turn, may associate more with bipolar disorder than to vulnerability to other psychotic disorders.

Memory functioning in familial bipolar I disorder patients and their relatives

OBJECTIVE

The aim of this study was to compare the memory function of patients with familial bipolar I disorder (BD I) who had shown psychotic features, their non-psychotic, non-bipolar first-degree relatives, and normal controls.

METHOD

We assessed 38 patients with a lifetime diagnosis of BD I who had experienced psychotic symptoms, 49 of their non-psychotic, non-bipolar first-degree relatives, and 44 controls. Patients and relatives were from families multiply affected with functional psychotic illness. A five-subtest short form of the Wechsler Adult Intelligence Scale-Revised and three Wechsler Memory Scale subtests were administered to all participants.

RESULTS

BD I patients showed deficits in verbal memory and verbal learning but not in visual memory. Compared to controls, relatives showed worse verbal learning at a statistically significant or suggestive level and performed significantly worse in both immediate and delayed verbal memory. Similar to patients, there were no differences between the relatives and control group for visual memory.

CONCLUSION

Impaired verbal memory and learning were found in patients and their relatives. These deficits may represent candidate endophenotypic markers for bipolar disorder.

Neurocognitive and clinical predictors of functional outcome in patients with schizophrenia and bipolar I disorder at one-year follow-up

OBJECTIVE

Many studies have reported that cognitive ability may be predictive of the functional outcome for patients with schizophrenia. However, no study has prospectively examined these aspects in schizophrenia and bipolar disorders simultaneously. The present study attempted to analyze if neurocognition and clinical status predicts the real-life functioning for patients with schizophrenia or bipolar I disorder, using a longitudinal design.

METHOD

Forty-seven schizophrenic and 43 bipolar I outpatients were assessed twice with a neurocognitive battery (Executive Functions, Working Memory, Verbal Memory, Visual Memory, Visual-Motor Processing, Vigilance, Vocabulary and Motor Speed tasks), clinical scales (the Positive and Negative Symptom Scale, the Hamilton Rating Scale for Depression and the Clinician Administered Rating Scale for Mania) and functional outcome measures (the Global Assessment of Functioning Scale, the WHO's Disability Assessment Scale and occupational adaptation level) over a one-year follow-up period. The cognitive performance of the patients was compared, at baseline and one year later, with that of 25 healthy subjects.

RESULTS

In schizophrenia patients, global functioning one year later was predicted by a composite neurocognitive score and three specific domain (verbal memory, motor speed, vocabulary). Symptoms appeared to explain less of the variance in functioning. In bipolar I patients, changes in the composite neurocognitive score over one year, deficits in the visual/motor processing domain, severity of symptoms (psychotic, excitatory and affective symptoms) and premorbid adjustment at the first assessment were the variables that better predicted functioning or disability changes over follow-up period.

CONCLUSIONS

Although the relationships between cognition, symptoms and functional capacity differ for schizophrenia or bipolar I patients, neuropsychological performance seems to be a principal longitudinal predictor of functioning in both disorders. Baseline neurocognition and cognitive changes over 12 months predicted changes in functioning over the same period, but only in bipolar I patients. These cognitive domains could be potential neurocognitive endophenotypes (endophenocognitypes) with regard to bipolar I disorder.

Neurocognitive endophenotypes for bipolar disorder

OBJECTIVES

Neurocognitive deficits have been proposed as vulnerability markers or endophenotypes for the development of bipolar I disorder (BD I). However, few research studies have examined whether neurocognitive deficits also exist in first-degree relatives of individuals with BD I.

METHODS

This prospective study examined neurocognitive function in individuals with BD I, their first-degree relatives and a normal control group using a comprehensive battery of neurocognitive tests.

