José Salazar-Fraile

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

OBJECTIVE Many studies have reported that cognitive ability may be predictive of the functional outcome for patients with schizophrenia. However, no study has prospectively examined these aspects in schizophrenia and bipolar disorders simultaneously. The present study attempted to analyze if neurocognition and clinical status predicts the real-life functioning for patients with schizophrenia or bipolar I disorder, using a longitudinal design. METHOD Forty-seven schizophrenic and 43 bipolar I outpatients were assessed twice with a neurocognitive battery (Executive Functions, Working Memory, Verbal Memory, Visual Memory, Visual-Motor Processing, Vigilance, Vocabulary and Motor Speed tasks), clinical scales (the Positive and Negative Symptom Scale, the Hamilton Rating Scale for Depression and the Clinician Administered Rating Scale for Mania) and functional outcome measures (the Global Assessment of Functioning Scale, the WHOs Disability Assessment Scale and occupational adaptation level) over a one-year follow-up period. The cognitive performance of the patients was compared, at baseline and one year later, with that of 25 healthy subjects. RESULTS In schizophrenia patients, global functioning one year later was predicted by a composite neurocognitive score and three specific domain (verbal memory, motor speed, vocabulary). Symptoms appeared to explain less of the variance in functioning. In bipolar I patients, changes in the composite neurocognitive score over one year, deficits in the visual/motor processing domain, severity of symptoms (psychotic, excitatory and affective symptoms) and premorbid adjustment at the first assessment were the variables that better predicted functioning or disability changes over follow-up period. CONCLUSIONS Although the relationships between cognition, symptoms and functional capacity differ for schizophrenia or bipolar I patients, neuropsychological performance seems to be a principal longitudinal predictor of functioning in both disorders. Baseline neurocognition and cognitive changes over 12 months predicted changes in functioning over the same period, but only in bipolar I patients. These cognitive domains could be potential neurocognitive endophenotypes (endophenocognitypes) with regard to bipolar I disorder.

Neurocognitive endophenotypes (Endophenocognitypes) from studies of relatives of bipolar disorder subjects: A systematic review

BACKGROUND There is growing interest to research neurocognition as a putative endophenotype for subjects with bipolar disorders (BD). The authors sought to review the available literature focused on relatives of subjects with bipolar disorder (BD-Rels) and identify suitable cognitive candidates to endophenotypes or endophenocognitypes. METHOD A systematic review was conducted in Medline, EMBASE and PsycINFO databases (1980-July 2007), supplemented with a manual search of reference lists. RESULTS Twenty-three cross-sectional papers of discordant twins (4 studies), genetic high-risk subjects (7), and different BD-Rel groups (12) met the inclusion criteria and evaluated 532 BD-Rels. Impairments on the broad domain of verbal learning/memory were found in 6 out of 11 studies (54%), as well as in 3 of 9 reports (33%) of working memory. Moreover, BD-Rels showed deficits in visual-spatial learning and memory (1/6 reports; 17%), alternating attention (1/8; 12.5%), psychomotor speed (2/10; 20%), and abstraction/cognitive flexibility, sustained attention and selective attention (2/8 each; 25%). Scores of general intelligence were lower than those of controls in 2/16 (12.5%) reports, but fell well within the average range in all studies. No study that assessed immediate memory or verbal fluency (6 each) reported impairments in BD-Rels. Finally, language, social cognition, and motor and planning skills are neglected areas of research. CONCLUSIONS Overall, the neurocognitive profile in BD-Rels is still unclear, and the evidence in support of the presence of cognitive deficits seems quite sparse. Verbal learning/memory and verbal working memory seem to be the most suitable endophenocognitypes for BD. Conversely, healthy family members would have an intact performance on immediate memory, verbal fluency, and probably on general intelligence. The possibility that BD-Rels show less cognitive efficiency compared to healthy controls also on other functions must be addressed by future studies with larger samples, comprehensive neuropsychological assessments, and, ideally, longitudinal designs.

Specificity of cognitive deficits in bipolar disorder versus schizophrenia. A systematic review.

Background: More and more epidemiological, genetic and neuroimaging studies show similarities between bipolar disorder (BD) and schizophrenia (SZ). Cognitive functions are known to be highly impaired in SZ and are increasingly studied in BD. When both populations are compared, the conclusions appear to be contradictory. The purpose of this review is to help define the profile of cognitive deficits in BD and in SZ. Methods: A systematic review of the literature of neuropsychological studies comparing BD and SZ was made, beginning in January 1990 and ending in January 2005. Thirty-eight studies met the required quality criteria and were included in this review. Results: Bipolar patients exhibit extensive cognitive abnormalities with a pattern of deficits that is not unique to this disease. However, when compared to schizophrenic patients, bipolar patients demonstrate a lesser degree of deficits, particularly concerning premorbid and current intelligence quotient and perhaps attention, verbal memory and executive functions. When looking into effect sizes, there seem to be different profiles even in studies finding no significant differences. Conclusions: The neuropsychological differences reported between both groups could be due to the presence of psychotic features, to environmental factors (stressful events, duration of the disease and number of hospitalisations) and could also be related to differences during the neurodevelopmental phase. Further studies should confirm whether these results are truly related to different neurobiological backgrounds.

