Sustained attention deficit in bipolar disorder

Alterações neuropsicológicas no transtorno bipolar

OBJETIVO: Revisão sistemática dos estudos controlados publicados nos últimos 15 anos sobre alterações neuropsicológicas no transtorno bipolar. MÉTODO: Foi realizado um levantamento bibliográfico no Medline, Lilacs, PubMed e ISI, selecionando-se o período de 1990 a 2005. Os estudos foram organizados a partir da comparação entre a amostra selecionada (bipolar versus outra patologia versus controles saudáveis). Nós só incluímos estudos controlados e com uma amostra de pacientes maior que 10, totalizando 73 artigos, do quais 53 foram selecionados para esta revisão. RESULTADOS: Pacientes com transtorno bipolar apresentam dificuldades em vários domínios cognitivos, sendo que alguns persistem mesmo após remissão dos sintomas. Os déficits encontrados se localizaram basicamente nas funções executivas. Na comparação com pacientes portadores de esquizofrenia, os bipolares apresentam perfil de alterações cognitivas mais leves, o que aponta para diferenças em termos de prognóstico da doença e para anormalidades em circuitos neuroanatômicos específicos. Houve correlação positiva entre déficits cognitivos e número de episódios ou internações. As medicações utilizadas para estabilização do humor podem ter um impacto negativo na cognição. CONCLUSÕES: Os prejuízos são sugestivos de disfunção em circuitos fronto-estriatais específicos que podem, em parte, explicar as dificuldades na adaptação psicossocial destes pacientes. Estudos futuros devem avaliar a eficácia de programas de reabilitação neuropsicológica, os quais visam, por meio de treinos cognitivos, minimizar o impacto dos déficits encontrados na vida diária dos pacientes.

Sustained attention deficits in manic and euthymic patients with bipolar disorder

Sustained attention deficits are proposed to be both state and trait indicators of bipolar disorder. The nature of these deficits and their association with medication and symptoms is not clear yet. The aim of this study was to investigate the impairments in various components of sustained attention task in euthymic and manic patients and was to investigate the relationship between the deficits in the manic state and medication effects. The performances of 37 manic patients, 34 euthymic patients with bipolar disorder and 34 control subjects on eight scores from Conners' CPT II, reflecting three different dimensions of sustained attention were compared. Similar to some recent findings, euthymic patients had decreased target sensitivity (omission errors) and response time inconsistency. The increased false responding (commission errors), perseveration and vigilance deficits were prominent in the manic patients. These state dependent impairments could not be explained by the impact of medication. In contrast, the exacerbation of seemingly trait-related impairments in the manic state can be at least partly explained by the impact of pharmacological therapy.

Toward constructing an endophenotype strategy for bipolar disorders

Research aimed at elucidating the underlying neurobiology and genetics of bipolar disorder, and factors associated with treatment response, have been limited by a heterogeneous clinical phenotype and lack of knowledge about its underlying diathesis. We used a survey of clinical, epidemiological, neurobiological, and genetic studies to select and evaluate candidate endophenotypes for bipolar disorder. Numerous findings regarding brain function, brain structure, and response to pharmacological challenge in bipolar patients and their relatives deserve further investigation. Candidate brain function endophenotypes include attention deficits, deficits in verbal learning and memory, cognitive deficits after tryptophan depletion, circadian rhythm instability, and dysmodulation of motivation and reward. We selected reduced anterior cingulate volume and early-onset white matter abnormalities as candidate brain structure endophenotypes. Symptom provocation endophenotypes might be based on bipolar patients' sensitivity to sleep deprivation, psychostimulants, and cholinergic drugs. Phenotypic heterogeneity is a major impediment to the elucidation of the neurobiology and genetics of bipolar disorder. We present a strategy constructed to improve the phenotypic definition of bipolar disorder by elucidating candidate endophenotypes. Studies to evaluate candidate endophenotypes with respect to specificity, heritability, temporal stability, and prevalence in unaffected relatives are encouraged.

A meta-analysis of cognitive deficits in euthymic patients with bipolar disorder

BACKGROUND

A number of studies have reported evidence of cognitive deficits in euthymic bipolar patients. Qualitative reviews of the literature have indicated impairments in executive functions and declarative memory are most consistently reported. However, not all primary studies conducted to date have had sufficient power to detect statistically significant differences and there have been few attempts to quantify the magnitude of impairments. This review aims to combine data from available studies to identify the profile of neuropsychological deficits in euthymic bipolar patients and quantify their magnitude.

METHOD

Systematic literature review and meta-analysis.

RESULTS

Large effect sizes (d>or=0.8) were noted for aspects of executive function (category fluency, mental manipulation) and verbal learning. Medium effect sizes (0.5<or=d<0.8) were found for aspects of immediate and delayed verbal memory, abstraction and set-shifting, sustained attention, response inhibition, and psychomotor speed. Small effect sizes (0.2<or=d<0.5) were reported for verbal fluency by letter, immediate memory, and sustained attention.

LIMITATIONS

Sufficient data were not available to investigate all domains. For example analyses did not include measures of visuospatial function.

CONCLUSION

Euthymic bipolar patients demonstrate relatively marked impairment in aspects of executive function and verbal memory. It is not yet clear whether these are two discrete areas of impairment or are related to one another. Future investigations should clarify the functional significance of deficits and indicate whether patients will benefit from ameliorative interventions.

Comparison of cognitive functions between first- and multi-episode bipolar affective disorders

BACKGROUND

Cognitive impairment has been commonly found in euthymic patients with bipolar affective disorder (BPAD). Information about onset and course of cognitive deficits is, however, scarce. This study examined the cognitive profile of patients following their first episode of BPAD to determine whether cognitive problems are present at such an early stage.

METHODS

Executive functions, memory, IQ, attention-concentration and perceptuomotor function were assessed in 16 euthymic patients with BPAD following their first episodes, and compared with a group of 30 euthymic patients with multiple episodes of BPAD and 20 normal controls. Comparisons were controlled for educational status, current IQ and residual symptoms.

RESULTS

First-episode patients were significantly impaired, compared to normal controls, on tests of executive function, sustained attention, perceptuomotor function and IQ. Additionally, their performance was significantly worse than patients with multi-episode BPAD on tests of executive functions, sustained attention and perceptuomotor function. Multi-episode patients had impaired memory, compared to normal controls, and performed poorly on a subtest of executive functions compared to first-episode patients.

LIMITATIONS

Sample sizes were small, assessments cross-sectional; all confounds could not be controlled for.

CONCLUSIONS

Widespread cognitive disturbances following the first episode of BPAD were found in this study. Whether these disturbances progress following repeated episodes was not entirely clear. Since cognitive impairment can have several adverse consequences for patients of BPAD in terms of disability, quality of life, outcome etc., this must remain a priority area for future research.

Patterns of memory impairment in bipolar disorder and unipolar major depression

Unipolar and bipolar depression are known to exert detrimental effects on learning and memory processes. However, few comparisons have been undertaken between bipolar and unipolar patients with comparable illness histories, and predictors of impairment are not well understood. Adult outpatients with unipolar major depressive illness (UP, n = 30) and bipolar disorder (BP, n = 30), group-matched for illness duration and severity of depressive symptomatology (16% clinically remitted, 42% partially remitted, 42% depressed), and 30 demographically matched controls completed measures of general cognitive functioning and declarative memory. Despite comparable general intellectual abilities, BP and UP patients exhibited significant memory deficits relative to healthy controls. A similar deficit profile was observed in both patient groups, involving poorer verbal recall and recognition. Impairments were not secondary to strategic processing deficits or rapid forgetting. Although depression severity was not associated with neurocognitive performance, number of hospitalizations and family history of mood disorder significantly affected memory function in BP, but not UP, patients. Results suggest qualitatively similar patterns of memory impairment in BP and UP patients, consistent with a primary encoding deficit. These impairments do not appear to be secondary to clinical state, but rather suggest a similar underlying pathophysiology involving medial temporal dysfunction.

