Auditory sensory memory in schizophrenia: inadequate trace formation?

This study explored duration mismatch negativity reductions observed in individuals with schizophrenia, in particular, the relationship to behavioural measures of temporal discrimination and two event-related potential (ERP) components occurring during the first phase of auditory sensory memory. Twenty-two patients with a DSM-IV and ICD-10 diagnosis of schizophrenia and 25 healthy comparison volunteers participated in a behavioural and an ERP testing session. Both groups performed equivalently on behavioural estimates of filled interval duration discrimination and gap detection. In contrast, electrophysiological measures revealed a significant reduction in patients' duration mismatch negativity and a significant difference in patients for the pattern of N100 facilitation over short stimulus onset asynchronies. Whilst behavioural results indicate intact temporal processing of filled intervals and equal temporal resolution limits in schizophrenia, both ERP measures indicated differences in auditory processing that may be traced to activity occurring during the first 250 ms. Results highlight the possibility of abnormalities in the process of auditory trace formation and temporal summation in schizophrenia.     

Can music alleviate cognitive dysfunction in schizophrenia?

It has recently been reported that students performed relatively better on cognitive tasks after listening to music. Conceivably, music might reduce the level of arousal in subjects who are tense, thereby improving their performance. A test case would be schizophrenic subjects, noted for poor performance on tasks demanding attention, who have been characterized as suffering from hyperarousal, which mediates these attentional deficits. We investigated whether cognitive task performance could be facilitated by music in schizophrenics and report a beneficial effect.     

Ziprasidone-induced cognitive enhancement in schizophrenia: specificity or pseudospecificity?

OBJECTIVE: Ziprasidone may improve cognition in schizophrenia; however, this could be related to clinical symptom improvement, reflecting "pseudospecificity". We tested the hypothesis that ziprasidone improves cognition in the absence of clinical improvement. METHODS: We conducted a 12-week, open-label study of ziprasidone in 10 schizophrenia patients who met non-response criteria (<20% reduction in BPRS scores over 12 weeks). We conducted comprehensive cognitive testing and assessed change from baseline to end of study. RESULTS: We detected significant improvement on three measures of episodic memory (p<0.01) in these clinically non-responsive patients. Trend-level improvements were noted on tests involving processing speed and executive function. CONCLUSIONS: These data suggest that ziprasidone has cognitive benefits unrelated to an influence on other disease parameters.     

Cancer in schizophrenia: is the risk higher or lower?

Studies exploring the relationship between schizophrenia and cancer have shown conflicting results. Our study explores this association in three Jewish-Israeli population groups defined by their continent/place of birth (Israel, Europe-America, and Africa-Asia). The identification of the patients was made through the linkage of the nationwide psychiatric and cancer registries. The incidence of cancer in patients diagnosed with schizophrenia was compared with the incidence in the general population. The results showed that the cancer standardized incidence ratios (SIRs) for all sites were significantly lower among men and women with schizophrenia, 0.86 [95% confidence interval (CI) 0.80-0.93] and 0.91 (95% CI 0.85-0.97), respectively. This reduced overall risk was clearest for those born in Europe-America, both men (SIR 0.85, 95% CI 0.74-0.97) and women (SIR 0.86, 95% CI 0.77-0.94). Among women diagnosed with schizophrenia, the SIR was statistically higher for cancer in the breast among those born in Asia-Africa (1.37, 95% CI 1.12-1.63) and in the corpus uteri among the Israel-born (2.75, 95% CI 1.69-3.81) than among their counterparts in the general population. Lung cancer was significantly higher in men born in Asia-Africa diagnosed with schizophrenia than in the respective comparison population group (1.58, 95% CI 1.13-2.2). Our findings, and those of the literature, justify conducting a multinational study that includes identification of cancer-related risk factors among patients with schizophrenia and their families, and information on the use of psychotropic medications. This effort may clarify an epidemiological puzzle that remains outstanding.     

Anhedonia in schizophrenia and major depression: state or trait?

Background  

In schizophrenia and major depressive disorder, anhedonia (a loss of capacity to feel pleasure) had differently been considered as a premorbid personological trait or as a main symptom of their clinical picture. The aims of this study were to examine the pathological features of anhedonia in schizophrenic and depressed patients, and to investigate its clinical relations with general psychopathology (negative, positive, and depressive dimensions).     

Low birthweight in schizophrenia: prematurity or poor fetal growth?

