Showing papers by "Hospital for Sick Children published in 2001"

Comprehension skill, inference-making ability, and their relation to knowledge.

Abstract: In this study we investigated the relation between young children’s comprehension skill and inferencemaking ability using a procedure that controlled individual differences in general knowledge (Barnes & Dennis, 1998; Barnes, Dennis, & Haefele-Kalvaitis, 1996). A multiepisode story was read to the children, and their ability to make two types of inference was assessed: coherence inferences, which were essential for adequate comprehension of the text, and elaborative inferences, which enhanced the text representation but which were not crucial to understanding. There was a strong relation between comprehension skill and inference-making ability even when knowledge was equally available to all participants. Subsidiary analyses of the source of inference failures revealed different underlying sources of difficulty for good and poor comprehenders.

Astrocyte-specific Expression of Activated p21-ras Results in Malignant Astrocytoma Formation in a Transgenic Mouse Model of Human Gliomas

Abstract: Activation of the p21-ras signaling pathway from aberrantly expressed receptors promotes the growth of malignant human astrocytomas. We developed a transgenic mouse astrocytoma model using the glial fibrillary acidic protein (GFAP) promoter to express oncogenic V 12 Ha- ras , specifically in astrocytes. The development of GFAP-immunoreactive astrocytomas was directly proportional to the level of V 12 Ha- ras transgene expression. Chimeras expressing high levels of V 12 Ha- ras in astrocytes died from multifocal malignant astrocytomas within 2 weeks, whereas those with moderate levels went to germ-line transmission. Ninety-five percent of these mice died from solitary or multifocal low- and high-grade astrocytomas within 2–6 months. These transgenic astrocytomas are pathologically similar to human astrocytomas, with a high mitotic index, nuclear pleomorphism, infiltration, necrosis, and increased vascularity. Derivative astrocytoma cells are tumorigenic upon inoculation in another host. The transgenic astrocytomas exhibit additional molecular alterations associated with human astrocytomas, including a decreased or absent expression of p16, p19, and PTEN as well as overexpression of EGFR, MDM2, and CDK4. Cytogenetic analysis revealed consistent clonal aneuploidies of chromosomal regions syntenic with comparable loci altered in human astrocytomas. Therefore, this transgenic mouse astrocytoma model recapitulates many of the molecular histopathological and growth characteristics of human malignant astrocytomas in a reproducible, germ-line-transmitted, and high-penetrance manner.

Inferential language in high-function children with autism.

Abstract: Despite average verbal intelligence, high-function children with autism have social comprehension deficits that are expressed by how they use and understand language. In this paper, we explored the general hypothesis that high-function children with autism make some, but not all, of the pragmatic inferences necessary for successful communication, even when they have the ability to perform noninferential language tasks. We contrasted the ability of 8 high-function children with autism (each with Verbal IQ > 70) and typically developing children to use and understand: pragmatic inferences about given or presupposed knowledge in mental state words; pragmatic inferences about new or implied knowledge in mental state words; bridging inferences essential for coherence; elaborative inferences involved in enriching a communication by means of figurative language; and the intentional inferences involved in speech acts. High-function children with autism could define words and identify multiple meanings for ambiguous words. In understanding words for mental states, they made inferences from mental state verbs to given or presupposed knowledge. However, they failed to infer what mental state verbs implied in context; to make inferences about social scripts; to understand metaphor; and to produce speech acts, all of which are inferences that are the basis of successful social communication because they elaborate meaning or convey intentions.