Neural mechanisms of the cognitive control of emotion

BACKGROUND

Emotion regulation involves the initiation of new emotional responses and continual alteration of current emotions in response to rapidly changing environmental and social stimuli. The capacity to effectively implement emotion regulation strategies is essential for psychological health; impairments in the ability to regulate emotions may be critical to the development of clinical levels of depression, anxiety and mania.

OBJECTIVE

This review provides a summary of findings from current research examining the neural mechanisms of emotion regulation by means of conscious cognitive strategies of reappraisal. These findings are considered in the context of related concepts of emotion perception and emotion generation, with discussion of the likely cognitive neuropsychological contributions to emotion regulation and the implications for psychiatric disorders.

RESULTS

Convergent evidence implicates an inhibitory role of prefrontal cortex and cingulate regions upon subcortical and cortical emotion generation systems in the cognitive control of emotional experience. Concurrent modulation of cortical activity by the peripheral nervous system is highlighted by recent studies using simultaneous physiological and neuroimaging techniques. Individual differences in emotion perception, generation of affect and neuropsychological skills are likely to have direct consequences for emotion regulation.

CONCLUSIONS

Emotion regulation relies on synergy within brain stem, limbic and cortical processes that promote the adaptive perception, generation and regulation of affect. Aberrant emotion processing in any of these stages may disrupt this self-sustaining regulatory system, with the potential to manifest in distinct forms of emotion dysregulation as seen in major psychiatric disorders such as depression, bipolar disorder and schizophrenia.

The neural basis of mood dysregulation in bipolar disorder

Bipolar disorder is characterised by affective instability and mood dysregulation. Understanding of the neural mechanism underlying this remains limited, however. Here, findings will be described from studies that have employed neuroimaging techniques to measure neural responses to emotionally salient stimuli in individuals with the disorder. These findings will be discussed in relation to a theoretical framework previously proposed for understanding the separate cognitive processes underlying emotion perception to allow the formulation of a postulated neural mechanism for the mood dysregulation in bipolar disorder.

Cognitive impairment in bipolar disorder in old age: literature review and findings in manic patients

BACKGROUND

Descriptions of aged patients with bipolar (BP) disorder have commented on cognitive impairments. However, the literature regarding cognitive test performance in this population has apparently been scant.

METHOD

1. We reviewed studies reporting cognitive performance in aged BP patients. 2. We compared the performance of elderly BP manic patients and aged community comparison subjects on the Mini-Mental State Examination (MMSE) and the Mattis Dementia Rating Scale (DRS).

RESULTS

1. Seven published studies of cognitive measures in aged BP patients were identified. They utilized different assessment methods and addressed different illness states, but they indicate impairments in these patients. 2. In our sample, the manic patients (n=70) had lower MMSE scores and DRS scores than did the comparison subjects (n=37). In these patients, cognitive scores were not significantly associated with Mania Rating Scale scores.

LIMITATIONS

The patients in our study were assessed cross-sectionally, and they were treated naturalistically.

CONCLUSIONS

Manic or depressed BP elders have impaired cognitive function; in some patients these impairments may persist. Research characterizing these impairments and their clinical implications is warranted.

Functional imaging of mood and anxiety disorders

Neuroimaging research has emerged as a valuable tool in shaping our understanding of the pathophysiology of psychiatric disorders. We review functional neuroimaging findings pertaining to mood disorders (major depression, bipolar disorders) as well as selected anxiety disorders (posttraumatic stress disorder [PTSD] and obsessive-compulsive disorder [OCD]).

Evolution of cognitive impairment in bipolar disorder: a systematic review of cross-sectional evidence

OBJECTIVES

The notion that sufferers of bipolar disorder achieve complete syndromal and functional recovery between illness episodes has been brought into question by evidence that a large proportion of patients fail to regain premorbid levels of functioning after the resolution of major affective symptoms. A growing body of evidence suggests that bipolar patients exhibit neuropsychological impairment that persists even during the euthymic state, which may be a contributory factor to poor psychosocial outcome. However, the aetiology of such impairment and its relation to progression of illness are not well understood. This review aims to consider evidence from studies investigating both the relationship between cognitive impairment and clinical outcome and studies of neurocognitive function in unaffected first-degree relatives (FDRs) of bipolar sufferers to address issues of the temporal evolution of cognitive impairment in bipolar disorder.

METHODS

Systematic literature review.

RESULTS

The weight of evidence suggests that greater neuropsychological dysfunction in bipolar disorder is associated with a worse prior course of illness, particularly the number of manic episodes, hospitalizations and length of illness. The most consistent finding was a negative relationship between the number of manic episodes and verbal declarative memory performance. Impairment in unaffected FDRs was reported in verbal declarative memory and some facets of executive function.

CONCLUSIONS

Cognitive impairment may be a trait vulnerability factor for bipolar disorder that is present before illness onset and worsens as the illness progresses. Further investigation into the causal relationship between cognitive impairment and illness course is essential.

Neuropsychological dysfunction, soft neurological signs and social disability in euthymic patients with bipolar disorder

BACKGROUND

Neurocognitive deficits exist in euthymic patients with bipolar disorder, but relationships between symptoms, psychosocial and neurological factors remain uncertain.

AIMS

To measure neurocognitive function in bipolar disorder and explore links to sub-syndromal mood symptoms, soft neurological signs and psychosocial impairment.

METHOD

Attention, memory and executive function were tested in 37 euthymic patients with bipolar disorder and 37 controls. Psychosocial functioning, soft neurological signs and residual mood symptoms were assessed.

RESULTS

Performances on tests reflecting executive function and verbal memory (but not attention) were significantly poorer in the bipolar disorder group. Sub-syndromal mood symptoms produced small cognitive effects, predominantly on verbal memory. Soft neurological signs, especially frontal signs, were marked; some patients showed marked social disability which correlated strongly with soft neurological signs but weakly with executive dysfunction, which was linked to illness episodes.

CONCLUSIONS

Cognitive dysfunction, social dysfunction and soft signs occur in euthymic patients with bipolar disorder and may represent trait deficits.

Neuropsychological impairment in bipolar disorder: the relationship with glucocorticoid receptor function

OBJECTIVE

Basal levels of glucocorticoids, such as cortisol, are generally unaltered in bipolar disorder. However, neuroendocrine tests of glucocorticoid receptor (GR) function such as the dexamethasone suppression test (DST) are frequently abnormal. Neuropsychological impairment is well documented in healthy volunteers after administration of glucocorticoids and in patients with bipolar affective disorder. This suggests a potential link between neuropsychological and hypothalamic-pituitary-adrenal axis function. We examined the hypothesis that neuropsychological impairment in bipolar disorder is associated with abnormal GR function.

METHODS

Seventeen euthymic bipolar patients and 16 controls completed tests of verbal declarative and working memory (WM) tests and the DST. The correlation between neuroendocrine and neuropsychological function was examined.

