Amphetamine psychosis and schizophrenia: A dual model

Several of the behavioral consequences of acute and chronic amphetamine treatment were evaluated and related to the underlying neurochemical correlates of drug treatment. It was suggested that decreased noradrenergic activity after long-term amphetamine treatment influences stimulus sampling, whereas enhanced dopaminergic activity is responsible for the progressive augmentation of stereotypy and self-stimulation behavior observed after long-term exposure to amphetamine. It was hypothesized that amphetamine-induced psychosis and the symptomatology associated with schizophrenia are related to alterations in both norepinephrine and dopamine activity.     

Amphetamine psychosis and schizophrenia: A dual model

Several of the behavioral consequences of acute and chronic amphetamine treatment were evaluated and related to the underlying neurochemical correlates of drug treatment. It was suggested that decreased noradrenergic activity after long-term amphetamine treatment influences stimulus sampling, whereas enhanced dopaminergic activity is responsible for the progressive augmentation of stereotypy and self-stimulation behavior observed after long-term exposure to amphetamine. It was hypothesized that amphetamine-induced psychosis and the symptomatology associated with schizophrenia are related to alterations in both norepinephrine and dopamine activity.     

Dissociation and social cognition in schizophrenia spectrum disorder

While there is emerging evidence that dissociation is linked with trauma history and possibly symptoms in schizophrenia, it remains unclear whether dissociation represents a symptom dimensions in its own right in schizophrenia and as such is uniquely related to other features of illness. To explore this issue the current study sought to find out whether dissociation was uniquely related to an index of social cognition closely linked to social functioning, namely affect recognition. We hypothesized that dissociation would be linked with affect recognition because symptoms of dissociation may uniquely disrupt processes which are expected to be needed for correctly recognizing emotions. The sample contained 49 participants diagnosed with a schizophrenia spectrum disorder who were in a non-acute phase of disorder. Participants were concurrently administered the Bell-Lysaker Emotion Recognition Task, the Dissociative Experiences Scale, the Post Traumatic Stress Disorder Checklist and the Positive and Negative Symptoms Scale. Stepwise linear regression analyses were performed in which dissociative symptoms were forced to enter after the other symptoms in order to predict deficits in affect recognition. These analyses revealed that greater levels of dissociative symptoms predicted poorer recognition of negative emotions over and above that of positive, negative, cognitive and PTSD symptoms. Results are consistent with the possibility that dissociation represents a unique dimension o f psychopathology in schizophrenia which may be linked to function.     

CSF kynurenic acid and suicide risk in schizophrenia spectrum psychosis

Relationships between concentrations of cerebrospinal fluid (CSF) kynurenic acid (KYNA) and suicidal behavior were evaluated in 59 patients with psychosis after 22 years of follow-up. Three patients died from suicide and nine patients had a history of attempted suicide. Patients with attempted suicide had significantly lower concentrations of CSF KYNA.     

Attempted suicide predicts suicide risk in schizophrenia spectrum psychosis

Background: People with schizophrenia have an increased risk of suicide and attempted suicide is suggested to be an important risk factor. Aim: Our objective was to assess the cumulative survival, predictive values and odds ratios of attempted suicide for suicide in a long-term cohort of patients with schizophrenia spectrum psychosis with and without previous attempted suicide. Method: Inpatients (n=224) hospitalized with schizophrenia spectrum psychosis were followed for a mean of 25 years. All patients were followed up for causes of death. Information on suicide attempt before the end of the observation period was retrieved from medical records. Results: Eight percent died by suicide during the follow-up. Eighteen percent of suicide attempters died by suicide. Two percent of non-attempters died by suicide. There was a strong association between previous suicide attempt and suicide in men and women. Odds ratio for attempters vs. non-attempters was 10. Suicide risk was almost three times higher in male than female suicide attempters. Conclusion: Previous attempted suicide is an important risk factor for suicide in both men and women with schizophrenia spectrum psychosis, particularly in male suicide attempters. The suicide risk remains high over a long period. Continuous assessment of risk factors and appropriate treatment are crucial for this patient group to prevent suicide.     

Delta-9-tetrahydrocannabinol effects in schizophrenia: implications for cognition, psychosis, and addiction.

BACKGROUND: Recent advances in the neurobiology of cannabinoids have renewed interest in the association between cannabis and psychotic disorders. METHODS: In a 3-day, double-blind, randomized, placebo-controlled study, the behavioral, cognitive, motor, and endocrine effects of 0 mg, 2.5 mg, and 5 mg intravenous Delta-9-tetrahydrocannabinol (Delta-9-THC) were characterized in 13 stable, antipsychotic-treated schizophrenia patients. These data were compared with effects in healthy subjects reported elsewhere. RESULTS: Delta-9-tetrahydrocannabinol transiently increased 1) learning and recall deficits; 2) positive, negative, and general schizophrenia symptoms; 3) perceptual alterations; 4) akathisia, rigidity, and dyskinesia; 5) deficits in vigilance; and 6) plasma prolactin and cortisol. Schizophrenia patients were more vulnerable to Delta-9-THC effects on recall relative to control subjects. There were no serious short- or long-term adverse events associated with study participation. CONCLUSIONS: Delta-9-tetrahydrocannabinol is associated with transient exacerbation in core psychotic and cognitive deficits in schizophrenia. These data do not provide a reason to explain why schizophrenia patients use or misuse cannabis. Furthermore, Delta-9-THC might differentially affect schizophrenia patients relative to control subjects. Finally, the enhanced sensitivity to the cognitive effects of Delta-9-THC warrants further study into whether brain cannabinoid receptor dysfunction contributes to the pathophysiology of the cognitive deficits associated with schizophrenia.     

