A 2-year naturalistic study on cognitive functioning in bipolar disorder

Sustained attention in psychosis: Neuroimaging findings

To provide a systematic review of scientific literature on functional magnetic resonance imaging (fMRI) studies on sustained attention in psychosis. We searched PubMed to identify fMRI studies pertaining sustained attention in both affective and non-affective psychosis. Only studies conducted on adult patients using a sustained attention task during fMRI scanning were included in the final review. The search was conducted on September 10^th, 2013. 15 fMRI studies met our inclusion criteria: 12 studies were focused on Schizophrenia and 3 on Bipolar Disorder Type I (BDI). Only half of the Schizophrenia studies and two of the BDI studies reported behavioral abnormalities, but all of them evidenced significant functional differences in brain regions related to the sustained attention system. Altered functioning of the insula was found in both Schizophrenia and BDI, and therefore proposed as a candidate trait marker for psychosis in general. On the other hand, other brain regions were differently impaired in affective and non-affective psychosis: alterations of cingulate cortex and thalamus seemed to be more common in Schizophrenia and amygdala dysfunctions in BDI. Neural correlates of sustained attention seem to be of great interest in the study of psychosis, highlighting differences and similarities between Schizophrenia and BDI.

Using the Brief Assessment of Cognition in Schizophrenia (BACS) to assess cognitive impairment in older patients with schizophrenia and bipolar disorder

OBJECTIVES

A growing body of evidence suggests that impairment in cognitive functioning is an important clinical feature of both schizophrenia and bipolar disorder, and that these cognitive alterations worsen with age. Although cognitive assessments are increasingly becoming a part of research and clinical practice in schizophrenia, a standardized and easily administered test battery for elderly patients with bipolar disorder is still lacking. The Brief Assessment of Cognition in Schizophrenia (BACS) captures those domains of cognition that are the most severely affected in patients with schizophrenia and the most strongly correlated with functional outcome. The primary aim of our study was to investigate the clinical usefulness of the BACS in assessing cognitive functioning in elderly euthymic patients with bipolar disorder, and to compare their cognitive profile to that of elderly patients with schizophrenia.

METHODS

Elderly euthymic patients with bipolar disorder or schizophrenia were assessed using the BACS and a standard cognitive test battery.

RESULTS

Fifty-seven elderly patients (aged 60 years and older) with bipolar disorder (n = 42) or schizophrenia (n = 15) were invited to participate. All of the patients were assessed by the BACS as being cognitively impaired. The patients with bipolar disorder scored significantly higher on the global scale and the verbal memory and attention sub-scores of the BACS than the patients with schizophrenia.

DISCUSSION

The BACS appears to be a feasible and informative cognitive assessment tool for elderly patients with bipolar disorder. We believe that these preliminary results merit further investigation.

Neuropathological and neuromorphometric abnormalities in bipolar disorder: view from the medial prefrontal cortical network

The question of whether BD is primarily a developmental disorder or a progressive, neurodegenerative disorder remains unresolved. Here, we review the morphometric postmortem and neuroimaging literature relevant to the neuropathology of bipolar disorder (BD). We focus on the medial prefrontal cortex (mPFC) network, a key system in the regulation of emotional, behavioral, endocrine, and innate immunological responses to stress. We draw four main conclusions: the mPFC is characterized by (1) a decrease in volume, (2) reductions in neuronal size, and/or changes in neuronal density, (3) reductions in glial cell density, and (4) changes in gene expression. These data suggest the presence of dendritic atrophy of neurons and the loss of oligodendroglial cells in BD, although some data additionally suggest a reduction in the cell counts of specific subpopulations of GABAergic interneurons. Based on the weight of the postmortem and neuroimaging literature discussed herein, we favor a complex hypothesis that BD primarily constitutes a developmental disorder, but that additional, progressive, histopathological processes also are associated with recurrent or chronic illness. Conceivably BD may be best conceptualized as a progressive neurodevelopmental disorder.

12-month longitudinal cognitive functioning in patients recently diagnosed with bipolar disorder

OBJECTIVES

Although cognitive deficits are observed in the early stages of bipolar disorder, the longitudinal course of neuropsychological functioning during this period is unknown. Such knowledge could provide etiologic clues into the cognitive deficits associated with the illness, and could inform early treatment interventions. The purpose of the present study was to evaluate cognitive change in bipolar disorder in the first year after the initial manic episode.

METHODS

From an initial pool of 65 newly diagnosed patients with bipolar disorder (within three months of the end of the first manic or mixed episode) and 36 demographically similar healthy participants, 42 patients [mean age 22.9 years, standard deviation (SD) = 4.0] and 23 healthy participants [mean age 22.9 years (SD = 4.9)] completed baseline, six-month, and one-year neuropsychological assessments of multiple domains including processing speed, attention, verbal and nonverbal memory, working memory, and executive function. Patients also received clinical assessments, including mood ratings.