RESULTS

Bipolar patients made significantly more errors of omission and commission on the WM paradigm and demonstrated impaired verbal recognition memory. Patients' post-dexamethasone cortisol correlated with WM commission errors (r(s) = 0.64, p = 0.0006). No such relationship was evident in controls.

CONCLUSION

Deficits in declarative memory and WM are evident in patients with bipolar disorder. The deficit in retrieval accuracy from WM appears to be correlated with abnormal GR function.

Neurocognitive impairment in euthymic young adults with bipolar spectrum disorder and recurrent major depressive disorder

OBJECTIVE

Patients with remitted major depressive disorder (MDD) and bipolar disorder have persistent impairments in executive function and verbal memory that may represent endophenotypic abnormalities. In this study, we examine neurocognitive function in a sample of euthymic young adults with bipolar spectrum disorder (BSD) (Can J Psychiatry 2002; 47: 125-134) and compare this to well-matched samples of young adults with recurrent MDD and controls.

METHOD

Twenty-one euthymic young adult patients with BSD were compared with 42 young adult patients with MDD and 33 controls on a neuropsychological battery assessing attention, executive function and verbal memory.

RESULTS

Patients with BSD were significantly more impaired than MDD patients and controls on tests of executive function and verbal memory. MDD patients did not differ significantly from controls on verbal memory function but performed less well on a test of executive function.

CONCLUSION

Euthymic young adults with BSD had greater impairment on neurocognitive measures associated with prefrontal and hippocampal function than MDD patients and controls. This is a reflection of a strong bipolar diathesis in the BSD group rather than being a consequence of a more severe unipolar illness.

Sources of declarative memory impairment in bipolar disorder: mnemonic processes and clinical features

BACKGROUND

There is mounting evidence that declarative memory processes are impaired in patients with bipolar disorder. However, predictors of the observed impairment are not well understood. This study seeks to: (i) better characterize the nature of declarative memory impairment in bipolar disorder, and (ii) determine the relationship between clinical variables and memory function in bipolar disorder.

METHODS

49 adult patients with bipolar disorder in varying mood states and 38 demographically matched healthy participants completed a comprehensive neurocognitive battery assessing general cognitive functioning, processing speed, and declarative memory. The California verbal learning test was used to characterize learning and memory functions.

RESULTS

Although patients with bipolar disorder utilized a similar semantic clustering strategy to healthy controls, they recalled and recognized significantly fewer words than controls, suggesting impaired encoding of verbal information. In contrast, lack of rapid forgetting suggests relative absence of a storage deficit in bipolar patients. While severity of mood symptomatology and illness duration were not associated with task performance, gender and family history significantly affected memory function.

CONCLUSIONS

Results suggest that declarative memory impairments in bipolar patients: (1) are consistent with deficits in learning, but do not appear to be related to different organizational strategies during learning, and (2) do not appear to be secondary to clinical state, but rather may be associated with the underlying pathophysiology of the illness.

Impaired recruitment of the dorsolateral prefrontal cortex and hippocampus during encoding in bipolar disorder

BACKGROUND

The aim of the present study was to examine the functional neuroanatomy of episodic memory impairment in euthymic subjects with bipolar I disorder. There is evidence that individuals with bipolar disorder have cognitive impairments not only during mood episodes but also when they are euthymic. The most consistently reported cognitive difficulty in euthymic subjects with bipolar disorder is impairment in verbal episodic memory (i.e., the ability to learn new verbal information).

METHODS

The current study examined verbal learning in eight euthymic, remitted subjects with bipolar I disorder (BP-I; seven nonmedicated) and eight control subjects matched for age, gender, education, and intelligence. Subjects underwent (15)O-CO(2) positron emission tomography scanning while completing a verbal learning paradigm that consisted of encoding (learning) several lists of words.

RESULTS

The BP-I subjects had more difficulties learning the lists of words compared with the control subjects. Compared with control subjects, BP-I subjects exhibited blunted regional cerebral blood flow (rCBF) increases in the left dorsolateral prefrontal cortex (Brodmann's area 9/46) during encoding.

CONCLUSIONS

Consistent with previous studies, subjects with BP-I were impaired in learning new verbal information. This was associated with rCBF abnormalities in brain regions involved in learning and episodic memory.

Cognitive deficits in psychiatric disorders: Current status

Cognition denotes a relatively high level of processing of specific information including thinking, memory, perception, motivation, skilled movements and language. Cognitive psychology has become an important discipline in the research of a number of psychiatric disorders, ranging from severe psychotic illness such as schizophrenia to relatively benign, yet significantly disabling, non-psychotic illnesses such as somatoform disorder. Research in the area of neurocognition has started unlocking various secrets of psychiatric disorders, such as revealing the biological underpinnings, explaining the underlying psychopathology and issues related to course, outcome and treatment strategies. Such research has also attempted to uproot a number of previously held concepts, such as Kraepelin's dichotomy. Although the range of cognitive problems can be diverse, there are several cognitive domains, including executive function, attention and information processing, and working memory, which appear more frequently at risk. A broad range of impairment across and within the psychiatric disorders are highlighted in this oration. The oration summarizes the studies investigating cognitive processing in different psychiatric disorders. I will also discuss the findings of my own research on neurocognitive deficits in mood disorders, schizophrenia, obsessive-compulsive disorder, somatoform disorder, including studies on 'high-risk' individuals. Tracing the evaluation of neurocognitive science may provide new insights into the pathophysiology and treatment of psychiatric disorders.

Spatial working memory function in twins with schizophrenia and bipolar disorder

BACKGROUND

Family studies are in conflict as to whether schizophrenia and bipolar disorder have independent genetic etiologies. Given the relatively low prevalence (approximately 1%) of these disorders, the use of quantitative endophenotypic markers of genetic liability might provide a more sensitive strategy for evaluating their genetic overlap. We have previously demonstrated that spatial working memory deficits increase in a dose-dependent fashion with increasing genetic proximity to a proband among the unaffected co-twins of schizophrenic patients. Here, we evaluated whether such deficits might also mark genetic susceptibility to bipolar disorder.

METHODS

The Wechsler Memory Scale-Revised Visual Memory Span and Digit Span subtests were administered to 46 schizophrenic patients, 32 of their unaffected co-twins, 22 bipolar patients, 16 of their unaffected co-twins, and 100 control twins, representing unselectively nationwide twin samples.

RESULTS

Schizophrenic patients and their unaffected co-twins performed significantly worse than control subjects on the spatial working memory task, whereas only the schizophrenic patients performed significantly below the control subjects on the verbal working memory task. Neither bipolar patients nor their unaffected co-twins differed from control subjects on these measures.

CONCLUSIONS

Our findings support the hypothesis that impairment in spatial working memory might effectively reflect an expression of genetic liability to schizophrenia but less clearly to bipolar disorder.

The Maudsley Bipolar Disorder Project: executive dysfunction in bipolar disorder I and its clinical correlates

BACKGROUND

Cognitive abnormalities are increasingly recognized as a feature of bipolar I disorder (BDI,) but there is limited information regarding the pattern and severity of cognitive impairment during remission and its relationship with clinical variables.

METHODS

Forty-four remitted BDI patients recruited from a representative treatment sample and an equal number of matched healthy volunteers underwent comprehensive clinical and cognitive assessments. Cognitive evaluation covered the domains of IQ, memory, and executive function. The profile of cognitive deficits in patients was examined, and the correlation of executive function with clinical features and treatment variables was explored.