Are you better? A qualitative study of the meaning of recovery

Abstract: Purpose Research into the meaning of illness has often focused on an individual's transition into a state of being ill, for example the adoption of a sick role The question “Are you better?” addresses the transition out of this state and is fundamental to the patient–clinician relationship, guiding decisions about treatment However, the question assumes that all patients have the same meaning for “being better” The purpose of this study was to explore the meaning of the concept of recovery (getting better) in a group of people with upper limb musculoskeletal disorders Methods Qualitative (grounded theory) methods were used Individual interviews were conducted with 24 workers with work-related musculoskeletal disorders of the upper limb The audiotaped interviews were transcribed and coded for content Categories were linked, comparisons made, and a theory built about how people respond to the question “Are you better?” Results The perception of “being better” is highly contextualized in the experience of the individual Being better is not only reflected in changes in the state of the disorder (resolution) but could be an adjustment of life to work around the disorder (readjustment) or an adaptation to living with the disorder (redefinition) The experience of the disorder can be influenced by factors such as the perceived legitimacy of the disorder, the comparators used to define health and illness, and coping styles, which in turn can influence being better Conclusion Two patients could mean very different things when saying that they are better Some may not actually have a change in disease state as measured by symptoms, impairments, or function

DSM‐IV Internal Construct Validity: When a Taxonomy Meets Data

Abstract: The use of DSM-IV based questionnaires in child psychopathology is on the increase. The internal construct validity of a DSM-IV based model of ADHD, CD, ODD, Generalised Anxiety, and Depression was investigated in 11 samples by confirmatory factor analysis. The factorial structure of these syndrome dimensions was supported by the data. However, the model did not meet absolute standards of good model fit. Two sources of error are discussed in detail: multidimensionality of syndrome scales, and the presence of many symptoms that are diagnostically ambiguous with regard to the targeted syndrome dimension. It is argued that measurement precision may be increased by more careful operationalisation of the symptoms in the questionnaire. Additional approaches towards improved conceptualisation of DSM-IV are briefly discussed. A sharper DSM-IV model may improve the accuracy of inferences based on scale scores and provide more precise research findings with regard to relations with variables external to the taxonomy.

Values of electroretinogram responses according to axial length.

Abstract: Accurate interpretation of electroretinograms (ERGs) requires knowledge of effects of axial myopia on ERG responses. Our purpose was to derive expected changes of ERG responses according to axial length, to stimulus conditions that conform to the International Society for Clinical Electrophysiology of Vision (ISCEV) Standard for Electroretinography. ERGs from 60 subjects were recorded. The subjects were assigned to one of three groups according to the level of myopia. Thirty-three subjects had high myopia (-6.00 D to -14.50 D; mean age, 31 years), eight had mild myopia (-3.00 D to -5.00; mean age, 28 years), and 19 had a small refractive error (+0.75 D to -2.75 D; mean age, 27 years). No subjects had myopic retinopathy. Stimulus-response curves were fitted to dark-adapted b-wave amplitudes and maximum amplitude and semi-saturation constants derived. Axial lengths, measured with A scan ultrasound, ranged from 22.2 mm to 30.0 mm. Analysis of variance and post hoc t-tests revealed significant difference between subjects with high myopia and subjects with small refractive error for ERG amplitude data. There were no significant differences between the three groups for implicit times, the ratio of b- to a-wave and semi-saturation constant. There is linear reduction in the logarithmic transform of ERG amplitude with increasing axial length, related more to axial length than refractive error. We provide relative slope and intercept values, allowing labs to derive expected ERG amplitudes according to axial length. These derivations are valid for persons with no retinopathy.

Congenital Heart Disease in Maternal Phenylketonuria: Report from the Maternal PKU Collaborative Study

Abstract: The frequency and types of congenital heart disease in offspring from pregnancies in women with hyperphenylalaninemia were examined in the international prospective Maternal Phenylketonuria Collaborative Study. Relationships of congenital heart disease in offspring to the basal blood phenylalanine level in the mother, metabolic control through diet during pregnancy, and phenylalanine hydroxylase mutations in mother and offspring were determined. The 416 offspring from 412 maternal phenylketonuria pregnancies that produced live births and 100 offspring from the 99 control pregnancies were included in this examination. Thirty-four of the 235 offspring (14%; 95% CI, 10.2 to 19.6%) from pregnancies in phenylketonuric women with a basal phenylalanine level > or = 900 microM (15 mg/dL) [normal blood phenylalanine 1800 microM (30 mg/dL) significantly increased the risk for bearing a child with congenital heart disease (p = 0.003). Phenylalanine hydroxylase mutations in the mothers and offspring did not have an independent relationship to congenital heart disease but were related through the basal maternal phenylalanine levels. The data in this study indicate that a basal maternal phenylalanine level of 900 microM may be a threshold for congenital heart disease, that women with the most severe degree of phenylketonuria are at highest risk for bearing such a child, and that prevention of the congenital heart disease requires initiation of the low phenylalanine diet before conception or early in pregnancy with metabolic control no later than the eighth gestational week.