RESULTS

Although patients showed consistently poorer cognitive performance than healthy individuals in most cognitive domains, patients showed a linear improvement over time in processing speed (p = 0.008) and executive function (p = 0.004) relative to the comparison group. Among patients, those without a history of alcohol/substance abuse or who were taken off an antipsychotic treatment during the study showed better improvement.

CONCLUSIONS

The early course of cognitive functioning in bipolar disorder is likely influenced by multiple factors. Nevertheless, patients with bipolar disorder showed select cognitive improvements in the first year after resolution of their initial manic episode. Several clinical variables were associated with better recovery, including absence of substance abuse and discontinuation of antipsychotic treatment during the study. These and other factors require further investigation to better understand their contributions to longitudinal cognitive functioning in early bipolar disorder.

Glycogen synthase kinase-3 inhibitors: Rescuers of cognitive impairments

Impairment of cognitive processes is a devastating outcome of many diseases, injuries, and drugs affecting the central nervous system (CNS). Most often, very little can be done by available therapeutic interventions to improve cognitive functions. Here we review evidence that inhibition of glycogen synthase kinase-3 (GSK3) ameliorates cognitive deficits in a wide variety of animal models of CNS diseases, including Alzheimer's disease, Fragile X syndrome, Down syndrome, Parkinson's disease, spinocerebellar ataxia type 1, traumatic brain injury, and others. GSK3 inhibitors also improve cognition following impairments caused by therapeutic interventions, such as cranial irradiation for brain tumors. These findings demonstrate that GSK3 inhibitors are able to ameliorate cognitive impairments caused by a diverse array of diseases, injury, and treatments. The improvements in impaired cognition instilled by administration of GSK3 inhibitors appear to involve a variety of different mechanisms, such as supporting long-term potentiation and diminishing long-term depression, promotion of neurogenesis, reduction of inflammation, and increasing a number of neuroprotective mechanisms. The potential for GSK3 inhibitors to repair cognitive deficits associated with many conditions warrants further investigation of their potential for therapeutic interventions, particularly considering the current dearth of treatments available to reduce loss of cognitive functions.

A longitudinal study of cognition in asymptomatic and mildly symptomatic bipolar disorder patients

Bipolar disorder (BD) is characterized by cognitive deficits that impair patients' functioning and quality of life. Most of the earlier studies assessing changes in BD patients' cognitive functioning over time utilized a cross-sectional research design. The few longitudinal studies that were conducted tended to have methodological limitations such as very short follow-up periods, recruitment of acutely ill patients, and lack of assessment of practice effects. The current study aimed to assess changes over time in the cognitive functioning of typical BD outpatients. For this purpose, asymptomatic and mildly symptomatic BD outpatients were assessed at baseline and after two years (n=31). At baseline, the cognitive functioning of the BD patients was compared to that of gender- and age-matched healthy controls. Practice effects were estimated by re-assessing the controls one week after their first assessment. Compared to the controls, BD patients had deficits in psychomotor speed, sustained attention, and one domain of executive functioning (cognitive planning). No evidence was found of a decline in their cognitive functioning over the two year time interval. These findings support a developmental model of cognitive impairment in BD. Studies using longer follow-up periods and larger sample sizes, however, are needed before these conclusions can be stated confidently.

[Neurocognitive fuctioning in pure mania and mixed mania]

Neurocognitive dysfunction is increasingly recognized as a prominent feature of bipolar disorder. Cognitive function seems to be impaired across different states of bipolar illness. Nervertheless, research that studies neuropsychological functioning in acute phases is scarce. Acutely ill patients have shown dysfunctions in several cognitive areas. We reviewed the literature on neuropsychological studies of acute phases to highlight neurocognitive deficits in mixed and pure mania. The results show dysfunctions in sustained attention that are significantly more important in mixed mania rather than in pure mania. Impulsive pattern of responding seems to characterize pure manic state. We also found impairments in processing speed, verbal and spatial learning/memory and executive functions, including cognitive flexibility, inhibitory control, conceptual reasoning, planning and problem solving. Disturbance in executive functioning seems to be more important in pure mania rather than mixed mania.

Effects of cognitive remediation on cognitive dysfunction in partially or fully remitted patients with bipolar disorder: study protocol for a randomized controlled trial

BACKGROUND

A large proportion of patients with bipolar disorder experience persistent cognitive dysfunction, such as memory, attention and planning difficulties, even during periods of full remission. The aim of this trial is to investigate whether cognitive remediation, a new psychological treatment, improves cognitive function and, in turn, psychosocial function in patients with bipolar disorder in partial or full remission.