RESULTS

Remitted BDI patients were impaired in tests of executive function compared with healthy participants. Within the patient group, current antipsychotic treatment predicted worse performance across all executive function tests, whereas duration of illness predicted loss of inhibitory control. Residual mood symptoms, regardless of polarity, had a negative impact primarily on measures of attentional interference.

CONCLUSIONS

These results suggest that impaired executive function might be an important feature of BDI. Antipsychotic treatment, duration of illness, and level of symptoms are the most significant contributors to the observed impairment.

Maudsley Bipolar Disorder Project: insights sobre o papel do córtex pré-frontal em pacientes com transtorno de humor bipolar tipo I

OBJETIVO: O projeto Maudsley Bipolar Disorder foi criado para investigar características cognitivas e estruturais/funcionais do cérebro em pacientes com Transtorno de Humor Bipolar Tipo I (THB-I). MÉTODOS: Quarenta e três pacientes com THB-I foram selecionados em uma unidade de atendimento secundário, em um momento de remissão da doença, para participarem do estudo. Os pacientes foram pareados a controles sadios de acordo com idade, sexo, raça e nível de escolaridade. Cada participante foi submetido a uma extensa revisão clínica, com avaliação cognitiva e exame de ressonância magnética (RM) para a obtenção de dados estruturais e funcionais do cérebro. RESULTADOS: Quando comparados aos controles, os pacientes demonstraram um sutil e difuso comprometimento com redução mais marcante no nível das funções executivas. Os pacientes também apresentaram decrementos volumétricos no córtex pré-frontal ventral (CPFV) bilateralmente e córtex pré-frontal dorsal (CPFD) esquerdo. O volume da amígdala estava bilateralmente aumentado. A ressonância magnética funcional (RMf) mostrou anormalidades sutis no CPFD, com marcados decrementos de atividade tanto no CPFD como no CPFV durante tarefas que dependiam da interação funcional dessas regiões. CONCLUSÕES: Os resultados sugerem que ocorrem traços de déficits em funções executivas em pacientes com THB-I, assim como alteração de estrutura e funcionamento do córtex pré-frontal.

Blunted activation in orbitofrontal cortex during mania: a functional magnetic resonance imaging study

BACKGROUND

Patients with bipolar disorder have been reported to have abnormal cortical function during mania. In this study, we sought to investigate neural activity in the frontal lobe during mania, using functional magnetic resonance imaging (fMRI). Specifically, we sought to evaluate activation in the lateral orbitofrontal cortex, a brain region that is normally activated during activities that require response inhibition.

METHODS

Eleven manic subjects and 13 control subjects underwent fMRI while performing the Go-NoGo task, a neuropsychological paradigm known to activate the orbitofrontal cortex in normal subjects. Patterns of whole-brain activation during fMRI scanning were determined with statistical parametric mapping. Contrasts were made for each subject for the NoGo minus Go conditions. Contrasts were used in a second-level analysis with subject as a random factor.

RESULTS

Functional MRI data revealed robust activation of the right orbitofrontal cortex (Brodmann's area [BA] 47) in control subjects but not in manic subjects. Random-effects analyses demonstrated significantly less magnitude in signal intensity in the right lateral orbitofrontal cortex (BA 47), right hippocampus, and left cingulate (BA 24) in manic compared with control subjects.

CONCLUSIONS

Mania is associated with a significant attenuation of task-related activation of right lateral orbitofrontal function. This lack of activation of a brain region that is usually involved in suppression of responses might account for some of the disinhibition seen in mania. In addition, hippocampal and cingulate activation seem to be decreased. The relationship between this reduced function and the symptoms of mania remain to be further explored.

No evidence for verbal memory impairment in individuals putatively at risk for bipolar disorder

BACKGROUND

Hypomanic temperament and rigid personality are putative risk factors for affective episodes and even bipolar disorder. Individuals with bipolar disorder exhibit neuropsychological impairments, especially memory difficulties, not only during mood episodes but also when they are euthymic. Such cognitive impairments may also constitute a risk factor for bipolar disorder. The purpose of the present study was to investigate the presence of memory difficulties in individuals with hypomanic and rigid personality traits.

METHODS

Study participants were 6000 German students recruited from high schools, colleges, and vocational schools in Germany. The students completed the Hypomanic Personality Scale and the Rigidity subscale of the Munich Personality Test. Four groups of students were selected from this sample based on their scores in the Hypomanic Personality Scale and Rigidity subscale: individuals with (1) hypomanic temperament, (2) rigid temperament, or (3) hypomanic-rigid temperament and (4) control participants. These students (n = 153) completed the Rey-Auditory Verbal Learning Test, a well-established measure of verbal learning and memory, as well an IQ test (Leistungsprüfsystem).

RESULTS

Multiple regression analyses indicated that sex and IQ, but not temperament, predicted learning of the Auditory Verbal Learning Test word list, the number of words recalled at short-delayed recall, and recognition.

LIMITATIONS

The risk for affective disorders was only defined by psychometric measures, and we did not control for family history of bipolar disorders.

CONCLUSIONS

Hypomanic temperament and Rigid personality were not associated with verbal learning and memory. Cognitive impairment may be associated with repeated mood episodes rather than constituting a risk factor for bipolar disorder.

Cognitive style in bipolar disorder

BACKGROUND

Abnormalities of cognitive style in bipolar disorder are of both clinical and theoretical importance.

AIMS

To compare cognitive style in people with affective disorders and in healthy controls.

METHOD

Self-rated questionnaires were administered to 118 individuals with bipolar I disorder, 265 with unipolar major recurrent depression and 268 healthy controls. Those with affective disorder were also interviewed using the Schedules for Clinical Assessment in Neuropsychiatry and case notes were reviewed.

RESULTS

Those with bipolar disorder and those with unipolar depression demonstrated different patterns of cognitive style from controls; negative self-esteem best discriminated between those with affective disorders and controls; measures of cognitive style were substantially affected by current levels of depressive symptomatology; patterns of cognitive style were similar in bipolar and unipolar disorder when current mental state was taken into account.

CONCLUSIONS

Those with affective disorder significantly differed from controls on measures of cognitive style but there were no differences between unipolar and bipolar disorders when current mental state was taken into account.

Deficits in sustained attention in schizophrenia but not in bipolar disorder

The aim of the present study was to investigate sustained attention in remitted patients with bipolar disorder and in patients with schizophrenia, as compared to each other and to healthy controls; a secondary aim was to investigate the correlations of different symptom dimensions with performance on sustained attention in the two patient groups. Participants were 29 (18 men) outpatients with schizophrenia (SZ), 19 (8 men) patients with bipolar disorder I (BP) in remission, and 30 (15 men) healthy controls (HC); all three groups were matched on age, sex ratio, and level of education. Symptom severity (positive symptoms, negative symptoms, and general psychopathology) of patients with SZ were assessed with the Greek version of the Positive and Negative Syndrome Scale (PANSS); residual affective symptoms of patients with BP were assessed with the Young Mania Rating Scale (YMRS) and the Montgomery-Asberg Depression Rating Scale (MADRS). Sustained attention was measured by means of the Penn Continuous Performance Test (PCPT). The three groups differed significantly on the PCPT scores. Patients with SZ performed more poorly than both the BP and HC groups, whereas patients with BP did not differ significantly from HC. Performance on the PCPT did not correlate significantly with scores on the YMRS and MADRS in patients with BP. Also, scores on the PCPT did not correlate significantly with scores on any of the three subscales of the PANSS. Outpatients with schizophrenia presented deficits in sustained attention, whereas patients with bipolar disorder I in remission did not manifest such impairment. These results imply that impaired sustained attention might be a more enduring deficit in schizophrenia than it appears to be in bipolar disorder.

