Social network reductions are associated with negative symptoms in schizophrenia.

Background: A recent environmental systems theory of negative symptoms in schizophrenia (SZ) proposes a role for reductions in social networks that exist within microsystems (i.e., the contexts in which social interactions occur).

Timing matters in elaborative processing of positive stimuli: Gamma band reactivity in schizophrenia compared to depression and healthy adults.

Some individuals with schizophrenia report similar feelings of positive affect "in the moment" compared to control participants but report decreased trait positive affect overall. One possible explanation for this disconnection between state and trait positive affect is the extent to which individuals with schizophrenia engage in elaborative processing of positive stimuli. To assess this, we examined evoked gamma band activity in response to positive words over several seconds in a group with schizophrenia, a group with major depressive disorder, and a healthy control group.

Prevalence and Specificity of the Abnormal Niacin Response: A Potential Endophenotype Marker in Schizophrenia.

The skin flush response to niacin is abnormally blunted among a subset of patients with schizophrenia (SZ), preferentially associates with SZ compared to other mental illnesses, occurs frequently in nonpsychotic members of SZ-affected families, appears heritable, and shows evidence of genetic association. The niacin response abnormality (NRA) may prove to be a useful SZ endophenotype. Using a laser Doppler flowmeter, we undertook this study to estimate the prevalence of NRA in SZ (n = 70), bipolar disorder (BP, n = 59), and healthy control (HC, n = 87) groups, and to estimate its specificity for the illness.

Pharmacological Isolation of Cognitive Components Influencing the Pupillary Light Reflex.

Cognitive operations can be detected by reduction of the pupillary light response. Neurophysiological pathways mediating this reduction have not been distinguished. We utilized selective blockade of pupillary sphincter or dilator muscles to isolate parasympathetic or sympathetic activity during cognition, without modifying central processes.

Associations between purine metabolites and clinical symptoms in schizophrenia.

Background: The antioxidant defense system, which is known to be dysregulated in schizophrenia, is closely linked to the dynamics of purine pathway. Thus, alterations in the homeostatic balance in the purine pathway may be involved in the pathophysiology of schizophrenia.

Methodology/principal Findings: Breakdown products in purine pathway were measured using high-pressure liquid chromatography coupled with a coulometric multi-electrode array system for 25 first-episode neuroleptic-naïve patients with schizophrenia at baseline and at 4-weeks following initiation of treatment with antipsychotic medication.

3-Hydroxykynurenine and clinical symptoms in first-episode neuroleptic-naive patients with schizophrenia.

One branch of the tryptophan catabolic cascade is the kynurenine pathway, which produces neurotoxic [3-hydroxykynurenine (3-OHKY), quinolinic acid] and neuroinhibitory (kynurenic acid) compounds. Kynurenic acid acts as a competitive antagonist at the glycine site of N-methyl-d-asparate receptors at high concentrations and as a non-competitive antagonist on the α7-nicotinic acetylcholine receptor at low concentrations. Kynurenine compounds also influence cognitive functions known to be disrupted in schizophrenia.

Reduction in perseverative errors with adjunctive ethyl-eicosapentaenoic acid in patients with schizophrenia: Preliminary study.

Introduction: Patients with schizophrenia have significant cognitive deficits, generally resistant to conventional treatment. This preliminary study examined the effects of ethyl-eicosapentanoate (EPA) on an executive function in early course patients.

Patients And Methods: Patients with schizophrenia were given, after an informed consent, 2 g of an EPA daily for 24 weeks, in an open-label study.

Cognition, dopamine and bioactive lipids in schizophrenia.

Schizophrenia is a remarkably complex disorder with a multitude of behavioral and biological perturbations. Cognitive deficits are a core feature of this disorder, and involve abnormalities across multiple domains, including memory, attention, and perception. The complexity of this debilitating illness has led to a view that the key to unraveling its pathophysiology lies in deconstructing the clinically-defined syndrome into pathophysiologically distinct intermediate phenotypes.

Sustained gamma-band EEG following negative words in depression and schizophrenia.

Introduction: Sustained and elaborative emotional information processing in depression and decreased affective elaboration in schizophrenia are considered hallmarks of these disorders but have not been directly measured. Gamma-band (35-45 Hz) EEG has been associated with semantic functions such as feature binding and may index these elaborative processing. This study examined whether there were group differences in baseline and sustained gamma-band EEG following emotional stimuli in healthy adults as well as adults with depression and schizophrenia.

Effects of word frequency on semantic memory in schizophrenia: electrophysiological evidence for a deficit in linguistic access.

Background: Abnormal storage and/or access are among the hypothesized causes of semantic memory deficit in schizophrenia. Neuropsychological and connectionist models have emphasized functional systems that serve the processing of word meaning and frequency: semantic storage disturbance is presumed to result from weak representations of word meaning; defective access is assumed to result from compromises to pathways that activate word frequency knowledge. Candidate biological systems include neuromodulatory pathways that normally function to enhance neural signals (e.

Semantic memory in schizophrenia: association with cell membrane essential fatty acids.