METHODS/DESIGN

The trial has an evaluator-blind, randomized, between-groups design. Forty patients with bipolar disorder in full or partial remission, aged 18 to 50 years, who report moderate to severe cognitive difficulties, are recruited. Patients are randomized to receive weekly group-based cognitive remediation treatment over 12 weeks in addition to standard treatment or standard treatment alone. Both groups undergo neurocognitive testing and functional magnetic resonance imaging (fMRI) at baseline, post-treatment (week 12) and follow-up (week 26). The primary outcome is improved verbal memory, as measured with the Rey Auditory Verbal Learning Test (RAVLT) from baseline to post-treatment. With inclusion of 40 patients we obtain 86% power to detect a clinically relevant difference in verbal memory between groups. Secondary outcomes are improved attention, executive function and psychosocial function, as measured with the Rapid Visual Information Processing test, the Trail Making Test part B and the Functional Assessment Short Test (FAST), respectively. Tertiary outcomes are improved scores for additional neuropsychological tests of memory, attention, executive function and facial expression recognition, as well as in questionnaires measuring subjective cognitive difficulties, stress, coping strategies, personality traits, depressive symptoms and quality of life.

DISCUSSION

This is the first randomized controlled trial to evaluate the effects of cognitive remediation on cognitive function in patients with bipolar disorder who experience persistent cognitive difficulties despite being in full or partial remission.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01457235.

The CACNA1C risk allele selectively impacts on executive function in bipolar type I disorder

OBJECTIVE

Calcium channels are important for converting electrical activity into biochemical events. A single nucleotide polymorphism (SNP) (rs1006737) in the CACNA1C gene has been strongly associated with increased risk for Bipolar disorder (BD) in genome-wide association studies. Recently, this same SNP has been reported to influence executive function in schizophrenia and controls, but it remains unclear whether this SNP affects behaviour, especially cognition in subjects with BD.

METHOD

A total of 109 BD type I subjects and 96 controls were genotyped for CACNA1C rs1006737 and assessed with an executive function tests battery [Wechsler Adult Intelligence Scale III (WAIS-III) Letter-Number Sequence subtest (WAIS-LNS), digit span (WAISDS), trail making test (TMT), and WCST (Wisconsin Card Sorting Test)].

RESULTS

In patients with BD, the CACNA1C genotype Met/Met was associated with worse performance on all four executive function tests compared to Val/Val. No influence of CACNA1C was observed in the cognitive performance of healthy controls.

CONCLUSION

Our data indicate for the first time that the CACNA1C risk allele is likely associated with executive dysfunction as a trait in BD, as this association was found regardless the presence of mood symptoms. Larger studies should evaluate the potential influence of CACNA1C on other cognitive domains in BD.

Is the non-verbal behavioural emotion-processing profile of bipolar disorder impaired? A critical review

OBJECTIVE

Growing evidence suggests that patients with bipolar disorder (BD) are impaired in their ability to process non-verbal emotion, although few comprehensive reviews of the behavioural literature exist, and there has been little consideration of methodological issues that may account for discrepant empirical findings. This review examines the behavioural facial, prosodic and multimodal processing literature in BD and discusses methodological issues in the context of this evidence.

METHOD

Major computer databases including Google Scholar and PsychINFO were consulted to conduct a comprehensive review of quantitative behavioural differences in the emotion-processing literature in BD. Articles were accepted only if the target population sample met criteria for a DSM-III, DSM-IV or ICD-10 diagnosis, and they contained a healthy control group.

RESULTS

The current literature suggests that facial emotion processing is impaired, and there is preliminary evidence for some behavioural impairment in the processing of emotional prosody.

CONCLUSION

The specificity or generalisability of impairments in facial emotion processing and the effects of mood state are unclear. Similarly, the lack of clarity around the impact of auditory processes on emotional prosody processing warrants a comprehensive examination of the auditory profile in BD.

Validity and reliability of a rating scale on subjective cognitive deficits in bipolar disorder (COBRA)

BACKGROUND

Discrepancies between bipolar patients' reports and neuropsychological testing have been described and replicated. Unfortunately, no valid, specific, user-friendly, brief instrument is available to measure cognitive deficits as reported by these patients. The main aim of this study was to validate a novel instrument named the "cognitive complaints in bipolar disorder rating assessment" (COBRA). Second, we investigated the relationship between the COBRA, objective cognitive measures and illness course variables.

METHOD

The total sample (N=215) included 91 bipolar disorder patients and 124 healthy controls. The psychometric properties of the COBRA (e.g. internal consistency, concurrent validity, discriminative validity, factorial analyses, ROC curve and feasibility) were analyzed. A complete neuropsychological battery was used as objective cognitive assessment.

RESULTS

The COBRA had one-factor structure with very high internal consistency (Cronbach's alpha=0.913). A high convergent validity was indicated by a strong correlation with the Frankfurt Complaint Questionnaire (ro=0.888, p<0.001). Bipolar patients experienced greater cognitive complaints compared to control group suggesting a discriminative validity of the instrument. Significant correlations were found between the COBRA and some objective cognitive measures. Furthermore, higher COBRA scores were associated with bipolar II subtype, residual depressive symptoms, hypomanic episodes and total episodes.

