Vittorio Di Michele

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.

Magnetic resonance imaging findings of amygdala- anterior hippocampus shrinkage in male patients with schizophrenia

Recent magnetic resonance imaging (MRI) studies found abnormalities of medial temporal lobe and basal ganglia structures. We used an inversion recovery (IR) protocol with the assistance of the Talairach atlas to identify neuroanatomical regions of interest in 19 male schizophrenic patients and 14 matched control subjects. The patient group showed smaller amygdala-hippocampus volume as compared with normal control subjects. This finding was more pronounced for the left side, although no diagnosis X side interaction was present. Third ventricle volume was also enlarged in schizophrenic patients. Trends toward an overall reduction of basal ganglia (striatum and lenticular nucleus) and limbic structures and toward an increase in ventricle-brain ratio were also seen. The study confirms previous evidence of mesial temporal lobe shrinkage, more evident on the left side in a group of relapsing noninstitutionalized male schizophrenic patients.

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.

Deficit of social cognition in subjects with surgically treated frontal lobe lesions and in subjects affected by schizophrenia

The ability of humans to predict and explain other people’s behaviour by attributing independent mental states such as desires and beliefs to them, is considered to be due to our ability to construct a “Theory of Mind”. Recently, several neuroimaging studies have implicated the medial frontal lobes as playing a critical role in a dedicated “mentalizing” or “Theory of Mind” network in the human brain. In this study we compare the performance of patients with right and left medial prefrontal lobe lesions in theory of mind and in social cognition tasks, with the performance of people with schizophrenia.We report a similar social cognitive profile between patients with prefrontal lobe lesions and schizophrenic subjects in terms of understanding of false beliefs, in understanding social situations and in using tactical strategies. These findings are relevant for the functional anatomy of “Theory of Mind”.

Temporal lobe structure by magnetic resonance in bipolar affective disorders and schizophrenia

Sixteen bipolar and 10 schizophrenic patients, all male, underwent magnetic resonance imaging scans. Areas derived from five coronal sections were measured separately and then summed to obtain an estimate of temporal lobe volumes. Schizophrenics showed a reduction of temporal lobe areas in those sections corresponding to the hippocampal region. This finding was more pronounced for the left side, although no diagnosis by side interaction was present. Temporal lobe volume was also reduced in schizophrenics. When a lateralized difference was present, the right temporal lobe was larger than the left in both patient groups.

The natural course of schizophrenia and psychopathological predictors of outcome. A community-based cohort study.

The natural course of schizophrenia is extremely heterogeneous and generally considered unpredictable. This prospective research investigated the natural course of schizophrenia in a community-based population linked to an Italian Mental Health Center, looking for the identification of psychopathological predictors of outcome. Forty schizophrenic patients were assessed at baseline in a stabilized phase of illness with clinical scales of psychopathology and social functioning and afterwards were followed up for 36 months. All of them were treated with antipsychotic drugs. According to their symptoms and function scores patients were empirically classified into three groups with a cluster analysis: a group characterized by low symptoms and good functioning, a group with high symptoms and poor functioning and an intermediate group. A crosstabs analysis revealed that the empirical classification correctly predicted long-term outcome. A survival analysis with comparison of distributions (Wilcoxon Gehan test) also revealed significant differences in terms of hospital admission and occurrence of alcohol-related diagnosis across groups. This study suggests that the long-term outcome in schizophrenic patients followed by a community-based mental health service is generally poor and multifaceted. However, outcome may be predicted on the basis of the psychopathological and social functioning profile assessed in a stabilized phase of illness defined with operational criteria.

Acoustic and Electrically Elicited Startle Reaction: Similar Patterns of Habituation and Reflex Modifications in Humans

The present study was performed in order to verify two relevant phenomena related to Startle Reaction in normal subjects: 1) the response habituation, that consists of an exponential decrement of the R2 component of Blink Reflex after repeated identical stimuli, and 2) the modification of R1 magnitude, R2 magnitude and latency when the startle eliciting stimulus is preceded by a warning stimulus. Our data confirm: 1) that habituation is independent of paradigm and type of stimulation (acoustic vs electrocutaneous), and 2) an electrical prestimulus has a facilitatory effect on the R2 latency of the electrically elicited Blink Reflex onset with an inhibition of R2 magnitude. The present study support the view of a systemic supramodal central mechanism of information processing and sensorial gating with super-imposable effects on the different sensorial pathways.

Symptoms and social functioning features in chronic schizophrenia are aggregate in a tripartite structure

OBJECTIVE To verify the association between schizophrenic symptoms and multidimensional variables of social functioning and to look for a possible classification based on an empirical classification outcome oriented. DESIGN Forty chronic schizophrenic patients, with a diagnosis ascertained through clinical interview and diagnostic criteria were enrolled in the study. SETTING All patients were followed in a State Mental Health center and were assessed in a stabilized phase of illness. PRINCIPAL OUTCOME MEASURES: Psychopathological assessment was made with PANSS and CGI. Psychosocial assessment was made with Life Skills Profile and Global Functioning Scale. RESULTS A pervasive correlation among symptoms and psychosocial variables emerged suggesting a unitary concept of behavior related to diagnosis. Factor analysis revealed 2 main components able to explain the 79% of variance. Cluster analysis separated the patients in 3 different groups showing that clinical symptoms are aggregated with specific variables of social functioning. CONCLUSION Schizophrenic symptoms and social functioning are organized in a tripartite structure. It suggests the existence of three different syndromes that are outcome oriented, and compatible with an unitary concept of schizophrenia.

Brain Imaging as a Tool to Investigate Heterogeneity of Schizophrenia: a Magnetic Resonance Study

AbstractThe brain morphology of cerebral measures from magnetic resonance scans of 50 schizophrenic patients and 40 healthy controls was examined using cluster analysis in order to investigate heterogeneity in schizophrenia. This multivariate analysis defined a cluster of schizophrenics only (28% of patient group) with enlarged ventricular sizes, corpus callosum dimensions at the lower limits of the range of controls, and more severe illness. The remaining two clusters produced were composed of mixed subgroups of patients and controls, schizophrenics showing a milder form of illness. The implications of morphological abnormalities and association with negative/positive symptomatology and sporadic/familial dicotomy in these clusters are discussed.