Neuropsychological functioning in youth with bipolar disorder

BACKGROUND

Little is known about the neuropsychological status of youth with bipolar disorder (BPD) or whether cognitive deficits in this population are accounted for by comorbidity with attention deficit/hyperactivity disorder (ADHD). We compared neuropsychological and academic functioning of youth with and without DSM-IV BPD, controlling for effects of comorbid ADHD.

METHODS

Fifty-seven youth with BPD and 46 healthy control subjects were assessed on a battery of clinical neuropsychological measures including subtests from the Wechsler Intelligence Scales for Children and Adults (Third Editions), the Stroop, the Wisconsin Card Sorting Test, the Rey-Osterreith Complex Figure, an auditory working memory Continuous Performance Test, a measure of verbal learning, and the Wide Range Achievement Test-Third Edition.

RESULTS

Bipolar disorder was associated with impairments on subtests reflecting sustained attention, working memory, and processing speed after controlling for ADHD. Additionally, decrements of moderate effect sizes were found for measures of interference control, abstract problem solving, and verbal learning but did not meet criteria for statistical significance.

CONCLUSIONS

After controlling for ADHD, youth with BPD show neuropsychological deficits similar to impairments found in adults with the disorder. Further studies are needed to understand the clinical implications of these impairments as well as their role in the underlying risk for pediatric BPD.

Fronto-limbic brain abnormalities in juvenile onset bipolar disorder

BACKGROUND

Advances in brain imaging techniques and cognitive neuropsychology have brought new possibilities for the in vivo study of the pathophysiology of neuropsychiatric disorders, including bipolar disorder (BD). Recently, such studies have been extended to the pediatric age range. Here we review the neuroimaging and neuropsychological studies conducted in BD children and adolescents.

METHODS

A review of the peer-reviewed published literature was conducted in Medline for the period of 1966 to April 2005.

RESULTS

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies suggest abnormalities in fronto-limbic structures in pediatric BD patients, similar to those found in adults. A notable exception in pediatric BD patients is smaller amygdala volumes compared to healthy controls, contrary to what has been reported in most adult studies.

CONCLUSIONS

Further research evaluating children and adolescents is needed to study the normal neurodevelopmental process and to answer how and when the illness processes that result in bipolar disorder exert their effects on the developing brain.

High homocysteine serum levels in young male schizophrenia and bipolar patients and in an animal model

Elevated plasma homocysteine has been found to be a risk factor for Alzheimer's disease as well as cerebral vascular disease, suggesting that some risk factors can accelerate or increase the severity of several CNS disease processes. We screened plasma total homocysteine levels of 193 schizophrenic patients vs. 762 controls for plasma homocysteine levels. The effect of schizophrenia was marked (p<0.0001) and mean homocysteine level was 16.3+/-12 (S.D.) microM in schizophrenic patients vs. 10.6+/-3.6 (S.D.) microM in healthy controls. The increase was almost entirely in young male schizophrenic patients. It seemed important to determine if this finding is already present in newly admitted schizophrenic patients. Serum homocysteine levels were studied in 184 consecutively admitted schizophrenic patients and 305 control subjects. Homocysteine levels were markedly increased in this population of newly admitted schizophrenic patients, especially in young males. However, no difference was found for CSF homocysteine levels between schizophrenia patients and controls. We also examined homocysteine levels in 41 euthymic outpatients with bipolar disorder. Functional deterioration in patients was rated as 'present' or 'absent' by consensus of two treating clinicians. Young male bipolar patients were found to have higher homocysteine levels than controls. Among the male subjects, bipolar patients showing deterioration had homocysteine levels which were significantly higher than other patients. We attempted to develop a model of homocysteine neurotoxicity in mice. Mice were fed homocysteine in water at a dose of 200 mg/kg per mouse per day. Independent samples of animals were studied at 2 to 6 months with behavioral tests including apomorphine-induced stereotypy and spatial learning and memory in the Morris Water Maze. Homocysteine levels were elevated up to 800% at months 5 and 6 by this procedure. No homocysteine-induced defects were found in any behavioral test until month 5 when mild but statistically significant abnormalities in the Morris Water Maze were detected.

The phenotypes of bipolar disorder: relevance for genetic investigations

The search for susceptibility genes for bipolar disorder (BD) depends on appropriate definitions of the phenotype. In this paper, we review data on diagnosis and clinical features of BD that could be used in genetic studies to better characterize patients or to define homogeneous subgroups. Clinical symptoms, long-term course, comorbid conditions, and response to prophylactic treatment may define groups associated with more or less specific loci. One such group is characterized by symptoms of psychosis and linkage to 13q and 22q. A second group includes mainly bipolar II patients with comorbid panic disorder, rapid mood switching, and evidence of chromosome 18 linkage. A third group comprises typical BD with an episodic course and favourable response to lithium prophylaxis. Reproducibility of cognitive deficits across studies raises the possibility of using cognitive profiles as endophenotypes of BD, with deficits in verbal explicit memory and executive function commonly reported. Brain imaging provides a more ambiguous data set consistent with heterogeneity of the illness.

Evidence for theory of mind deficits in euthymic patients with bipolar disorder

OBJECTIVE

i) To investigate the subtle ToM (theory of mind) deficits in euthymic patients with bipolar disorder. ii) To investigate the impact of non-ToM cognitive deficits on ToM abilities.

METHOD

Forty-three euthymic patients with bipolar disorder and 30 healthy control subjects were involved in this study. ToM was assessed by the Eyes test and the Hinting task. Both groups were also evaluated with a comprehensive neuropsychological battery including tasks for basic emotion and face recognition.

RESULTS

The patient group was impaired on both of the ToM tasks. The patient group also showed impairment in many cognitive tasks including tasks related to sustained attention.

CONCLUSION

Even euthymic patients with bipolar disorder may be impaired in advanced ToM tasks. Executive dysfunction and some other cognitives deficits such as basic emotion recognition may be at least partly responsible for this result.

The Maudsley Bipolar Disorder Project

PURPOSE

The Maudsley Bipolar Disorder Project set out to investigate the cognitive and brain structural and functional characteristics of Bipolar Disorder I (BDI).

METHODS

Participating patients were recruited while in remission from a secondary care setting and were matched to healthy volunteers in terms of age, gender, race, and years of education. All participants underwent extensive clinical and cognitive assessment. Brain structural and functional data also were obtained by using magnetic resonance imaging (MRI).

RESULTS

Compared with controls, patients showed subtle widespread decrements, with executive function being more markedly impaired. Patients also showed volume decrements in the ventral prefrontal cortex (VPFC) bilaterally and the dorsal PFC (DPFC) on the left, whereas the volume of the amygdala was bilaterally enlarged. Patients showed subtle abnormalities in functional MRI in their DPFC, with marked decrements in activity in both the DPFC and VPFC in tasks that rely on the functional interaction of these brain regions.

CONCLUSIONS

Our results suggest that BDI is associated with trait deficits in executive function and in the structure and function of the PFC.

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.