Epilepsy, psychosis and schizophrenia

A connection between epilepsy, especially temporal lobe (psychomotor, limbic) epilepsy (TLE) and schizophrenia has been proposed by a number of investigators. The evidence both supporting and challenging this widespread idea is reviewed, and several hypotheses are considered that may account for the higher incidence of this form of epilepsy and of schizophrenic psychoses after adolescence.     

Associations of anhedonia and cognition in persons with schizophrenia spectrum disorders, their siblings, and controls

The aim of the current study was to investigate the levels of social and physical anhedonia, as measured with the Chapman Scales for social and physical anhedonia in groups of patients with schizophrenia spectrum psychosis (n = 91), their unaffected siblings (n = 105), and control subjects drawn from a general population (n = 67). The second aim was to explore the effect of physical and social anhedonia on neuropsychological variables. Subjects with schizophrenia spectrum disorder had significantly more anhedonia than population controls, but the unaffected siblings did not differ from controls. Subjects with schizophrenia spectrum disorders had generalized cognitive deficits. Unaffected sibling status predicted impairments in executive and performance speed measures. Elevated physical anhedonia associated with deficits in verbal functions, but this was not related to genetic liability to schizophrenia. In conclusion, social and physical anhedonia did not seem to mediate neuropsychological deficits of schizophrenia family members.     

Neural bases for impaired social cognition in schizophrenia and autism spectrum disorders

Schizophrenia and autism both feature significant impairments in social cognition and social functioning, but the specificity and mechanisms of these deficits remain unknown. Recent research suggests that social cognitive deficits in both disorders may arise from dysfunctions in the neural systems that underlie social cognition. We explored the neural activation of discrete brain regions implicated in social cognitive and face processing in schizophrenia subgroups and autism spectrum disorders during complex social judgments of faces. Twelve individuals with autism spectrum disorders (ASD), 12 paranoid individuals with schizophrenia (P-SCZ), 12 non-paranoid individuals with schizophrenia (NP-SCZ), and 12 non-clinical healthy controls participated in this cross sectional study. Neural activation, as indexed by blood oxygenation level dependent (BOLD) contrast, was measured in a priori regions of interest while individuals rated faces for trustworthiness. All groups showed significant activation of a social cognitive network including the amygdala, fusiform face area (FFA), superior temporal sulcus (STS), and ventrolateral prefrontal cortex (VLPFC) while completing a task of complex social cognition (i.e. trustworthiness judgments). ASD and P-SCZ individuals showed significantly reduced neural activation in the right amygdala, FFA, and left VLPFC as compared to controls and in the left VLPFC as compared to NP-SCZ individuals during this task. These findings lend support to models hypothesizing well-defined neural substrates of social cognition and suggest a specific neural mechanism that may underlie social cognitive impairments in both autism and paranoid schizophrenia.     

Psychopathology and cognition in schizophrenia spectrum disorders: the role of depressive symptoms.

The cognitive correlates of five symptom dimensions based on PANSS ratings were examined in a group of 50 recent onset psychotic patients, using both objective and subjective cognitive measures. We were particularly interested in the depression dimension, since it has not been studied extensively thus far. The depression dimension showed a high number of correlations with both objective and subjective cognitive measures, such as problems with simple and divided attention, psychomotor slowing and subjectively experienced distractibility, overload and diminished attentional control. The other dimensions, including negative symptoms, have less cognitive correlates. It is possible that previous studies based on a three-dimensional model confounded correlates of negative symptoms with correlates of depressive symptoms. The results of this study suggest the need for more research into the mechanisms underlying the relationship between depressive symptoms and cognitive functioning in schizophrenia, and that patients with depressive symptoms are less efficient in information processing, but can compensate by investing more mental effort. Because subjective cognitive measures were related to mental effort in previous research, they can be a useful tool in future research.     

Validation of the dimensions of psychosis instrument in Mexican patients with schizophrenia spectrum disorders

The objective was to determine the psychometric properties of the Dimensions of Psychosis Instrument (DIPI) in Mexican patients with schizophrenia spectrum disorders. One-hundred patients were recruited. Convergent and divergent validity were determined with the positive and negative scores of the Positive and Negative Syndrome Scale; a forced five-factor exploratory principal-components analysis with varimax rotation was developed. Total DIPI score shows an adequate convergent validity. The rotated principal component matrix accounted for 82.1% of the variance. Our study gives further support of the adequacy of the DIPI for the assessment of the five most common subjective experiences related to psychosis.     