RESULTS

Results indicated that individuals with bipolar disorder and their unaffected relatives demonstrated neuropsychological deficits in comparison to the normal control group in the domains of visuospatial/constructional abilities, executive function, visual learning and memory, and motor speed. In general, the unaffected relatives demonstrated an intermediate level of performance in comparison to the normal control and bipolar group. After adjustment for mood symptoms, significant differences were present for the visuospatial/constructional, executive function, and motor domains. Individuals with bipolar disorder also demonstrated a differential right versus left hemisphere deficit with respect to neurocognitive tasks.

CONCLUSIONS

Results suggest that deficits on specific neuropsychological tests, most notably Digit Symbol, Block Design and Judgment of Line Orientation, may be indicative of cognitive endophenotypes for bipolar disorder. Replication studies are needed to further identify these deficits as endophenotypes for BD I.

The significance of family history in first-episode schizophrenia spectrum disorder

There have been inconsistent findings regarding the significance of family history of schizophrenia spectrum disorders in relation to presentation and course of illness. There has been little research relevant to this issue from first-episode patients. We examined the differences in premorbid adjustment, symptoms, and intellectual functioning between 28 first-episode schizophrenia spectrum patients with a history of such illness in first degree relatives and 28 matched patients without such a family history. The results indicate that whereas the 2 groups did not differ in presenting symptoms, those with a positive family history showed poorer intellectual functioning and less reduction in symptoms at 2 and 3 year follow-up and greater likelihood of abnormal electroencephalogram findings. The findings provide evidence that presence of a positive family history in first-episode patients is associated with a more pernicious form of illness.

The effect of previous psychotic mood episodes on cognitive impairment in euthymic bipolar patients

OBJECTIVES

Cognitive dysfunctions in several domains were proposed to be trait markers of bipolar patients. The aim of this study was to evaluate the effect of previous psychotic features on neuropsychological measures, including sustained attention, in remitted bipolar patients.

METHODS

The study participants were 40 euthymic psychotic, 25 non-psychotic bipolar I patients and 30 healthy control subjects. Participants were assessed with a battery of neuropsychological tests targeting attention, executive functions, psychomotor speed, verbal learning and memory.

RESULTS

Euthymic psychotic bipolar patients performed worse than controls on most of the measures, after controlling for the confounding effects of education, age and residual symptoms. Non-psychotic patients were also impaired on tasks of attention, fluency and psychomotor speed. 'Number of Wisconsin Card Sorting Test (WCST) categories' achieved was the only measure on which psychotic patients performed significantly worse compared to non-psychotic patients. Differences among patient groups were not explained by illness severity measures. The duration of illness was related to slowness in psychomotor speed tasks. Verbal memory deficits may be related to serum lithium levels and age of onset of disease.

CONCLUSIONS

Deficits in cognitive flexibility may be a candidate for being a trait marker of psychotic features among bipolar patients. However, verbal fluency, psychomotor speed and sustained attention deficits may be candidates for vulnerability indicators of bipolar disorder in general.

Context processing performance in bipolar disorder patients

OBJECTIVES

Context processing is the adaptive control of current behavior through the use of prior context information. It has been found to be impaired in schizophrenia. Some studies have indicated that, compared with patients with schizophrenia, those with bipolar disorder (BPD) display a similar but less severe neuropsychological pattern of impairment. However, this cognitive dimension has not yet been examined in BPD patients in the existing literature.

METHODS

An expectancy version of the AX continuous performance test (AX-CPT) was administered to 15 bipolar outpatients and 26 healthy controls. Patients with schizophrenia, in which context processing deficits are known to occur, were used as a reference group.

RESULTS

Bipolar patients showed a context processing deficit relative to healthy controls, although this was less severe and generalized than in schizophrenia patients.

CONCLUSIONS

These findings suggest there are milder impairments in context processing in BPD compared with schizophrenia. However, the severity of possible context processing deficits in BPD may have been underestimated in our sample of mostly euthymic outpatients.

Bipolar I patients with and without a history of psychotic symptoms: do they differ in their cognitive functioning?