In the general population, low birthweight (LBW) is associated with neurological and psychological problems during childhood and adolescence. LBW may result from premature birth or poor fetal growth, and the independent effects of these two events on childhood development are not fully understood. The rate of low weight births is increased in schizophrenia and is associated with social withdrawal during childhood and an early onset of illness. However, it is unclear whether this LBW reflects poor fetal growth or premature birth, or whether these two risk factors have distinct implications for childhood functioning and age at onset of schizophrenia. Subjects included 270 patients with schizophrenia for whom a detailed history of obstetric events could be obtained. The rate of low weight births was high and was associated with poorer premorbid functioning and an earlier age at illness onset. The rate of both premature births and poor fetal growth was high relative to the normal population. Prematurity, but not poor fetal growth, was associated with premorbid social withdrawal and an early age at illness onset. Poor fetal growth, but not prematurity, was associated with low educational achievement. These results suggest that poor fetal growth and prematurity are associated with distinct patterns of childhood maladjustment in individuals who develop schizophrenia.     

Visual sensory processing deficits in schizophrenia: is there anything to the magnocellular account?

Visual processing studies have repeatedly shown impairment in patients with schizophrenia compared to healthy controls. Electroencephalography (EEG) and, specifically, visual evoked potential (VEP) studies have identified an early marker of this impairment in the form of a decrement in the P1 component of the VEP in patients and their clinically unaffected first-degree relatives. Much behavioral and neuroimaging research has implicated specific dysfunction of either the subcortical magnocellular pathway or the cortical visual dorsal stream in this impairment. In this study, EEG responses were obtained to the contrast modulation of checkerboard stimuli using the VESPA (Visual Evoked Spread Spectrum Analysis) method. This was done for a high contrast condition and, in order to bias the stimuli towards the magnocellular pathway, a low contrast condition. Standard VEPs were also obtained using high contrast pattern reversing checkerboards. Responses were measured using high-density electrical scalp recordings in 29 individuals meeting DSM-IV criteria for schizophrenia and in 18 control subjects. Replicating previous research, a large (Cohen's d=1.11) reduction in the P1 component of the VEP was seen in patients when compared with controls with no corresponding difference in the VESPA response to high contrast stimuli. In addition, the low-contrast VESPA displayed no difference between patients and controls. Furthermore, no differences were seen between patients and controls for the C1 components of either the VEP or the high-contrast VESPA. Based on the differing acquisition methods between VEP and VESPA, we discuss these results in terms of contrast gain control and the possibility of dysfunction at the cortical level with initial afferent activity into V1 along the magnocellular pathway being intact when processing is biased towards that pathway using low contrast stimuli.     

Word stress processing in specific language impairment: Auditory or representational deficits?

Abstract

Word stress processing has repeatedly been reported to be affected in specific language impairment (SLI) with potential consequences for various aspects of language development. However, it still remains unresolved whether word stress impairments in SLI are due to deficits in basic auditory processing or to a degraded phonological representation or both. We addressed this question examining an unselected sample of 10 children with SLI and 11 typically developing (TD) children, aged about 8 years, with respect to their basic auditory processing (duration and skewness discrimination) and phonological representation of prosodic (word stress) and segmental (consonant) contrasts. Our results show lower performance of the SLI group compared to the TD group in all tasks. Crucially, two subgroups of children with SLI emerged from our analyses: While one group was impaired in basic auditory perception, particularly affecting duration discrimination, the other showed no significant auditory processing deficits but a representational impairment.     

Sensorimotor dysfunction of grasping in schizophrenia: a side effect of antipsychotic treatment?