Comparison of three outcomes instruments in children.

Abstract: SUMMARY The purpose of this study was to compare prospectively the distributions, validity, and discriminative ability of three pediatric outcome questionnaires. Consecutive patients completed the Activities Scales for Kids (ASK), the Child Health Questionnaire Parent Form (CHQ-PF-28), and the Pediatrics Outcomes Data Collection Instrument (PODCI). The scores of the three instruments were compared with each other and with parents' and clinicians' ratings. Of 210 patients, 166 (79%) completed the three questionnaires. The CHQ-PF-28 had a different distribution than the other two questionnaires and showed both floor and ceiling effects. The ASK and PODCI instruments were highly correlated and discriminated better than the CHQ-PF-28, with fewer floor and ceiling effects. Each questionnaire, however, seemed to be measuring slightly different things.

Three weeks of Kirschner wire fixation for displaced lateral condylar fractures of the humerus in children.

Abstract: The authors assessed whether a period of 3 weeks, rather than the commonly used 6 weeks, of smooth Kirschner wire fixation and cast immobilization of the elbow was sufficient to achieve union of displaced fractures of the lateral humeral condyle treated by open reduction. The authors found only one nonunion in a case series of 104 children treated with 3 weeks of fixation. Infections occurred in two children (2%). Late review of 63 children (61%) showed abnormalities of elbow shape in 28 (44%) and wide surgical scars in 43 (68%). The abnormalities of elbow shape were mainly due to overgrowth of the lateral humeral condyle, to the formation of excessive amounts of bone over the outer surface of the condyle, or both. The authors' findings indicate that a period of 3 weeks of smooth Kirschner wire fixation and elbow immobilization is sufficient to achieve healing in most displaced fractures of the lateral humeral condyle treated by open reduction. The findings also indicate that new strategies are needed to reduce the occurrence of overgrowth of the lateral condyle, excessive formation of bone over the condyle, and wide scars.

Type I Diabetes and Multiple Sclerosis Patients Target Islet Plus Central Nervous System Autoantigens; Nonimmunized Nonobese Diabetic Mice Can Develop Autoimmune Encephalitis

Abstract: Type I diabetes and multiple sclerosis (MS) are distinct autoimmune diseases where T cells target either islet or CNS self-proteins. Unexpectedly, we found that autoreactive T cells in diabetic patients, relatives with high diabetes risk, nonobese diabetic (NOD) mice, and MS patients routinely target classical islet as well as CNS autoantigens. The pathogenic potential of CNS autoreactivity was testable in NOD mice. Pertussis holotoxin, without additional Ags or adjuvants, allowed development of an NOD mouse-specific, autoimmune encephalitis with variable primary-progressive, monophasic, and relapsing-remitting courses. T cells from diabetic donors transferred CNS disease to pertussis toxin-pretreated NOD.scid mice, with accumulation of CD3/IFN-gamma transcripts in the brain. Diabetes and MS appear more closely related than previously perceived. NOD mouse-specific, autoimmune encephalitis provides a new MS model to identify factors that determine alternative disease outcomes in hosts with similar autoreactive T cell repertoires.