Introduction: Semantic memory and language deficits are associated with schizophrenia. Understanding how these systems operate in this disorder will likely require a multi-factorial model that explains their linkages with cognition and modulation by dopamine. A biological factor that may provide causal convergence for these connections is cell membrane composition and dynamics.

Language disorder in schizophrenia as a developmental learning disorder.

Receptive language disorder in schizophrenia is hypothesized to represent a learning disorder that involves a neurodevelopmental etiology. It is argued that a preexisting developmental language disorder may characterize a subset of schizophrenia patients. A primary deficit in the temporal dynamics of brain function is assumed to cause receptive language disorder in schizophrenia.

Sympathetic and parasympathetic innervation of pupillary dilation during sustained processing.

The contributions of separate sympathetic and parasympathetic pathways to pupillary dilation during a sustained processing task were studied through environmental and pharmacological manipulations. In Experiment 1, 22 healthy volunteers (11 female) performed a serial Subtract 7 task while pupil diameter was recorded both during moderate room light and in darkness. In a control for verbalization, subjects performed an easier Add 1 task.

Automatic activation of the semantic network in schizophrenia: evidence from event-related brain potentials.

Background: Language disorder associated with schizophrenia might be due to disturbances in both automatic activation and mechanisms of controlled attention. The contribution of each process to semantic memory dysfunction has not been determined for schizophrenia, and the semantic priming paradigm is well-suited for addressing this question. In the present report, event-related potentials (ERPs) elicited under conditions assumed to reveal automatic activation (short prime-target interval and low proportion of related words) are compared directly with ERPs elicited under conditions associated with controlled processing (long prime-target interval and high proportion of related words).

The relationship between membrane pathology and language disorder in schizophrenia.

Receptive language disorder in schizophrenia has been hypothesized to involve a fundamental deficit in the temporal (time-based) dynamics of brain function that includes disruptions to patterns of activation and synchronization. In this paper, candidate mechanisms and pathways that could account for this basic deficit are discussed. Parallels are identified between the patterns of language dysfunction observed for schizophrenia and dyslexia, two separate clinical disorders that may share a common abnormality in cell membrane phospholipids.

The language system in schizophrenia: effects of capacity and linguistic structure.

Dysfunction in receptive language processes has been reliably observed in individuals diagnosed with schizophrenia and their first degree family members. The present study addressed the unresolved issue of whether receptive syntax is intact in schizophrenia. The principal question concerned whether comprehension dysfunction in schizophrenia involves a disturbance in the processing of syntactic structure, a susceptibility to demands placed on temporal auditory processing, or some combination of these two general factors.

Neuropsychological assessment, depression, and past exposure to organic solvents.

This study assessed neuropsychological performance in persons with a history of exposure to organic solvents and nonexposed healthy controls. Structured clinical interviews were also done to determine current Axis I diagnosis of mood disorder to assess the contribution of mood disorder to neuropsychological performance. Solvent-exposed participants were found to have significantly reduced scores on 3 of 5 neuropsychological clusters (learning and memory, visuospatial, psychomotor speed) compared to controls.

Respiratory sinus arrhythmia in persons with organic solvent exposure: comparisons with anxiety patients and controls.

Persons exposed to organic solvents have psychiatric symptomatology and cognitive impairments. The results of several studies have suggested that some psychiatric symptoms in these patients reflect similar reactions observed in patients with anxiety disorders. Respiratory sinus arrhythmia provides an indication of impaired autonomic functioning.

Mood and behavioral symptoms in individuals with chronic solvent exposure.

Psychiatric symptoms have been reported for individuals who experience chronic exposure to low levels of organic solvents. However, it is not known what proportion of such individuals experience psychiatric disorder; which specific disorders may be characteristic of this population; or whether bioaccumulation of lead contributes to the relationship between solvent exposure and psychiatric symptoms. Twenty-nine male journeymen painters and 32 male non-painter control subjects were administered semi-structured diagnostic interviews for DSM-III-R Axis I and Axis II disorders.

Increased incidence of anxiety and depressive disorders in persons with organic solvent exposure.

Objective: The purpose of this study was to determine whether the prevalence of current and past DSM-IV axis I psychiatric disorders is higher among persons with a history of exposure to organic solvents than among a demographically similar group of nonexposed control subjects.

Methods: Thirty-eight solvent-exposed subjects and 39 nonexposed healthy control subjects were evaluated for axis I disorder with the Structured Clinical Interview for DSM-IV.

Results: A significantly higher number of solvent-exposed subjects (71%) met criteria for current DSM-IV axis I disorder in comparison with control subjects (10%).

Cognitive modulation of midbrain function: task-induced reduction of the pupillary light reflex.

The activation of processing resources has widespread effects in the nervous system. A model of pupillary control systems (Steinhauer S.R.

Modulation of language processing in schizophrenia: effects of context and haloperidol on the event-related potential.

Background: Disturbances in language associations were among the first clinical symptoms reported for individuals described as schizophrenic (Bleuler 1911/1950). Currently, associative language disturbance is a diagnostic feature of schizophrenia (American Psychiatric Association 1994); however, the mechanisms that produce this symptom remain unknown. In the present study, two candidate psychological functions were examined: sensitivity to semantic context and expectancy (attention).