Cognition in bipolar disorder

BPD is often associated with cognitive deficits that tend to be present regardless of mood state. Greater impairments tend to be seen in BPD patients who are older, have an early onset of the disease, and suffer a more severe course of illness. The literature also suggests that cognitive deficits are present early in patients with BPD and may be cumulative, showing an association with the number of affective (particularly depressed) episodes over time. Cognitive deficits in BPD may share some common characteristics with those seen in patients with schizophrenia, although the latter tend to show much greater and generalized cognitive impairment. For example, unlike patients with schizophrenia, patients with BPD typically do not score lower than normal persons on measures of global intellectual ability. There also is not overwhelming evidence of laterality or localization of cognitive deficits in BPD, although debate in the literature continues. More visuospatial deficits tend to be found in BPD and UPD than in schizophrenia, thereby raising the possibility of greater involvement of right hemisphere systems in mood disorders. In general, despite variability across investigations, deficits in executive functioning, episodic memory,sustained concentration, and, to a lesser extent, visuospatial skills seem to be the most consistent areas of impairment in BPD. Just as neuroimaging anomalies have been well documented in schizophrenia, structural brain abnormalities have been noted in BPD,most commonly involving the basal ganglia or white matter. Specific comparisons of cerebral atrophy and ventricular size between patients with schizophrenia and BPD have not been definitive, making it difficult to draw conclusions about structural brain abnormalities that might be specific to BPD. Nonetheless, there is enough evidence to suggest that white-matter abnormalities are reported with a greater frequency in BPD patients than in patients with UPD or schizophrenia. Functional neuro-imaging studies of mood disorders have indicated that the frontal cortex,basal ganglia, and temporal lobes are involved. The relationships between neuroimaging and neurocognitive abnormalities in BPD are worthy of additional investigation. Clearly, efforts directed toward phenotyping neuropsychiatric disorders using such measures, in addition to other clinical, neuroimaging, neurophysiologic, and genotypic information, may yield important insights into the development, nature, and course of illness. It is hoped that this understanding will lead to better identification of individuals who may be prone to greater cognitive impairment or decline and those who might be more responsive to specific treatments.

When euthymia is just not good enough: the neuropsychology of bipolar disorder

Bipolar disorder (BD) is a debilitating psychiatric illness that is uniquely characterized by switching between psychopathologically contrasting phases of mania and depression, often with intervening periods of euthymia. However, these periods of apparent clinical recovery (euthymia) are marked by subtle social, occupational, and cognitive impairments, profiled by recent neuropsychological investigations. Determining the cognitive changes across these three phases may help differentiate the disruptions that are mood state-dependent from those associated with underlying pathology. This article therefore critically reviews the reported neuropsychological impairments in BD and the methodological limitations facing such research. Integration of the available evidence, principally from the field of neuropsychology, when synthesized, implicates the prefrontal cortex in the etiopathogenesis of BD and posits cortical-subcortical-limbic disruption in recovered euthymic patients that manifests as cognitive dysfunction.

Neuropsychological disturbances and cerebral blood flow in bipolar disorder

OBJECTIVE

To determine and correlate alterations in neuropsychological function and cerebral blood flow in bipolar patients.

METHOD

Assessments included the Positive and Negative Symptom Scale, Global Assessment Functioning, Wechsler Adult Intelligence Scale (WAIS), Wisconsin Card Sorting Test (WCST), Stroop test, Trail Making Test (TMT), California Verbal Learning Test (CVLT), Wechsler Memory Scale (WMS) and phonetic verbal fluency/controlled oral word association tests. Single photon emission computed tomography (SPECT) was carried out with the administration of 99mTc-HMPAO. Forty-three outpatients out of 85 fulfilling RDC diagnostic criteria for bipolar disorder and six healthy subjects were included in the study. SPECT and neuropsychological assessments were performed in 30 patients in manic (n = 7), hypomanic (n = 8), depressed (n = 12) or euthymic (n = 3) states. All assessments were carried out before starting treatment.

RESULT

Several corrected correlations between neuropsychological function and cerebral blood flow (CBF) were identified: executive function (WCST) and striatal, frontal, temporal, cerebellum, parietal and cingulate CBF; memory (WMS, WAIS-Digits) and striatal, frontal, temporal and parietal CBF; attentional tasks (Stroop) and striatal, temporo-medial and parietal CBF; verbal learning (CVLT) and frontal, posterior temporal, cingulate and occipital CBF; psychomotor disturbances (TMT) and anterior temporal CBF; poorer intelligence performance scores (WAIS-Vocabulary) and cerebellum and parietal CBF.

CONCLUSIONS

This study confirms the presence of functional disturbances in fronto-subcortical structures, the cerebellum and limbic system in bipolar patients.

Spontaneous and directed application of verbal learning strategies in bipolar disorder and obsessive-compulsive disorder

OBJECTIVES

Individuals with bipolar disorder exhibit neuropsychological impairments when they are euthymic (neither depressed nor manic). One of the most consistently reported cognitive problems in euthymic individuals with bipolar disorder is impairment in verbal episodic memory. Recent findings suggest that episodic memory difficulties in these individuals are attributable to difficulties using organizational strategies during encoding. The purpose of the present study was (i) to investigate whether difficulties using organizational strategies in bipolar disorder are due to a failure in spontaneously initiating verbal organization strategies or are due to difficulties implementing such strategies, and (ii) to compare the characteristics of verbal organizational impairment in bipolar disorder with those observed in individuals with obsessive-compulsive disorder (OCD).

METHODS

Study participants were 20 individuals with bipolar I disorder (BP-I), 20 individuals with OCD, and 20 healthy control participants matched for age, gender, and education. Participants completed a verbal encoding paradigm that involved spontaneous and directed use of verbal organization strategies during encoding of word lists.

RESULTS

Compared with control subjects, both BP-I and OCD participants showed impaired verbal organization in the spontaneous encoding condition. In the directed encoding condition, OCD patients organized the word lists as well as control participants whereas BP-I participants exhibited lower verbal organization than both control and OCD participants. OCD and BP-I participants' free recall performance did not differ from that of control participants in the spontaneous encoding condition. In the directed encoding condition, BP-I participants recalled fewer words than OCD or control participants.

CONCLUSIONS

Episodic memory difficulties in OCD are associated with difficulties spontaneously initiating verbal organization strategies during encoding whereas the ability to implement verbal organization when instructed to do so is preserved. BP-I participants, on the other hand, exhibit difficulties in both spontaneously initiating verbal organization strategies and in the ability to implement such strategies when instructed to do so.

The subjective and cognitive effects of acute phenylalanine and tyrosine depletion in patients recovered from depression

Although there is evidence for the involvement of dopamine (DA) in unipolar depression, no published study has yet used the technique of acute phenylalanine and tyrosine depletion (APTD), a dietary intervention that selectively lowers DA synthesis, in order to investigate the role of DA in mood disturbance. Tyrosine and phenylalanine depleted and placebo amino acid drinks were administered to 20 patients recovered from depression in a double-blind, placebo-controlled, crossover design. Measures included subjective effects, Hamilton Depression Rating Scale scores, and a comprehensive battery of well-validated computerized cognitive tests. APTD induced a substantial reduction in the ratio of plasma tyrosine and phenylalanine to large neutral amino acids. However, relapse of depressive symptoms was not seen. Although performance on most cognitive tests was unaffected, there was a selective effect on decision-making, with APTD causing participants to bet significantly less. In conclusion, These results suggest a specific role for the involvement of DA in reward/punishment processing in humans. While APTD did not induce relapse in any participant, it did cause patients recovered from depression to show lowered sensitivity to reward in a gambling game. It is hypothesized that tests involving reward/punishment processing are preferentially affected by DA depletion, and that a more complete account of depression is likely to result from considering the roles played by serotonin, noradrenaline, and DA in mediating the various cognitive and clinical symptoms, including anhedonia.