The Molecular Basis of X-Linked Spondyloepiphyseal Dysplasia Tarda

Abstract: The X-linked form of spondyloepiphyseal dysplasia tarda (SEDL), a radiologically distinct skeletal dysplasia affecting the vertebrae and epiphyses, is caused by mutations in the SEDL gene. To characterize the molecular basis for SEDL, we have identified the spectrum of SEDL mutations in 30 of 36 unrelated cases of X-linked SEDL ascertained from different ethnic populations. Twenty-one different disease-associated mutations now have been identified throughout the SEDL gene. These include nonsense mutations in exons 4 and 5, missense mutations in exons 4 and 6, small (2–7 bp) and large (>1 kb) deletions, insertions, and putative splicing errors, with one splicing error due to a complex deletion/insertion mutation. Eight different frameshift mutations lead to a premature termination of translation and account for >43% (13/30) of SEDL cases, with half of these (7/13) being due to dinucleotide deletions. Altogether, deletions account for 57% (17/30) of all known SEDL mutations. Four recurrent mutations (IVS3+5G→A, 157–158delAT, 191–192delTG, and 271–275delCAAGA) account for 43% (13/30) of confirmed SEDL cases. The results of haplotype analyses and the diverse ethnic origins of patients support recurrent mutations. Two patients with large deletions of SEDL exons were found, one with childhood onset of painful complications, the other relatively free of additional symptoms. However, we could not establish a clear genotype/phenotype correlation and therefore conclude that the complete unaltered SEDL-gene product is essential for normal bone growth. Molecular diagnosis can now be offered for presymptomatic testing of this disorder. Appropriate lifestyle decisions and, eventually, perhaps, specific SEDL therapies may ameliorate the prognosis of premature osteoarthritis and the need for hip arthroplasty.

Postmarketing surveillance for human teratogenicity: a model approach.

Abstract: Background Most congenital defects associated with prenatal exposures are notable for a pattern of major and minor malformations, rather than for a single major malformation. Thus, traditional epidemiological methods are not universally effective in identifying new teratogens. The purpose of this report is to outline a complementary approach that can be used in addition to other more established methods to provide the most comprehensive evaluation of prenatal exposures with respect to teratogenicity. Methods We describe a multicenter prospective cohort study design involving dysmorphological assessment of liveborn infants. This design uses the Organization of Teratology Information Services, a North American network of information providers who also collaborate for research purposes. Procedures for subject selection, methods for data collection, standard criteria for outcome classification, and the approach to analysis are detailed. Results The focused cohort study design allows for evaluation of a spectrum of adverse pregnancy outcomes ranging from spontaneous abortion to functional deficit. While sample sizes are typically inadequate to identify increased risks for single major malformations, the use of dysmorphological examinations to classify structural anomalies provides the unique advantage of screening for a pattern of malformation among exposed infants. Conclusions As the known human teratogens are generally associated with patterns of structural defects, it is only when studies of this type are used in combination with more traditional methods that we can achieve an acceptable level of confidence regarding the risk or safety of specific exposures during pregnancy. Teratology 64:252–261, 2001. © 2001 Wiley-Liss, Inc.

Disability and difference: balancing social and physical constructions

Abstract: The world of disability theory is currently divided between those who insist it reflects a physical fact affecting life quality and those who believe disability is defined by social prejudice. Despite a dialogue spanning bioethical, medical and social scientific literatures the differences between opposing views remains persistent. The result is similar to a figure-ground paradox in which one can see only part of a picture at any moment. This paper attempts to find areas of commonality between the opposing camps, and thus to rearrange the figures of the paradox at a fundamental level. The purpose is first to identify areas in which common ground can be achieved, and secondarily, to clarify the areas in which disagreement continues. While a general and unified theory of physical difference/disability is beyond the scope of this paper the result may advance that general goal.

Cross-cultural comparisons of health status in Canada using the Health Utilities Index.

Abstract: Objective. The purpose of this study was to examine the differences in health status, as measured by the Health Utilities Index (HUI), among seven cultural groups in Canada defined by place of birt...

Substance Use Disorders in Young Adults With and Without LD Predictive and Concurrent Relationships

Abstract: This article reports on young people with and without learning disabilities (LD) and substance use disorders (SUD). Participants were assessed for LD at ages 12 and 19 and for SUD and psychiatric disorders at age 19. Participants with LD at ages 12 and 19 were more likely to develop an SUD or a psychiatric disorder compared to participants without consistent LD. Participants with LD at age 19 were more likely to have a concurrent SUD or psychiatric disorder compared to those without LD at age 19, while participants with LD at age 12 showed only a trend toward increased rates of SUD at age 19 when compared to participants without LD at age 12. Participants with and without LD did not differ in substance use, consumption levels, or onset history. In a multivariate model, adolescent LD was associated with a three-fold increased risk for SUD after behavioral problems and family structure had entered the model. Although these results provide some support for the notion that adolescents with LD are at increased risk for SUD, LD also appears to confer a general risk for adverse outcomes.

