Enrico Daneluzzo

Sensorimotor gating and habituation evoked by electro-cutaneous stimulation in schizophrenia

The present study has been performed in order to evaluate two relevant phenomena related to startle reflex (SR) evoked by electro-cutaneous stimulation in schizophrenic patients: 1) the effect of different interstimulus intervals on R1, R2 magnitude and on R2 latency in schizophrenia in order to verify if the gating effect influences all blink reflex (BR) parameters and 2) to replicate and extend our previous data on SR habituation. Our data have confirmed the existence of an impairment of habituation and an abnormal facilitatory effect of R1 component of BR in schizophrenics compared to healthy controls. The present study provides further evidence of specific defective mechanisms of information processing in schizophrenia. The methodology used for SR paradigm appears to be founded on a sound research basis and represents an advantageous paradigm for assessing attentional variables of information processing in mental disorders.

Cognitive function in euthymic bipolar patients, stabilized schizophrenic patients, and healthy controls

Abstract Studies on cognitive function in bipolar disorder have led to contrasting results and few data are available on affected subjects during the euthymic phase. In the present study we investigated the cognitive function of a cohort of bipolar ( n =40) and schizophrenic ( n =66) patients compared to healthy controls ( n =64). Patients were evaluated in the outpatient setting over at least 3 months using a computerized version of Wisconsin Card Sorting Test. Schizophrenic patients showed the worst performance while that of the bipolar patients was somewhere between schizophrenic and controls. A discriminant analysis was able to classify correctly 60.59% of the subjects (schizophrenics 48.5%, bipolars 40%; healthy controls 85.9%). The scores of the Wisconsin Card Sorting Test were entered into a principal component analysis, which yielded a 2-factor solution. Even in that analysis bipolar patients showed intermediate features in comparison with the other groups. These data indicate that bipolar patients have subtle neurocognitive deficits even after the resolution of an affective disorder. As well as observing quantitative differences between groups, the results show different dimensions of cognitive performance within groups suggesting that the deficit of euthymic bipolars could be a dishomogeneous entity, probably more heterogeneous than that in schizophrenia. Studies administering a more complete neuropsychological battery could further clarify the nature and meaning of the cognitive deficits in schizophrenia and bipolar disorder.

Processing of context information in schizophrenia: relation to clinical symptoms and WCST performance

Failure in contextual information processing has been hypothesized as being the single function responsible for several impairments in cognitive tasks and symptoms, through an involvement of the prefrontal cortex, in patients with schizophrenia. A variant of the Continuous Performance Test (CPT) designed specifically to elicit deficits in the processing of contextual information has been administered to 20 schizophrenic patients and 20 healthy controls. The relation to Wisconsin Card Sorting Test (WCST), relatively specific to prefrontal damage and executive dysfunctioning, and clinical status by using scales for the assessment of positive, negative symptoms and outcome has been investigated. The data show that multi-episode schizophrenic patients manifest inability to use contextual information to inhibit habitual response to an ambiguous stimulus and to maintain information across delay, without a general attention deficit. We also found a relationship between contextual reasoning and WCST unique errors, hallucinations, formal thought disorders, and outcome evaluation. Our results further support the hypothesis that the deficit of contextual reasoning could account for cognitive impairments and symptoms of patients with schizophrenia.

Insight and neuropsychological function in patients with schizophrenia and bipolar disorder with psychotic features.

Objectives: This study investigates the pattern of association between patient unawareness of illness and neuropsychological tests of frontal lobe function in subjects with schizophrenia and bipolar disorder (BD) with psychotic features. Method: We administered the Wisconsin Card Sort Test (WCST) and a shortened version of the Scale to Assess Unawareness of Mental Disorder (SUMD) to a sample of 64 patients with psychosis (42 with schizophrenia and 22 with BD). Results: None of the correlations between WCST scores and insight scores were statistically significant, either in the total group or in each group analyzed separately. Further, no differences were seen in insight scores between sexes and between the diagnostic groups. Conclusions: The 3 insight dimensions (that is, awareness of mental disorder, awareness of social consequences of mental disorder, and awareness of the benefits of medication) do not appear to be associated with frontal impairment, as measured by the WCST.