LIMITATIONS

The cross-sectional design of the study, the influence of medication and severity of patients included.

CONCLUSIONS

The COBRA showed to be a useful instrument to assess overall cognitive complaints in bipolar disorder with very satisfactory psychometric properties. Cognitive complaints were partially correlated with memory and executive function measures and with issues that may increase the subjective perception of cognitive deficits, such as subthreshold depressive symptoms and number of episodes.

Neurocognitive function in bipolar disorder: a comparison between bipolar I and II disorder and matched controls

BACKGROUND

Cognitive deficits have been documented in patients with bipolar disorder. Further, it has been suggested that the degree and type of cognitive impairment differ between bipolar I and bipolar II disorder, but data is conflicting and remains inconclusive. This study aimed to clarify the suggested differences in cognitive impairment between patients with bipolar I and II disorder in a relatively large, clinically stable sample while controlling for potential confounders.

METHODS

67 patients with bipolar I disorder, 43 with bipolar II disorder, and 86 randomly selected population-based healthy controls were compared. A number of neuropsychological tests were administered, assessing verbal and visual memory and executive functions. Patients were in a stable phase during testing.

RESULTS

Patients with bipolar type I and type II were cognitively impaired compared to healthy controls, but there were no statistically significant differences between the two subtypes. The strongest predictor of cognitive impairment within the patient group was current antipsychotic treatment.

CONCLUSIONS

The present study suggests that the type and degree of cognitive dysfunction is similar in bipolar I and II patients. Notably, treatment with antipsychotics - but not a history of psychosis - was associated with more severe cognitive impairment. Given that patients with bipolar I disorder are more likely to be on antipsychotic drugs, this might explain why some previous studies have found that patients with type I bipolar disorder are more cognitively impaired than those with type II.

Genetic and neurocognitive foundations of emotion abnormalities in bipolar disorder

INTRODUCTION

Bipolar Disorder (BD) is a serious mood disorder, the aetiology of which is still unclear. The disorder is characterised by extreme mood variability in which patients fluctuate between markedly euphoric, irritable, and elevated states to periods of severe depression. The current research literature shows that BD patients demonstrate compromised neurocognitive ability in addition to these mood symptoms. Viable candidate genes implicated in neurocognitive and socioemotional processes may explain the development of these core emotion abnormalities. Additionally, links between faulty neurocognition and impaired socioemotional ability complement genetic explanations of BD pathogenesis. This review examines associations between cognition indexing prefrontal neural regions and socioemotional impairments including emotion processing and regulation. A review of the effect of COMT and TPH2 on these functions is also explored.

METHODS

Major computer databases including PsycINFO, Google Scholar, and Medline were consulted in order to conduct a comprehensive review of the genetic and cognitive literature in BD.

RESULTS

This review determines that COMT and TPH2 genetic variants contribute susceptibility to abnormal prefrontal neurocognitive function which oversees the processing and regulation of emotion. This provides for greater understanding of some of the emotional and cognitive symptoms in BD.

CONCLUSIONS

Current findings in this direction show promise, although the literature is still in its infancy and further empirical research is required to investigate these links explicitly.

Working memory as a predictor of negative symptoms and functional outcome in first episode psychosis

The relationship of neurocognitive course with clinical and functional outcomes in psychosis is not well known, especially in the long term. The aim of the study was to examine the clinical and neuropsychological course of first-episode psychosis patients at 5-year follow-up and analyze the relationship of cognitive performance with clinical and functional outcome. The 5-year follow-up was conducted with 26 first-episode psychosis patients. Psychotic symptoms were measured by the Positive and Negative Syndrome Scale, manic and depressive symptoms by the Young Mania Rating Scale and Hamilton Depression Rating Scale respectively, and psychosocial functioning by the Functioning Assessment Short Test. The cognitive domains were assessed by the Wechsler Adult Intelligence Scale, the Wisconsin Card Sorting Test, the Trail Making Test, the Verbal Fluency Test, the Stroop Colour-Word Test and the Wechsler Memory Scale. Patients showed symptomatic improvement in the follow-up except in negative psychotic symptoms. There was also improvement in most cognitive domains except in working memory and processing speed in the follow-up. Working memory impairment was associated to negative psychotic symptoms and poor functional outcomes. Negative symptoms mediated the relationship between working memory and outcome. Therefore, negative symptoms should be a primary target of treatment to improve functional outcomes.

Antipsychotic medications and cognitive functioning in bipolar disorder: moderating effects of COMT Val108/158 Met genotype

BACKGROUND

There is a negative association between the use of antipsychotics and cognitive functioning in bipolar patients, which may be mediated by altered dopamine signaling in selected brain areas, and moderation thereof by genetic sequence variation such as COMT Val108/158Met. The interaction between antipsychotic drug use and the COMT Val108/158Met genotype on two-year cognitive functioning in bipolar patients was examined.