Recently, many reports have consistently demonstrated cognitive deficits in patients with bipolar disorder (BD), but their relationship with symptomatology, specifically psychotic symptoms, remains unclear. Our main hypothesis was that a history of hallucinations and/or delusions in the course of BD-I is associated with severe cognitive deficits. We investigated several cognitive functions (memory, attention, verbal fluency and executive functions) in 18 BD-I patients with a history of psychotic symptoms (HPS+), 17 BD-I patients without a history of psychotic symptoms (HPS-), 33 schizophrenic patients and 26 healthy control subjects. Both groups of BD-I patients were more impaired than the normal controls in attention, verbal memory, verbal fluency and executive functions. Only HPS+ BD-I patients showed more difficulties in completing the Stroop test than nonpsychotic bipolar patients. Nevertheless, after adjustment for the effects of current psychopathology, this difference disappeared. Schizophrenic subjects showed worse performance than BD-I subjects in verbal memory and verbal fluency. These results suggest that a history of psychotic symptoms in bipolar I disorder may not be associated with more cognitive deficits. Further research on euthymic bipolar patients with and without HPS is required to confirm these findings.

Neuropsychological symptom dimensions in bipolar disorder and schizophrenia

BACKGROUND

While neurocognitive (NC) impairments have been well documented in schizophrenia (SZ), there is limited data as to whether similar impairments are present in other persistent mental illnesses. Recent data indicate that NC impairments may be manifested in bipolar disorder (BPD) and that they persist across disease states, including euthymia. An important question is whether a comparable structure of NC impairments is present in the 2 diagnostic groups.

OBJECTIVE

In a previous factor analytic study, we identified 6 factors to describe the basic underlying structure of neuropsychological (NP) functioning in SZ: Attention, Working Memory, Learning, Verbal Knowledge, Non-Verbal Functions, Ideational Fluency. The goal of this study was to investigate whether this factor structure is generalizable for BPD.

METHODS

The BPD sample included patients (n = 155) from an ongoing longitudinal study evaluating BPD at the time of hospitalization for relapse and at multiple time points over the following 2 years. The SZ sample included patients (n = 250) from a 3-year study. For the current examination the baseline NP evaluations were selected for both samples.

RESULTS

Exploratory and confirmatory factor analyses in the BPD sample yielded factors similar to those identified in the SZ sample. The coefficients of congruence ranged between 0.66-0.90 for the individual factors, indicating a good overall correspondence between the factor structures in the 2 diagnostic groups. Analysis of covariance (ANCOVA) analysis with education level, full scale-IQ, gender and ethnicity as covariates indicated that SZ patients had markedly worse performance on the Attention and Non-Verbal Functioning factors compared to the BPD patients.

CONCLUSIONS

Together, these data suggest that while the same underlying factor structure describes NP functioning in both groups, the profile of impairments appears to vary with the diagnosis.

Differential working memory impairment in bipolar disorder and schizophrenia: effects of lifetime history of psychosis

BACKGROUND

Although bipolar disorder and schizophrenia have long been viewed as distinct illnesses, there is growing evidence that these two complex diseases share some common genes, which may manifest as overlapping neuropsychological impairments. Although working memory dysfunction has been proposed to be central to the pathophysiology of schizophrenia, it has received less attention in studies of bipolar disorder.

METHOD

We applied measures of working memory to patients with schizophrenia (n = 15), patients with schizoaffective disorder (n = 15), patients with psychotic (n = 11) and non-psychotic (n = 15) bipolar disorder, and demographically matched healthy subjects (n = 32), in order to determine the extent to which these groups show common or unique impairments.

RESULTS

While patients with bipolar disorder (with and without psychotic features) and those with schizophrenia/schizoaffective disorder were impaired on backward digit span, only patients with a lifetime history of psychotic features, regardless of diagnosis, were impaired on spatial delayed response task.

CONCLUSIONS

Backward digit span performance is comparable in bipolar disorder and schizophrenia, and may be an appropriate endophenotypic marker that cuts across diagnostic categories. In contrast, spatial working memory performance clearly distinguishes non-psychotic bipolar disorder patients from patients with functional psychosis.