BACKGROUND: Antipsychotic treatment in schizophrenia is frequently associated with extrapyramidal side effects. Objective behavioural measures to evaluate the severity of extrapyramidal side effects in the clinical setting do not exist. OBJECTIVES: This study was designed to investigate grasping movements in five drug naive and 13 medicated subjects with schizophrenia and to compare their performance with that of 18 healthy control subjects. Deficits of grip force performance were correlated with clinical scores of both parkinson-like motor disability and psychiatric symptom severity METHODS: Participants performed vertical arm movements with a handheld instrumented object and caught a weight that was dropped into a handheld cup either expectedly from the opposite hand or unexpectedly from the experimenter's hand. The scaling of grip force and the temporospatial coupling between grip and load force profiles was analysed. The psychiatric symptom severity was assessed by the positive and negative symptom score of schizophrenia and the brief psychiatric rating scale. Extrapyramidal symptoms were assessed by the unified Parkinson's disease rating scale. RESULTS: Drug naive subjects with schizophrenia performed similar to healthy controls. In contrast, medicated subjects with schizophrenia exhibited excessive grip force scaling and impaired coupling between grip and load force profiles. These performance deficits were strongly correlated with the severity of both extrapyramidal side effects related to antipsychotic therapy and negative symptoms related to the underlying pathology. CONCLUSIONS: These data provide preliminary evidence that deficits of sensorimotor performance in schizophrenia are, at least in part, related to the side effects of antipsychotic treatment. The investigation of grasping movements may provide a sensitive measure to objectively evaluate extrapyramidal side effects related to antipsychotic therapy.     

Auditory dysfunction in patients with Huntington’s disease

Objective

Huntington’s disease (HD) is an autosomal, dominantly inherited, neurodegenerative disease. The main clinical features are motor impairment, progressive cognitive deterioration and behavioral changes. The aim of our study was to find out whether patients with HD suffer from disorders of the auditory system.

Disordered verbalizations in schizophrenia: a speech disturbance or thought disorder?

This research provides empirical data relevant to the long-standing theoretical issue of whether disordered speech in schizophrenia should be viewed as a speech disturbance or a thought disorder. The study analyzed whether schizophrenia patients with disordered speech on one test also show strange nonverbal behavior and unrealistic ideas on other assessments. One hundred eighty-four patients, including 55 schizophrenia patients, were assessed at the acute phase and followed up twice, over 4.5 years. Patients were assessed (1) with a standardized measure that can elicit disordered speech, (2) with a different measure that can elicit an atypical sorting of objects and an intermingling of personal ideas, and (3) for delusions (unrealistic thinking). Schizophrenia patients with disordered speech on the Proverbs Test also (1) sorted objects strangely on the Object Sorting Test (P <.05), (2) showed an intermingling of personal ideas into their thinking (P <.01), and (3) had delusional ideas when assessed at two successive follow-ups over a multiyear period (P <.001). The data suggest that most schizophrenia patients and other psychotic patients with disordered speech also show strange nonverbal behavior and unrealistic ideas/beliefs. These data support a theoretical framework in which disordered speech in schizophrenia and other types of psychotic patients is viewed as not just due to a speech disorder, but is often part of a broader constellation that includes gross reality distortions, strange behavior and ideas, and disordered thinking.     

Abnormalities in thalamic neurophysiology in schizophrenia: Could psychosis be a result of potassium channel dysfunction?

Psychosis in schizophrenia is associated with source-monitoring deficits whereby self-initiated behaviors become attributed to outside sources. One of the proposed functions of the thalamus is to adjust sensory responsiveness in accordance with the behavioral contextual cues. The thalamus is markedly affected in schizophrenia, and thalamic dysfunction may here result in reduced ability to adjust sensory responsiveness to ongoing behavior. One of the ways in which the thalamus accomplishes the adjustment of sensory processing is by a neurophysiological shift to post-inhibitory burst firing mode prior to and during certain exploratory actions. Reduced amount of thalamic burst firing may result from increased neuronal excitability secondary to a reported potassium channel dysfunction in schizophrenia. Pharmacological agents that reduce the excitability of thalamic cells and thereby promote burst firing by and large tend to have antipsychotic effects.     

Cannabis and cognitive dysfunction: parallels with endophenotypes of schizophrenia?

Currently, there is a lot of interest in cannabis use as a risk factor for the development of schizophrenia. Cognitive dysfunction associated with long-term or heavy cannabis use is similar in many respects to the cognitive endophenotypes that have been proposed as vulnerability markers of schizophrenia. In this overview, we examine the similarities between these in the context of the neurobiology underlying cognitive dysfunction, particularly implicating the endogenous cannabinoid system, which plays a significant role in attention, learning and memory, and in general, inhibitory regulatory mechanisms in the brain. Closer examination of the cognitive deficits associated with specific parameters of cannabis use and interactions with neurodevelopmental stages and neural substrates will better inform our understanding of the nature of the association between cannabis use and psychosis. The theoretical and clinical significance of further research in this field is in enhancing our understanding of underlying pathophysiology and improving the provision of treatments for substance use and mental illness.