METHODS

Interaction between the COMT Val108/158Met and antipsychotics on a composite cognitive measure was examined in 51 bipolar patients who were assessed 12 times at two-monthly intervals over a period of two years (379 observations).

RESULTS

There was a significant negative effect of the interaction between antipsychotic medications and Val allele load on the composite cognitive measure in bipolar patients (p < 0.001).

CONCLUSIONS

The negative effects of antipsychotics on cognitive functioning in bipolar disorder may be moderated by the COMT Val 108/158 Met genotype, with a negative effect of Val allele load. If replicated, the results may be indicative of pharmacogenetic interactions in bipolar disorder.

Potential mechanisms of action of lithium in bipolar disorder. Current understanding

Lithium has been used for over half a century for the treatment of bipolar disorder as the archetypal mood stabilizer, and has a wealth of empirical evidence supporting its efficacy in this role. Despite this, the specific mechanisms by which lithium exerts its mood-stabilizing effects are not well understood. Given the inherently complex nature of the pathophysiology of bipolar disorder, this paper aims to capture what is known about the actions of lithium ranging from macroscopic changes in mood, cognition and brain structure, to its effects at the microscopic level on neurotransmission and intracellular and molecular pathways. A comprehensive literature search of databases including MEDLINE, EMBASE and PsycINFO was conducted using relevant keywords and the findings from the literature were then reviewed and synthesized. Numerous studies report that lithium is effective in the treatment of acute mania and for the long-term maintenance of mood and prophylaxis; in comparison, evidence for its efficacy in depression is modest. However, lithium possesses unique anti-suicidal properties that set it apart from other agents. With respect to cognition, studies suggest that lithium may reduce cognitive decline in patients; however, these findings require further investigation using both neuropsychological and functional neuroimaging probes. Interestingly, lithium appears to preserve or increase the volume of brain structures involved in emotional regulation such as the prefrontal cortex, hippocampus and amygdala, possibly reflecting its neuroprotective effects. At a neuronal level, lithium reduces excitatory (dopamine and glutamate) but increases inhibitory (GABA) neurotransmission; however, these broad effects are underpinned by complex neurotransmitter systems that strive to achieve homeostasis by way of compensatory changes. For example, at an intracellular and molecular level, lithium targets second-messenger systems that further modulate neurotransmission. For instance, the effects of lithium on the adenyl cyclase and phospho-inositide pathways, as well as protein kinase C, may serve to dampen excessive excitatory neurotransmission. In addition to these many putative mechanisms, it has also been proposed that the neuroprotective effects of lithium are key to its therapeutic actions. In this regard, lithium has been shown to reduce the oxidative stress that occurs with multiple episodes of mania and depression. Further, it increases protective proteins such as brain-derived neurotrophic factor and B-cell lymphoma 2, and reduces apoptotic processes through inhibition of glycogen synthase kinase 3 and autophagy. Overall, it is clear that the processes which underpin the therapeutic actions of lithium are sophisticated and most likely inter-related.

Sleep disturbance and cognitive deficits in bipolar disorder: toward an integrated examination of disorder maintenance and functional impairment

Bipolar disorder is frequently associated with a number of poor outcomes including, but not limited to, a significant impairment in the ability to return to premorbid levels of occupational and psychosocial functioning, often despite the remission of mood symptoms. Sleep disturbance is an oft-reported residual symptom of manic and depressive episodes that has likewise been associated with the onset of manic episodes. Also present during affective episodes as well as the inter-episode periods are reports of deficits in cognitive functioning, which many reports have shown to play an important role in this persistent disability. Despite the presence of deficits in these two domains of functioning during affective episodes as well as the inter-episode phase, there has been no evaluation of the degree to which these systems may interact to maintain such high rates of functional disability. The aim of this review is to examine evidence for the study of the relationship between sleep disturbance and cognitive impairments in bipolar disorder as well as the ways in which deficits in these domains may work together to maintain functional impairment.