Neuropsychological performance and spectrum personality traits in the relatives of patients with schizophrenia and affective psychosis

Neuropsychological deficits are found in both schizophrenic patients and their relatives, and some studies have shown similar, but less severe, deficits in affective psychotic patients and their relatives. We set out to establish: (a) whether schizophrenia spectrum personality traits are more common in the relatives of schizophrenic patients than, in the relatives of affective psychotic patients; and (b) what the relation is between spectrum personality traits and neuropsychological deficits in these relatives. Relatives were interviewed using the International Personality Disorder Examination (IPDE), and also completed the National Adult Reading Test (NART), the Trail Making Test (TMT; Parts A and B) and Thurstone's Verbal Fluency Test (TVFT). Spectrum personality traits were equally common in 129 relatives of schizophrenic patients and 106 relatives of affective psychotic patients, but the performance of the former group was inferior to that of the latter on the NART and the TVFT. Relatives with high paranoid traits had lower NART scores than relatives without such personality traits; similarly, those with high schizoid traits took longer to complete the TMT, part B, than those without such traits; and relatives with high schizotypal traits generated significantly fewer words on the TVFT than those without such traits. We conclude that relatives of schizophrenic and affective psychotic patients share a propensity to schizophrenia spectrum traits, but relatives of the former have poorer neuropsychological performance. Furthermore, there exists an association between neuropsychological deficits and spectrum traits in both groups of relatives; in particular those with high paranoid traits have lower IQ scores than their less paranoid counterparts.     

Homocysteine and cognition in first-episode psychosis patients

In the last years, there has been growing evidence linking elevated homocysteine levels with cognitive dysfunction in several neurological and neuropsychiatric diseases. The aim of the present study was to investigate the potential relationship between elevated homocysteine levels and cognitive deficits in first-episode psychosis patients. Plasma levels and cognitive performance of 139 patients and 99 healthy volunteers were compared. Patients were classified as elevated homocysteine (>90 percentile for controls) and normal and compared on 22 cognitive outcome measures grouped into cognitive domains known to be impaired in schizophrenia. Patients had a statistically significant increase in plasmatic homocysteine levels. In addition, they presented with significantly increased cognitive deficits. However, no relationship between homocysteine levels and cognitive impairment was detected. These results suggest the need for further studies to clarify the role of homocysteine in the etiology and prognosis of psychosis.     

Substance use and cognition in early psychosis

OBJECTIVE: To determine the relation between substance use and cognition in individuals experiencing their first episode of psychosis. DESIGN: Prospective cross-sectional and longitudinal study. SETTING: An Early Psychosis Treatment and Prevention Program, an outpatient clinic in a psychiatry department at a university-affiliated hospital. PARTICIPANTS: Individuals with a psychotic illness who were admitted to an Early Psychosis Program; 266 patients were assessed at initial presentation, 159 at 1 year and 90 at 2 years. Most were outpatients. MEASURES: The effects of substance use (alcohol, cannabis, hallucinogens, cocaine, stimulants) on cognition were assessed. Substance use was determined by DSM-IV criteria, and the Case Manager Rating Scale was used to determine the level of substance use. A comprehensive cognitive battery of tests was used, and the Positive and Negative Syndrome Scale for schizophrenia was administered to all subjects to determine levels of positive and negative symptoms. RESULTS: Overall, both cross-sectionally and longitudinally, there were no significant associations between cognitive functioning and the use of various substances. Substance use was associated with higher positive symptoms. CONCLUSIONS: Individuals with psychotic disorders who show mild-to-moderate abuse of substances, in particular alcohol and cannabis, do not exhibit more cognitive impairment than those who do not do use the substances. However, substance use may have other detrimental effects on the process of the psychotic illness.     

Follow-up study of hysterical psychosis, reactive/psychogenic psychosis, and schizophrenia

The present study was undertaken to learn more about the longer-term course of nonaffective functional psychoses, including hysterical psychosis. A group of 48 female patients diagnosed with hysterical psychosis, nonhysterical reactive/psychogenic psychosis, and schizophrenia at their first admission were reassessed after an average follow-up period of 11.6 years. Seventy-five percent were receiving outpatient treatment; less than half were on neuroleptics, and only 35% were rehospitalized. The patients suffered from a few, mostly unspecific, symptoms and were relatively well adjusted socially. No differences were found between original diagnostic categories regarding all variables studied. Hysterical psychosis does not appear to be a special clinical entity, distinguishable from other reactive/psychogenic psychoses in the short term and from other nonaffective functional psychoses in the longer term. The symptomatology and clinical presentation of nonaffective functional psychoses at first admission do not allow any prognostic longer-term forecast, and the initial differences between individual psychoses tend to disappear over time.