Working memory and inhibitory control among manic and euthymic patients with bipolar disorder

Bipolar disorder (BPD) is a severe psychiatric illness that is characterized by episodes of extreme mood states. The affective components of bipolar disorder have been studied extensively, but only recently have investigators begun to systematically examine its cognitive concomitants. Although executive dysfunction has been reported in this population, especially while patients are manic, the tasks administered in many previous studies have made it difficult to determine the specific executive abilities that were compromised. The present study examined 15 patients with bipolar disorder who were manic, 18 who were euthymic, and 18 healthy participants. Tests were selected to evaluate two specific aspects of executive functioning in these participants. The Object Alternation Task was given as a measure of inhibitory control, and the Delayed Response Task was included as a measure of spatial delayed working memory. All groups performed similarly on the Delayed Response Task. On the Object Alternation Task, however, the manic and euthymic patients committed significantly more perseverative errors than healthy participants. These results indicated that patients in the present sample had relatively normal working memory abilities, but had a deficit in behavioral self-regulation, which was evident across mood states.

Neuropsychological deficits in adolescents with conduct disorder and comorbid bipolar disorder: a pilot study

OBJECTIVE

We report pilot data on neuropsychological deficits in aggressive juvenile offenders with and without bipolar disorder compared with each other and healthy controls.

METHOD

We assessed 52 adolescents and their parent or guardians: 36 incarcerated juvenile offenders and 16 community controls using the Schedule for Affective Disorders and Schizophrenia for School Age Children, Present and Life-Time Version and a neuropsychological testing battery. All incarcerated subjects (n=34) met criteria for Conduct Disorder (CD); 26 are classified as Non-BD-CD, and eight with CD and Bipolar disorder (CD-BD). These subjects were compared to community controls (n=16) matched for age, gender, SES and ethnicity.

RESULTS

Relative to controls, the Non-BD-CD subjects' impairments (p<0.05) were in cognitive ability, set shifting/inhibition, planning and verbal memory-language functioning. The CD-BD group displayed impairments (p<0.05) relative to controls in cognitive ability, set shifting, verbal memory-language functioning, and visuospatial tasks. The Non-BD-CD and CD-BD groups however did not display significant differences on most neuropsychological measures compared with each other. When we controlled for Attention Deficit Hyperactivity Disorder, the Non-CD-BP subjects continued to show deficits on Verbal measures where the CD-BD subjects maintained deficits in measures of cognitive ability, verbal measures and visual spatial tests.

CONCLUSIONS

Juvenile offender with CD displayed a wide range of deficits on neuropsychological testing compared with controls. Although juvenile offenders with and without BD differed on their clinical presentation, differences on neuropsychological measures are not specific and may be related to comorbid diagnoses.

Attention deficits in bipolar disorder: a comparison based on the Continuous Performance Test

Although attentional deficits measured by Continuous Performance Tests (CPTs) have been observed in patients with bipolar disorder, their relationship with clinical state is not well understood. The identical pairs Continuous Performance Test (CPT-IP) shows particular promise as a measure sensitive to trait abnormalities in attentional function. In this study, the CPT-IP was administered to 27 patients with bipolar disorder (22 type I, 5 type II) and 25 demographically matched healthy comparison subjects, in order to assess the presence and nature of attentional deficits as a function of mood symptoms. Results showed significantly impaired CPT performance in bipolar patients compared with healthy subjects. Patients made fewer hits (p < 0.01), were slower to respond (p < 0.007), and had poorer discrimination (p < 0.05) and bias (p < 0.006) than comparison subjects. Severity of mania and depression was not correlated with any of the CPT measures. Our findings suggest that attentional dysfunction may be a trait deficit associated with bipolar illness. However, within-subjects longitudinal studies examining fluctuations in performance over time are needed.

Sustained attention-deficit confirmed in euthymic bipolar disorder but not in first-degree relatives of bipolar patients or euthymic unipolar depression

BACKGROUND

Cognitive dysfunction persists in the euthymic phase of bipolar disorder and may provide a marker of underlying neuropathology and disease vulnerability. This study aimed to replicate a deficit in sustained attention in euthymic bipolar patients and investigate sustained attention in first-degree relatives of bipolar probands and in remitted patients with major depressive disorder.

METHODS

The rapid visual information processing (RVIP) task was used to measure sustained attention in 15 euthymic patients with bipolar disorder and 15 control subjects in experiment 1 and in 27 first-degree relatives of bipolar probands, 15 remitted patients with major depressive disorder, and 46 control subjects in experiment 2.

RESULTS

Sustained attention deficit was confirmed in the euthymic bipolar patients in experiment 1, but the deficit was not statistically significant in remitted major depressed patients or in the relatives of bipolar probands.

CONCLUSIONS

A deficit of sustained attention is not present in patients with recurrent major depression tested during remission nor is it discriminable in the first-degree relatives of bipolar probands. Thus, the confirmed abnormality in euthymic bipolar patients may be acquired as a consequence of bipolar illness. However, future studies of relatives will require larger sample sizes to exclude or utilize small genetic effects.

Neuropsychological profile of patients with bipolar depression in remission

Aim. To determine if the patients with bipolar affective disorder, after the depressive phase, would exhibit cognitive impairment in remission. Methods. Twenty three euthymic patients with bipolar disorder were matched, on a case-by-case basis, to twenty-one healthy subjects in the control group, for the presence of the symptoms of depression. The patients and the control group were tested with a battery of neuropsychological tests. Results. Impairments were found in the patients compared with the control group in tests of verbal learning and memory and in tests of executive function. Verbal learning and memory, as well as executive functions, did not correlate either with the clinical indices of patients, or with the demographic and baseline clinical measures of depression. Conclusion. Impaired verbal learning and memory and executive functions may represent a trait rather than the state variables in bipolar disorder.

Neurocognitive impairment in euthymic patients with bipolar affective disorder

BACKGROUND

Persistent impairments in neurocognitive function have been described in patients with bipolar disorder whose disease is in remission. However, methodological issues such as the effect of residual mood symptoms and hypercortisolaemia may confound such studies.

AIMS

To assess neurocognitive functioning in prospectively verified euthymic patients with bipolar disorder.

METHOD

Sixty-three patients with bipolar disorder and a matched control group completed a comprehensive neurocognitive test battery. Euthymia was confirmed in the patient group by prospective clinical ratings over 1 month prior to testing. Saliva samples were collected to profile basal cortisol secretion.

RESULTS

Patients were significantly impaired across a broad range of cognitive domains. Across the domains tested, clinically significant impairment was observed in 3% to 42% of patients. Deficits were not causally associated with residual mood symptoms or hypercortisolaemia.

CONCLUSIONS

Neurocognitive impairment persists in patients whose bipolar disorder is in remission. This may represent a trait abnormality and be a marker of underlying neurobiological 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.