Neurocognitive Functioning in Schizophrenia and Bipolar Disorder: Clarifying Concepts of Diagnostic Dichotomy vs. Continuum

The Kraepelinian dichotomy posits that patients with schizophrenia (SCZ) and bipolar disorder (BD) present as two separate psychotic entities such that they differ in terms of clinical severity including neurocognitive functioning. Our study aimed to specifically compare and contrast the level of neurocognitive functioning between SCZ and BD patients and identify predictors of their poor neurocognitive functioning. We hypothesized that patients with SCZ had a similar level of neurocognitive impairment compared with BD. About 49 healthy controls (HC), 72 SCZ, and 42 BD patients who were matched for age, gender, and premorbid IQ were administered the Brief Assessment of Cognition battery (BAC). Severity of psychopathology and socio-occupational functioning were assessed for both patients groups. Both BD and SCZ groups demonstrated similar patterns of neurocognitive deficits across several domains (verbal memory, working memory, semantic fluency, processing speed) compared with HC subjects. However, no significant difference was found in neurocognitive functioning between BD and SCZ patients, suggesting that both patient groups suffer the same degree of neurocognitive impairment. Patients with lower level of psychosocial functioning [F (1,112) = 2.661, p = 0.009] and older age [F (1,112) = -2.625, p = 0.010], not diagnosis or doses of psychotropic medications, predicted poorer overall neurocognitive functioning as measured by the lower BAC composite score. Our findings of comparable neurocognitive impairments between SCZ and BD affirm our hypothesis and support less the Kraepelinian concept of dichotomy but more of a continuum of psychotic spectrum conditions. This should urge clinicians to investigate further the underlying neural basis of these neurocognitive deficits, and be attentive to the associated socio-demographic and clinical profile in order to recognize and optimize early the management of the widespread neurocognitive deficits in patients with SCZ and BD.

Cognitive processes and attitudes in bipolar disorder: a study into personality, dysfunctional attitudes and attention bias in patients with bipolar disorder and their relatives

BACKGROUND

Research in cognitive processes and attitudes in bipolar disorder is scarce and has provided mixed findings, possibly due to differences in current mood state. It is unclear whether alterations in cognitive processes and attitudes are only related to the depressive mood states of bipolar patients or also represent a vulnerability marker for the development of future (depressive) episodes. This was investigated in the current study.

METHODS

Both implicit (attentional bias for emotional words) and explicit (dysfunctional attitudes and personality characteristics) measures of cognitive processes and attitudes were assessed in 77 bipolar patients with varying levels of depressive symptoms (depressed=17, euthymic n=60), their healthy first-degree relatives (n=39) and a healthy control group (n=61). Analyses of variance were used to investigate differences between groups.

RESULTS

Mildly depressed patients with bipolar disorder demonstrated an attentional bias away from positive emotional words and showed increased dysfunctional attitudes and higher levels of neuroticism. Euthymic patients were largely comparable to healthy controls and only differed from controls in higher levels of neuroticism. Relatives were similar to controls on all measures, although they significantly differed from bipolar patients in displaying less neuroticism and more extraversion.

LIMITATIONS

No firm conclusions regarding causality can be drawn from the associations that were found between cognitive processes and attitudes and the evolution of mood symptoms in bipolar disorder.

CONCLUSION

Alterations in cognitive processes and attitudes in bipolar patients appear to be mostly related to the expression of mood symptomatology rather than to the vulnerability for bipolar disorder.

Pharmacological approaches in bipolar disorders and the impact on cognition: a critical overview

OBJECTIVE

Historically, pharmacological treatments for bipolar disorders (BD) have been associated with neurocognitive side-effects. We reviewed studies which assessed the impact of several psychopharmacological drugs on the neurocognitive function of BD patients.

METHOD

The PubMed database was searched for studies published between January 1980 and February 2011, using the following terms: bipolar, bipolar disorder, mania, manic episode, or bipolar depression, cross-referenced with cognitive, neurocognitive, or neuropsychological, cross-referenced with treatment.

RESULTS

Despite methodological flaws in the older studies and insufficient research concerning the newer agents, some consistent findings emerged from the review; lithium appears to have definite, yet subtle, negative effects on psychomotor speed and verbal memory. Among the newer anticonvulsants, lamotrigine appears to have a better cognitive profile than carbamazepine, valproate, topiramate, and zonisamide. More long-term studies are needed to better understand the impact of atypical antipsychotics on BD patients' neurocognitive functioning, both in monotherapy and in association with other drugs. Other agents, like antidepressants and cognitive enhancers, have not been adequately studied in BD so far.

CONCLUSION

Pharmacotherapies for BD should be chosen to minimize neurocognitive side-effects, which may already be compromised by the disease process itself. Neurocognitive evaluation should be considered in BD patients to better evaluate treatment impact on neurocognition. A comprehensive neuropsychological evaluation also addressing potential variables and key aspects such as more severe cognitive deficits, comorbidities, differential diagnosis, and evaluation of multiple cognitive domains in longitudinal follow-up studies are warranted.

Linguistic production and syntactic comprehension in schizophrenia and bipolar disorder

OBJECTIVE

To explore linguistic abilities in schizophrenia and bipolar disorder. Specifically, the aims of this study were to: i) investigate microlinguistic (lexicon, morphology, syntax) and macrolinguistic (discourse coherence, pragmatics) dimensions of speech production and ii) evaluate syntactic comprehension skills in both schizophrenia and bipolar disorder.

