Substance abuse and schizophrenia: impediments to optimal care

With lifetime prevalence estimates of substance abuse among schizophrenics as high as 47.01%, there is an increasing awareness of the importance of this dual diagnosis and the global deficiencies in our knowledge about this comorbid condition. Patients with substance abuse disorders and schizophrenia are problematic from a clinical, economic, and health care systems perspective. The lack of systematic research into phenomenology, etiology, and treatment approaches (both psychotherapeutic and psychopharmacologic) has hindered the development of an adequate strategy to care for the needs of these patients. Thus, these patients place a significant burden on the mental health delivery system through chronic disability, social dysfunction, frequent rehospitalizations, and poor overall treatment compliance. The authors critically review the contemporary literature relevant to concurrent substance abuse and schizophrenia, highlight major deficiencies in our knowledge, and call for research to reduce the individual, economic, and social costs of this condition.     

Effect of amyloid peptides on the increase in TrkA receptor expression induced by nicotine in vitro and in vivo

The ability of nicotine to induce a cytoprotective or neuroprotective action occurs through several down-stream mechanisms. One possibility is that the drug increases the expression of tyrosine kinase A (TrkA) nerve growth factor (NGF) receptors. Certain β-amyloid peptides (e.g., Aβ1–42) have been shown to bind with high affinity to α7 nicotinic receptors and thus interfere with a potentially neurotrophic influence. Treatment of differentiated PC-12 cells with nicotine produced a concentration-dependent increase in cell-surface TrkA receptors that occurred concomitantly with cytoprotection. The effect of nicotine was blocked by either of the α7 receptor antagonists α-bungarotoxin (α-BTX) or methyllycaconatine. The cytoprotective action of nicotine also was inhibited by pretreatment with 10–100 nM Aβ1–42. Nicotine also was administered (four injections of 30 μg, spaced evenly over 24 h) to rats by direct injection into a lateral cerebral ventricle. Brain TrkA expression was increased significantly in hippocampus and entorhinal cortex (up to 32% above control), with no changes found in cerebral cortex or hypothalamus. The nicotine-induced increases in TrKA expression in hippocampus and entorhinal cortex were significantly inhibited by 10 μg α-BTX or by 10 nmol Aβ1–42. Therefore, physiologically relevant concentrations of Aβ1–42 can prevent nicotine-induced TrkA receptor expression in brain regions containing cholinergic neurons susceptible to the neurotoxicity associated with Alzheimer’s disease.     

Going, going, gone . . . ? Implicit and explicit tests of conceptual knowledge in a longitudinal study of semantic dementia

Patients suffering from semantic dementia provide important constraints on theories of the structure and organisation of semantic memory. In this article we report one such patient, AM, whose progressive deterioration of semantics enables us to address the much-debated issue of whether conceptual structure is hierarchically organised. The hierarchical account predicts that brain damage should impair lower levels of the hierarchy (property information) before affecting higher level (category) information (Warrington and Shallice, Q. J. Exp. Psychol. 1975, 27, 635–657). We evaluate this prediction by repeated testing of AM in two studies—a semantic priming task and a verification task—over an 18 month period, contrasting the progressive deterioration of properties (functional and perceptual) and category relations (category co-ordinates and category labels). Properties were preserved longer than category information, arguing against a hierarchical account of semantic memory. In addition, functional properties were most robust to brain damage, supporting our claim that functional information plays a special role in semantic representations (Durrant-Peatfield et al., Proc. 19th Ann. Conf. of the Cognitive Science Society. Erlbaum, Mahwah, NJ, 1997, pp. 193–198. Tyler et al., Cognitive Neuropsychol. 1997, 14, 511–545).     

Estimating IQ from Adaptive Behaviour Information in People with Moderate or Severe Intellectual Disability

It is often useful in studies of intellectual disability to be able to stratify the sample in terms of intellectual level. However, this information is sometimes difficult to obtain, and can involve a great deal of time if full IQ assessments are performed. This study explores the accuracy with which IQ scores can be projected by multiple regression from adaptive behaviour scores provided by informants. Fifty-one people with moderate, severe or profound intellectual disability received IQ assessments using the Kaufman Assessment Battery, and adaptive behaviour assessments using the Adaptive Behavior Scales (ABS). Ninety percent of projected estimates differed by less than 30% from that estimated by the K-ABC. Mean percentage divergence between actual and predicted estimates of IQ for the 51 cases for which all data were available was 15.0%. Limitations of the technique are discussed. The actual coefficients for calculating IQ are given in tabular form.     

Starch, gloves and extradural catheters

We have investigated contamination of extradural catheters during normal handling with starch powdered gloves. In the laboratory, extradural catheters were handled in sterile fields with both powdered and non-powdered gloves, simulating preparation for patient insertion. The catheters together with glove samples were then examined using a Zeiss 940 scanning electron microscope. Microscopy of samples revealed starch contamination of the catheters handled with powdered gloves, especially in the side hole areas. We conclude that extradural catheters may be contaminated easily by starch powder from surgical gloves. This powder may then be deposited into the extradural space. The effect of starch in the extradural space is not known but starch is known to cause inflammatory and granulomatous reactions in other parts of the body as well as being directly allergenic. Powder contamination of catheters may be avoided easily by the use of powder-free gloves and we feel that these should be used whenever possible.      

Outcomes of cardiopulmonary resuscitation in dialysis patients.

Patients with renal failure are believed to have a poor survival rate after cardiopulmonary resuscitation, but there is little specific information about the outcomes of cardiopulmonary resuscitation in dialysis patients. To be better able to inform dialysis patients and assist them in decision making about cardiopulmonary resuscitation, the eight-year experience with cardiopulmonary resuscitation in dialysis patients at a university dialysis program was analyzed and outcomes were compared with those of a control group of nondialysis patients undergoing cardiopulmonary resuscitation during the same time period in the same hospital. Of 221 dialysis patients experiencing cardiopulmonary arrest, 74 (34%) had CPR compared with 247 (21%) of 1,201 control patients (P = 0.0002). Six of 74 (8%; 95% confidence interval, 2 to 14%) dialysis patients survived to hospital discharge compared with 30 of 247 (12%; 95% confidence interval, 8 to 16%) control patients (P = not significant). At 6 months after CPR, 2 (3%) of 74 dialysis patients were still alive compared with 23 (9%) of 247 controls (P = 0.044); this difference was not explained by age or comorbid conditions. Twenty-one (78%) of the 27 successfully resuscitated dialysis patients died a mean of 4.4 days later; 95% were on mechanical ventilation in an intensive care unit at the time of death. It was concluded that cardiopulmonary resuscitation is a procedure that rarely results in extended survival for dialysis patients. In discussions about cardiopulmonary resuscitation with dialysis patients, nephrologists should provide this information.