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

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

No deficit in Wisconsin Card Sorting Test performance of schizophrenic patients' first-degree relatives.

The Wisconsin Card Sorting Test (WCST) was administered to 92 schizophrenic patients, 25 first-degree relatives and 60 normal subjects in order to investigate whether this task could be considered a trait marker of vulnerability to schizophrenia. The schizophrenic patients performed significantly worse than either their relatives or normal subjects, but unaffected relatives did not differ from controls. Our results suggest that WCST performance is more likely a feature inherent to the disease process rather than an index of the genetic susceptibility to the illness.

Startle reflex habituation in functional psychoses: A controlled study

The habituation of the startle reflex in a paradigm using electrical stimulation was studied in 17 psychotic patients and 18 healthy controls. The magnitude of the R2 component of the blink reflex differed between the groups (ANOVA, F = 5.81; P = 0.022) and during the course of trials (F = 25.72; P < 0.0001). Furthermore a statistically significant interaction of diagnosis x trials (F = 3.34; P = 0.022) emerged suggesting that an impairment in habituation of startle is present in patients but not in healthy controls despite a comparable reactivity.

Association between Striatal Reduction and Poor Wisconsin Card Sorting Test Performance in Patients with Schizophrenia

Several findings support the hypothesis that the striatum is implicated in executive functions and in the modulation of goal-directed behavior, and could play a key role in the pathophysiology and in the production of symptoms and signs in schizophrenia. We have studied the relationship between the objective measures of the striatal structures, as evaluated by magnetic resonance imaging (MRI), and the Wisconsin Card Sorting Test (WCST) performance in a schizophrenic sample. Thirty-five schizophrenic patients underwent MRI scans of striatal structure and neuropsychological evaluation of executive functions by WCST. Poor WCST performers had a reduction of the left caudate nucleus and putamen, and right total striatum when compared to 24 healthy controls. Significant correlation coefficients were also observed between neuropsychological indexes and left striatal measures. The findings suggest the existence of a relationship between abnormalities of striatal structure and abnormal executive-type or organizational cognitive functions.

Patterns of Comorbidity among DSM-III-R Personality Disorders

The aim of this study was to examine patterns of comorbidity among personality disorders (PDs) in a sample of 156 psychiatric inpatients. PDs were assessed with Semistructured Clinical Interview for DSM-III-R Personality Disorders. To determine significant co-occurrence among axis II diagnoses, odds ratio and the percent of co-occurrence of pairs of disorders were calculated. Both statistical methods revealed high rates of comorbidity: significance association was found for 36 pairs of disorders using the percent of co-occurrence, and for 22 pairs of disorders using the odds ratio. These results support the concept of ‘apparent comorbidity’ for most PDs, deriving from conceptual and definitional artifacts or from a ‘state-biasing effect’. In light of these observations, a categorical approach to PDs, resulting in a list of diagnoses, appears useless in psychiatric practice. A dimensional classification is probably better suited for PDs, improving the understanding of personality psychopathology and its clinical implications.

Schizotypal personality questionnaire and wisconsin card sorting test in a population of DSM-III-R schizophrenic patients and control subjects

Phenomenological, biological, genetic, treatment-response, and outcome data support a link between schizotypal personality disorder (SPD) and schizophrenia. Furthermore, SPD and normal schizotypy also seem connected, although the relationship can at times be ambiguous. In this regard, this study was conducted to test the hypothesis of a possible association between neurocognitive performance evaluated by the Wisconsin Card Sorting Test (WCST) and schizotypal personality traits evaluated by the Schizotypal Personality Questionnaire (SPQ) in a nonclinical sample and a sample of schizophrenic patients. The main finding of the study was that WCST performance was correlated with SPQ (total and subscale) scores in the control group; on the contrary, in the patients, the relationship between WCST and SPQ scores was weaker. Taken together, our results seem to support the hypothesis that different cognitive aspects (i.e., elementary WCST subcomponent scores) correlate differentially with some SPQ schizotypal traits in a group of nonclinical subjects. This report underlines the relevance of studying normal subjects within the brain-behavior paradigm to highlight the brain-behavior relationship in the mental illness.