METHOD

Linguistic performance of 30 Italian-speaking patients with schizophrenia, 30 participants with bipolar disorder and 30 healthy controls comparable for age and educational level has been assessed using a story-telling task and a computer-based test of syntactic comprehension.

RESULTS

In narrative production, compared with healthy participants, those with schizophrenia had slight problems in speech rate and deficits at both local and global discourse coherence, whereas patients with bipolar disorder showed reduced mean length of utterance. As regards syntactic comprehension, both groups of patients collected more grammatical errors than controls, but they differed with regard to the number and kind of grammatical construction they missed.

CONCLUSION

Linguistic deficits have been detected in both groups of patients, being, however, more severe and generalized in schizophrenia than in bipolar disorder. Such results help us in improving our understanding of the potential psychopathological overlapping between these disorders.

Cognitive functioning and age at onset in non-affective psychotic disorder

OBJECTIVE

Age at psychosis onset has been related to variability in cognitive functioning, but its effect may be mediated by demographic and clinical factors. The aim of the current study was to study the contribution of age at onset, as well as demographic and illness characteristics, to variation in cognitive functioning in patients with schizophrenia spectrum disorder.

METHOD

Patients (n = 1053) and healthy controls (n = 631) underwent comprehensive neuropsychological and clinical assessments. The effect of age at onset on age-standardized cognitive test scores was assessed with multiple linear regression analyses. Mediation by illness and demographic factors was tested using a multiple mediation Sobel test.

RESULTS

A diagnosis of schizophrenia, higher antipsychotic dose, and more negative symptoms were associated with earlier onset of illness, while female sex and a more chronic course were associated with later illness onset. Furthermore, earlier onset was associated with worse performance on immediate recall and sustained attention. However, male sex, more negative symptoms, and higher antipsychotic dose mediated the effect of age at onset on memory, while negative symptoms explained its association with attention/vigilance.

CONCLUSION

Greater impairment in memory and attention in early-onset psychosis may be explained by features indicative of underlying neurodevelopmental vulnerability.

Is there an association between subjective and objective measures of cognitive function in patients with affective disorders?

BACKGROUND

Patients with affective disorders experience cognitive dysfunction in addition to their affective symptoms. The relationship between subjectively experienced and objectively measured cognitive function is controversial with several studies reporting no correlation between subjective and objective deficits.

AIMS

To investigate whether there is a correlation between subjectively reported and objectively measured cognitive function in patients with affective disorders, and whether subjective complaints predict objectively measured dysfunction.

METHODS

The study included 45 participants; 15 with bipolar disorder (BD), 15 with unipolar disorder (UD) and 15 healthy individuals. Participants' subjectively experienced cognitive function and objective cognitive function were assessed with the Massachusetts General Hospital Cognitive and Physical Functioning Questionnaire (CPFQ) and the Screen for Cognitive Impairment in Psychiatry (SCIP), respectively. Patients were rated for affective symptoms with Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS).

RESULTS

Patients demonstrated subjective and objective cognitive dysfunction relative to controls (P-values ≤ 0.01) but there were no differences between patient groups (P > 0.1). We found no correlation between subjectively experienced and objectively measured cognitive dysfunction in BD (P = 0.7), and a non-significant trend towards a correlation in UD (P = 0.06), which disappeared when controlling for gender (P = 0.1).

CONCLUSION

Our results suggest that it is not necessarily patients who have cognitive complaints that are most impaired. If confirmed in a larger sample, our findings suggest that neuropsychological assessment is warranted to elucidate the potential role of cognitive dysfunction in patients' everyday lives and to inform treatment strategies targeting these difficulties.

COMT polymorphisms as predictors of cognitive dysfunction during manic and mixed episodes in bipolar I disorder

OBJECTIVE

The dopaminergic system plays an important role in the prefrontal cortex (PFC) and is believed to mediate cognitive dysfunction (CD) in bipolar disorder (BD). The enzyme catechol-O-methyltransferase (COMT) is involved in the catabolism of dopamine in the PFC, and an association between COMT single nucleotide polymorphisms (SNPs) and BD has been reported. COMT SNPs have also been associated with executive and working memory performance in healthy subjects, patients with schizophrenia, and euthymic BD patients. The objective of this study was to investigate the association between COMT SNPs and acute CD during BD mood episodes.

METHODS

Seventy-two symptomatic, medication-free subjects with bipolar I disorder (BD-I) and 76 healthy controls were evaluated using neuropsychological tests, and genotyped for COMT SNPs rs4680 and rs165599.

RESULTS

Patients undergoing mania and mixed episodes carrying the COMT allele G had better performance on executive function, memory, verbal fluency, and intelligence tests. Moreover, an interaction was detected between the COMT allele G and the Young Mania Rating Scale in BD CD.