Cognition in mania and depression: psychological models and clinical implications

Affective disorders, including bipolar disorder and major depressive disorder, are highly prevalent throughout the world and are extremely disabling. Diagnostic and Statistical Manual criteria and psychological models strongly implicate cognitive dysfunctions as being integral to our understanding of these disorders. We review the findings from studies that have used neurocognitive tests and functional imaging techniques to explore abnormal cognition in affective disorders. In particular, we highlight the evidence for cognitive dysfunctions that persist into full clinical remission, and the recent trend toward the use of "hot" processing tasks, involving emotionally charged stimuli, as a means of differentiating between the cognitive underpinnings of mania and depression. The clinical relevance of these developments is discussed.

A functional MRI study of working memory task in euthymic bipolar disorder: evidence for task-specific dysfunction

OBJECTIVES

Even when euthymic bipolar disorder patients can have persistent deficits in working memory, but the neural basis of this deficit remains unclear. We undertook an functional magnetic resonance imaging investigation of euthymic bipolar disorder patients performing two working memory paradigms; the two-back and Sternberg tasks, selected to examine the central executive and the phonological loop respectively. We hypothesized that neuronal dysfunction would be specific to the network underlying the executive rather than the phonological loop component of working memory.

METHODS

Twelve right-handed euthymic bipolar I males receiving lithium carbonate monotherapy were matched with 12 controls. The two-back task comprised a single working memory load contrasted with baseline vigilance condition. The Sternberg paradigm used a parametric design incorporating variable working memory load with fixed delay between presentation of an array of items to be remembered and a target item. Functional activation data were acquired during performance of the tasks and were analysed to produce brain activation maps representing significant group differences in activation (ANOVA). Load-response curves were derived from the Sternberg task data set.

RESULTS

There were no significant between-group differences (t-test) in performance of the two-back task, or in 2 x 5 group by memory load ANOVA for the performance data from Sternberg task. In the two-back task, compared with controls bipolar disorder patients showed reductions in bilateral frontal, temporal and parietal activation, and increased activations with the left precentral, right medial frontal and left supramarginal gyri. No between-group differences were observed in the Sternberg task at any working memory load.

CONCLUSIONS

Our findings support the notion that, in euthymic bipolar disorder, failure to engage fronto-executive function underpins the core neuropsychological deficits.

Bipolar disorder: it's all in your mind? The neuropsychological profile of a biological disorder

OBJECTIVE

To compare and contrast the neuropsychological profile of the 3 phases of bipolar disorder (BD) to achieve a better definition of BD and to identify potential state and trait deficits.

METHODS

We conducted a search for English-language papers published in journals from 1965 onward, using the following terms in Medline and Embase: neuropsychology or neuropsychological and BD, depression, mania, and euthymia. We scrutinized suitable subheadings and retrieved familiar papers and literature.

RESULTS

We initially identified more than 100 articles and then excluded reviews and papers that did not directly administer neuropsychological tests. This left 27 papers, which we further examined and the findings of which we tabulated and discussed. Cognitive and executive functioning deficits were found, including set-shifting, verbal fluency, planning, attention, and memory.

CONCLUSIONS

The neuropsychological deficits found in bipolar depression, mania or hypomania, and euthymia provide important insights into the pathophysiology of BD and may, in future studies, form the basis of clinically meaningful subtypes.

Neurocognitive function in clinically stable men with bipolar I disorder or schizophrenia and normal control subjects

BACKGROUND

Patients with bipolar disorder and schizophrenia have been shown to have neurocognitive deficits when compared with control subjects. The degree and pattern of impairment between psychiatric groups have rarely been compared, especially when subjects are psychiatrically stable.

METHODS

Using a standard neurocognitive battery, we compared euthymic outpatients with bipolar disorder (n = 40), stable patients with schizophrenia (n = 20), and subjects with no psychiatric disorder (n = 22). The neurocognitive domains assessed included executive functioning, verbal memory, visual memory, procedural learning, visuoconstructive ability, and language functions. Effect sizes were calculated for each cognitive domain across groups.

RESULTS

Stable schizophrenic subjects demonstrated a generalized cognitive impairment across most domains compared with control subjects, with average effect sizes of .9. Euthymic bipolar subjects were significantly impaired compared with control subjects only in executive functioning (Wisconsin Card Sorting Task) and verbal memory (California Verbal Learning Test) domains (effect sizes in the .8-.9 range). Performance on the executive function measures was bimodal among bipolar subjects, suggesting two subgroups: one with relatively normal and one with impaired executive functioning. No significant differences between the bipolar patient group and control subjects were observed in visuoconstructive ability, procedural learning, or language function.

CONCLUSIONS

Both euthymic bipolar subjects and relatively stable schizophrenic subjects differed from control subjects in neurocognitive function. Among schizophrenic subjects, a generalized cognitive impairment was observed, and the degree of impairment was greater in the schizophrenic compared with the bipolar subjects. Subjects with bipolar disorder were impaired in two specific domains (verbal memory and executive function). Furthermore, within the bipolar group there was a subset with relatively normal executive functioning and a subset with significant impairment. Possible reasons for the persistence of these neurocognitive deficits in some subjects with bipolar disorder during periods of euthymia are reviewed.

Evidence for continuing neuropsychological impairments in depression

BACKGROUND

Neuropsychological deficits have been reported in patients with major depressive disorder (MDD) during an acute episode of MDD. Little is known whether these abnormalities persist when patients are remitted. The purpose of the present study was to describe the neuropsychological functioning of fully remitted, unmedicated patients with a history of MDD by focusing on tasks related to prefrontal cortex functioning.

METHODS

Twenty-eight young to middle-aged, unmedicated, fully remitted patients with MDD were compared to 23 healthy control subjects on tasks from the Cambridge Automated Neuropsychological Test Battery (CANTAB) and the California Verbal Learning Test (CVLT).

RESULTS

Patients with remitted MDD relative to controls were impaired on tasks of rapid visual information processing (RVIP), psychomotor performance and spatial working memory (SWM). After correction for residual depressive symptoms, deficits in sustained attention remained significant.

LIMITATIONS

CANTAB tasks are not equated for difficulty, and difficulty differences between the CANTAB tasks and the CVLT are not known.

CONCLUSIONS

These findings suggest deficits in sustained attention as vulnerability marker for MDD. The functional importance of this finding and the neuronal networks involved remain to be elucidated.

Set shifting in anorexia nervosa: an examination before and after weight gain, in full recovery and relationship to childhood and adult OCPD traits

Deficits in set shifting tasks are present in anorexia nervosa (AN), but it is not known whether these deficits are traits independent of current disease or nutritional status or merely a temporary consequence of starvation or psychopathology. The aims of the present study were to determine if set-shifting sub-optimal performance are state or trait-related by examining set shifting in patients with current or past AN, and the extent of association of these deficits with obsessive compulsive traits and behaviours. To achieve this we examined set shifting abilities in three groups of subjects: (a) AN patients with current illness, prior to receiving treatment (AN); (b) people with past AN currently in long term recovery (ANRec) and a healthy comparison group (HC). We also longitudinally followed up a subset for the AN group who showed weight recovery in response to in patient treatment (ANWR). We administered a group of set shifting tests, which included cognitive, perceptual and motor shifting tasks. A semi-structured interview was obtained to ascertain obsessive compulsive personality disorder (OCPD) traits as a child and adult. Set-shifting difficulties were observed in the AN group, but to a lesser extent in the ANRec group. In the AN group these difficulties did not show any improvement follow re-testing after weight recovery. Performance on set shifting tasks was associated with childhood rigidity and inflexibility. Some aspects of set shifting sub-optimal performance in AN appear to be a trait rather than a state marker.