Neurocognition as a stable endophenotype in bipolar disorder and schizophrenia

Linkage and association studies have paid increasing attention to neurocognition as a putative endophenotype. However, there exists little documentation of its trait stability in schizophrenia or bipolar disorder. Our aim was to determine the longitudinal stability of neurocognitive performance in bipolar versus schizophrenia probands. We administered a neurocognitive battery at two time points, approximately 5 years apart, in 16 schizophrenia and 16 bipolar disorder age-matched subjects. There were no significant changes over time on variables including education, estimated IQ, depression, psychosis, global functioning, or medication status. Schizophrenia subjects showed significant deterioration in one measure of executive functioning but no significant changes in seven of eight other domains. Bipolar patients showed stability over time in attentional measures but greater variability in other domains. These preliminary findings suggest that neurocognitive domains appear longitudinally stable across broad domains in schizophrenia. In contrast, stable functioning may be more limited to attentional domains in bipolar disorder.

Variations in genes regulating neuronal migration predict reduced prefrontal cognition in schizophrenia and bipolar subjects from mediterranean Spain: A preliminary study

Both neural development and prefrontal cortex function are known to be abnormal in schizophrenia and bipolar disorder. In order to test the hypothesis that these features may be related with genes that regulate neuronal migration, we analyzed two genomic regions: the lissencephaly critical region (chromosome 17p) encompassing the LIS1 gene and which is involved in human lissencephaly; and the genes related to the platelet-activating-factor, functionally related to LIS1, in 52 schizophrenic patients, 36 bipolar I patients and 65 normal control subjects. In addition, all patients and the 25 control subjects completed a neuropsychological battery. Thirteen (14.8%) patients showed genetic variations in either two markers related with lissencephaly or in the platelet-activating-factor receptor gene. These patients performed significantly worse in the Wisconsin Card Sorting Test-Perseverative Errors in comparison with patients with no lissencephaly critical region/platelet-activating-factor receptor variations. The presence of lissencephaly critical region/platelet-activating-factor receptor variations was parametrically related to perseverative errors, and this accounted for 17% of the variance (P = 0.0001). Finally, logistic regression showed that poor Wisconsin Card Sorting Test-Perseverative Errors performance was the only predictor of belonging to the positive lissencephaly critical region/platelet-activating-factor receptor group. These preliminary findings suggest that the variations in genes involved in neuronal migration predict the severity of the prefrontal cognitive deficits in both disorders.

Cognitive functioning in patients with schizophrenia and bipolar disorder: a quantitative review

OBJECTIVE

Evidence suggests that cognitive functioning in bipolar disorder may be impaired even in euthymic states, but it is unclear if the pattern of deficits is similar to the deficits found in schizophrenia. The aim of this study was to review quantitatively the studies on cognitive performance in schizophrenia and bipolar disorder.

METHODS

Articles for consideration were identified through a literature search in MEDLINE and PsycLIT in the period between 1985 and October 2004, using the keywords "schizophrenia" combined with "bipolar disorder", or "manic-depress*" or "manic" combined with "cogniti*" or "neuropsycholog*". Thirty-one studies were included that: i) evaluated cognitive performance using standardized and reliable neuropsychological testing procedures; ii) compared adult patients with schizophrenia and with bipolar disorder; iii) reported test scores of both patient groups, or exact p-values, t-values, or F-values; and iv) were published as an original article in a peer-reviewed English language journal.

RESULTS

Meta-analyses of all studies indicated that patients with bipolar disorder generally perform better than patients with schizophrenia, but the distribution of effect sizes showed substantial heterogeneity. Results based on a more homogeneous subset of studies that matched patient groups on clinical and demographic characteristics pointed in the same direction, with effect sizes in the moderate range.

CONCLUSIONS

Patients with bipolar disorder show better cognitive performance than patients with schizophrenia, even when matched for clinical and demographic characteristics.