CONCLUSIONS

Allele G from COMT SNPs rs4680 and rs165599 may represent reliable state-dependent predictors of global CD during manic and mixed episodes in BD. Further studies in larger samples are necessary to confirm these findings.

Affective symptoms and intra-individual variability in the short-term course of cognitive functioning in bipolar disorder

BACKGROUND

Few studies have examined the short-term course of cognitive impairments in bipolar disorder (BD). Key questions are whether trajectories in symptoms covary with cognitive function and whether BD is associated with increased intra-individual variability in cognitive abilities.

METHOD

Forty-two out-patients with BD and 49 normal comparison (NC) subjects were administered a battery of neuropsychological tests at baseline, 6, 12 and 26 weeks, along with concurrent ratings of depressive and manic symptom severity. Mixed-effects regressions were used to model relationships between time, diagnosis and symptom severity on composite cognitive performance. Within-person variance in cognitive functioning across time was calculated for each subject.

RESULTS

BD patients had significantly worse performance in cognitive ability across time points, but both groups showed significant improvement in cognitive performance over repeated assessments (consistent with expected practice effects). BD was associated with significantly greater intra-individual variability in cognitive ability than NCs; within-person variation was negatively related to baseline cognitive ability in BD but not NC subjects. Changes in affective symptoms over time did not predict changes in cognitive ability.

CONCLUSIONS

Moderate changes in affective symptoms did not covary with cognitive ability in BD. The finding of elevated intra-individual variability in BD may reduce capacity to estimate trajectories of cognitive ability in observational and treatment studies.

Neuropsychological performance in bipolar I, bipolar II and unipolar depression patients: a longitudinal, naturalistic study

BACKGROUND

It has been suggested that cognitive deficits existed in mood disorders. Nevertheless, whether neuropsychological profiles differ three main subtypes of mood disorder (Bipolar I, Bipolar II and UP) remain understudied because most current studies include either mixed samples of bipolar I and bipolar II patients or mixed samples of different states of the illness. The main aim of the present study is to determine whether, or to some extent, specific cognitive domains could differentiate the main subtypes of mood disorders in the depressed and clinically remitted status.

METHOD

Three groups of bipolar I (n=92), bipolar II (n=131) and unipolar depression (UP) patients (n=293) were tested with a battery of neuropsychological tests both at baseline (during a depressive episode) and after 6 weeks of treatment, contrasting with 202 healthy controls on cognitive performance. The cognitive domains include processing speed, attention, memory, verbal fluency and executive function.

RESULTS

At the acute depressive state, the three patient groups (bipolar I, bipolar II and UP) showed cognitive dysfunction in processing speed, memory, verbal fluency and executive function but not in attention compared with controls. Post comparisons revealed that bipolar I depressed patients performed significantly worse in verbal fluency and executive function than bipolar II and UP depressed patients. No difference was found between bipolar II and UP depressed patients except for the visual memory. After 6 weeks of treatment, clinically remitted bipolar I and bipolar II patients only displayed cognitive impairment in processing speed and visual memory. Remitted UP patients showed cognitive impairment in executive function in addition to processing speed and visual memory. The three remitted patient groups scored similarly in processing speed and visual memory.

LIMITATION

Clinically remitted patients were just recovered from a major depressive episode after 6 weeks of treatment and in relatively unstable state.

CONCLUSION

Bipolar I, bipolar II and UP patients have a similar pattern of cognitive impairment during the state of acute depressive episode, but bipolar I patients experience greater impairment than bipolar II and UP patients. In clinical remission, both bipolar and UP patients show cognitive deficits in processing speed and visual memory, and executive dysfunction might be a status-maker for bipolar disorder, but a trait-marker for UP.

The cognitive genetics of neuropsychiatric disorders

Classification in psychiatry is heavily dependent on clinical symptoms and illness course. This ignores the critical role that cognitive problems play in neuropsychiatric disorders affecting different domains across the lifespan, from ADHD and autism to schizophrenia and Alzheimers disease. At this point, it is unclear whether cognitive mechanisms are specific to disorders, whether multiple processes can contribute to the same disorder, or whether aberrant neural processing can result in many different phenotypic outcomes. Understanding this would allow us to better grasp normal as well as pathological brain function. This could inform diagnostics based on understanding of neurophysiological processes and the consequent development of new therapeutics. Genetics, and the development of genomic research, offers real opportunities to understand the molecular mechanisms relevant to cognition. This chapter defines and describes the main cognitive phenotypes, which are investigated in psychiatric disorders. We review evidence for their heritability and early progress in the field using cytogenetic, linkage and candidate gene-based research methodologies. With high-throughput genomics it is now possible to explore novel common and rare risk variants for psychiatric disorders and their role in cognitive function at a genome-wide level. We review the results of early genomic studies and discuss the novel insights that they are starting to provide. Finally, we review the analysis of whole-genome DNA sequence data and the challenges that this will bring for cognitive genomics research.