Persistent Cognitive Dysfunctions in Bipolar I Disorder and Schizophrenic Patients: A 3-Year Follow-Up Study

Background: Neurocognitive impairment has consistently been considered a central and stable feature in schizophrenia. As this possibility has been far less studied in bipolar disorder, we aimed to prospectively investigate the stability and specificity of cognitive performance in bipolar disorder compared to schizophrenia. Methods: Fifteen DSM-IV bipolar type I patients and 15 schizophrenic patients were assessed twice with a comprehensive neuropsychological battery and the Positive and Negative Syndrome Scale over a 3-year follow-up. The cognitive performance of the groups was compared at baseline and 3 years later as a mean with that of 26 healthy volunteers. Endpoint and baseline assessments were also compared for each patient group in order to evaluate the stability of cognitive impairment. Results: At both time points, bipolar and schizophrenic patients showed significant deficits on most of the cognitive tasks compared to healthy subjects. Overall, the cross-sectional cognitive profile was similar for both patient groups. Moreover, after controlling for age and length of illness, the two groups’ cognitive function did not differ over time in any test. With the exception of the Stroop color-word interference task, performance at baseline for each test but neither length of illness nor diagnostic category predicted the endpoint performance. Conclusion: This preliminary study suggests that cognitive impairment is also mainly stable over time in bipolar I disorder and thus not specific to schizophrenia.

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

Neurocognitive impairments are well documented in patients with schizophrenia and their healthy first-degree biological relatives. Less is known about neuropsychological performance in bipolar disorders, but some studies indicate that, compared to schizophrenia, bipolar disorder displays a similar profile pattern with less severe deficits. The genetic and environmental contributions to the development of neurocognitive deficits are also unclear. This study explored the effect of a family history (FH) of psychotic disorders in first-degree relatives on a variety of cognitive domains (abstraction and flexibility, verbal fluency, verbal memory, motor activity and visual-motor processing/attention) in 30 patients with schizophrenia, and 24 type I bipolar patients. After adjusting the results for age, gender, education level and pre-morbid intelligence, patients with schizophrenia or bipolar disorder with positive FH (n=18) performed significantly worse than patients with negative FH (n=36) on the visual-motor processing/attention domain. These findings were independent of the specific diagnosis. Moreover, when logistic regression analysis was performed, poor Digit Symbol performance was the only predictor of belonging to the positive FH group. Our results are compatible with the existence of some common genetic factors between the illnesses, as well as the involvement of identical, or at least similar, disordered brain systems in both disorders. These findings are discussed within the context of the continuum model of psychosis.

Similar effect of family history of psychosis on Sylvian fissure size and auditory P200 amplitude in schizophrenic and bipolar subjects

Several cerebral studies point to the non-specificity of structural and functional changes described in schizophrenia and bipolar disorders. Furthermore, the origin of these changes is still unclear. The present study investigated the effect of a family history (FH) of psychotic disorders in first-degree relatives on computed tomographic (CT) measures (ventricular, cerebral and Sylvian fissure size) and auditory event-related potentials (amplitudes and latencies of peak components in oddball paradigms) in 30 schizophrenic patients and 24 bipolar type I patients. We found a significant correlation between FH and the size of the right Sylvian fissure, and between FH and auditory P200 amplitude. More specifically, the schizophrenic and bipolar patients with negative FH (n=36) had larger right Sylvian fissures and smaller P200 amplitude than patients with positive FH (n=18). These findings were independent of the specific diagnosis, gender, and age of subjects. Our results suggest some underlying process common to schizophrenia and bipolar I disorder, and they provide support for the continuum view of the nosologic structure of psychotic illness.

Abnormal motor asymmetry only during bimanual movement in schizophrenic patients compared with healthy subjects

In schizophrenia, research on motor asymmetry has focused on the direction and the degree of handedness using unimanual motor tests and tasks. However, typically both hands collaborate in the production of most manual movements. This study explored motor asymmetry exhibited during unimanual and bimanual tasks in schizophrenic and healthy subjects using a new experimental motor battery. Specifically, the authors investigated the motor indices of laterality during finger-tapping and hand-turning tasks in four unimanual and four bimanual conditions in 84 schizophrenic and 31 healthy subjects, all right-handed. The schizophrenic patients showed reduced motor asymmetries only during bimanual tapping compared with healthy subjects due to reduction in right-hand performance. These results stress the importance of considering bimanual conditions in the assessment of motor asymmetries, and suggest that it is necessary to use bimanual tasks to test hypotheses about abnormal motor lateralization in schizophrenia.

The switch from conventional to atypical antipsychotic treatment should not be based exclusively on the presence of cognitive deficits. A pilot study in individuals with schizophrenia

BackgroundAtypical antipsychotics provide better control of the negative and affective symptoms of schizophrenia when compared with conventional neuroleptics; nevertheless, their heightened ability to improve cognitive dysfunction remains a matter of debate. This study aimed to examine the changes in cognition associated with long-term antipsychotic treatment and to evaluate the effect of the type of antipsychotic (conventional versus novel antipsychotic drugs) on cognitive performance over time.MethodsIn this naturalistic study, we used a comprehensive neuropsychological battery of tests to assess a sample of schizophrenia patients taking either conventional (n = 13) or novel antipsychotics (n = 26) at baseline and at two years after.ResultsContinuous antipsychotic treatment regardless of class was associated with improvement on verbal fluency, executive functions, and visual and verbal memory. Patients taking atypical antipsychotics did not show greater cognitive enhancement over two years than patients taking conventional antipsychotics.ConclusionsAlthough long-term antipsychotic treatment slightly improved cognitive function, the switch from conventional to atypical antipsychotic treatment should not be based exclusively on the presence of these cognitive deficits.