Neuropsychological dysfunction in bipolar affective disorder: a critical opinion

Data from the imaging literature have led to suggestions that permanent structural brain changes may be associated with bipolar disorder. Individuals diagnosed with bipolar disorder display deficits on a range of neuropsychological tasks in both the acute and euthymic phases of illness, and correlations between experienced number of affective episodes and task performance are commonly reported. These findings have renewed interest in the neuropsychological profile of individuals with bipolar disorder, with deficits of attention, learning and memory, and executive function, asserted to be present. This paper critically reviews five different potential causes of neurocognitive dysfunction in bipolar disorder: (i) iatrogenic, (ii) acute functional changes associated with depression or mania, (iii) permanent structural lesions of a neurodegenerative origin, (iv) permanent structural lesions that are neurodevelopmental in origin, and (v) permanent functional changes that are most likely genetic in origin. Although the potential cognitive effects of residual symptomatology and long-term medication use cannot be entirely excluded, we conclude that functional changes associated with genetically driven population variation in critical neural networks underpin both the neurocognitive and affective symptoms of bipolar disorder. The philosophical implications of this conclusion for neuropsychology are briefly discussed.

Effects of adjunctive mifepristone (RU-486) administration on neurocognitive function and symptoms in schizophrenia

BACKGROUND

It has been suggested that hypercortisolemia may cause or exacerbate both neurocognitive impairment and symptoms in schizophrenia. We hypothesized that antiglucocorticoid treatments, particularly glucocorticoid receptor (GR) antagonists, would improve neurocognitive functioning and clinical symptoms in this disorder.

METHOD

Twenty patients with schizophrenia were treated with 600 mg/day of the GR-antagonist mifepristone (RU-486) or placebo for 1 week in a double-blind, crossover design. Neurocognitive function was evaluated at baseline and 2 weeks after each treatment. Neuroendocrine profiling was performed at these times and also immediately after each treatment. Symptoms were evaluated weekly.

RESULTS

Mifepristone administration resulted in a temporary two- to threefold increase in plasma cortisol levels (p < .0001). No significant effects were observed on any measure of neurocognitive function, including the primary outcome measures of spatial working memory and declarative memory. Minor changes in symptoms occurred in both arms of the study and were indicative of a general improvement over time, irrespective of treatment.

CONCLUSIONS

In contrast to our earlier report of positive effects in bipolar disorder, these data suggest that the GR-antagonist mifepristone has no effect on neurocognitive function or symptoms in this group of patients with schizophrenia. Future studies in schizophrenia should examine patients with demonstrable hypothalmic-pituitary-adrenal axis dysfunction.

Are there attentional deficits in people putatively at risk for affective disorders?

BACKGROUND

Schizophrenia is associated with attentional dysfunctions. In bipolar disorder, there is also evidence for sustained attention deficits. Therefore, we hypothesized that risk for bipolar disorder but not for unipolar depression might be associated with attentional abnormalities as well.

METHOD

Using the Hypomanic Personality Scale (HPS) and the Rigidity Scale, we defined three groups: bipolar at-risk (n=42), unipolar at-risk (n=34), and control (n=37). All completed the d2 Test and the Continuous Performance Test (CPT).

RESULTS

There was no evidence for overall attentional deficits in people at risk for affective disorders. However, reduced sensitivity, i.e., less discrimination between targets and nontargets, was observed in people at risk for bipolar disorders who also displayed schizotypy.

LIMITATIONS

We only looked at selective and sustained attention and did not assess other factors such as memory or executive functions. Additionally, the risk status was only defined by a psychometric indicator and did not include other approaches of defining risk (e.g., first-degree relatives).

CONCLUSIONS

Despite some limitations, our results support on one hand the idea that vulnerability for bipolar disorder can be associated with cognitive impairments, but they also highlight that this is not generally the case. Vulnerability for bipolar disorder and schizotypy might be correlated but are not the same.