Neurodevelopment of children exposed in utero to treatment of maternal malignancy.

Abstract: Cancer is the second most common cause of death during the reproductive years, complicating approximately 1/1000 pregnancies. The occurrence of cancer during gestation is likely to increase as a result of a woman's tendency to delay childbearing. Improved diagnostic techniques for malignancies increases detection of cancer during pregnancy. Malignant conditions during gestation are believed to be associated with an increase in poor perinatal and fetal outcomes that are often due to maternal treatment. Physicians should weigh the benefits of treatment against the risks of fetal exposure. To date, most reports have focused on morphologic observations made very close to the time of delivery with little data collected on children's long-term neurodevelopment following in utero exposure to malignancy and treatment. Because the brain differentiates throughout pregnancy and in early postnatal life, damage may occur even after first trimester exposure. The possible delayed effects of treatment on a child's neurological, intellectual and behavioural functioning have never been systematically evaluated. The goal of this report was to summarize all related issues into one review to facilitate both practitioners' and patients' access to known data on fetal risks and safety.

Impact of chronic hepatitis B and interferon-α therapy on growth of children

Abstract: Interferon-alpha (IFN) has been approved as treatment for children with chronic hepatitis B (CHB). The aims of this study were to assess the impact on children's growth of the disease itself and of IFN treatment. The growth of 142 children with CHB (70 IFN-treated, 72 untreated) was monitored for a minimum of one year. Regression analysis models were used to determine which of the variables most affected children's growth. After adjusting for racial differences, the population of 142 children with CHB had a mean baseline height for age percentile of 39 and a mean baseline weight for age percentile of 38, which were significantly different (P < 0.0001) from the 50th percentiles of their respective reference populations. The height for age Z score of untreated children was inversely correlated with serum hepatitis B virus DNA and aspartate aminotransferase levels, and the weight for age Z score was inversely correlated with serum hepatitis B virus DNA levels. While undergoing IFN therapy, children displayed a "U-shaped" growth pattern, such that height for age and weight for age Z scores at 3 or 6 months were lower than scores at baseline or 12 months. In this study the average child with CHB showed compromised growth even in the absence of IFN therapy. During IFN therapy, children's growth was temporarily disrupted.

Analysis of repeated failures or durations, with application to shunt failures for patients with paediatric hydrocephalus

Abstract: We consider studies involving the repeated occurrence of certain events, in which the emphasis is on the gaps or times between events. Interesting methodological issues arise in such situations, including the validity of semiparametric methods for multiplicative hazard-based models and the possibilities for marginal analysis of successive gap times. We discuss these and other points in conjunction with an examination of observational data on repeated shunt failures for a population of children with hydrocephalus.

A national network for the tele-education of Canadian residents in pediatric cardiology.

Abstract: A trial of 11 video-conferenced teaching sessions for residents in pediatric cardiology was performed by the 7 training programs in Canada in order to share expertise in specialized areas, to expose trainees to educational telemedicine, and to acquaint residents with other programs and personnel. Topics included cardiac pathology, arrhythmias, magnetic resonance imaging, fetal physiology, pulmonary hypertension, and cardiomyopathy. The sessions were evaluated by 93 residents by questionnaire for content and technology. Session content was highly rated. Videoconference picture quality was highly rated, but sound quality and visual aids were rated as neutral or unsatisfactory by a significant minority, related to problems with several early sessions, subsequently corrected. 60% of respondents rated the videoconferences as good as live presentations. Presenters were generally satisfied although they required some adjustments to videoconferencing. The average cost per session was $700 Canadian. Videoconferencing of resident educational sessions was generally well accepted by most presenters and residents, and the trial has formed the basis for a national network. Adequate organizational time, and careful attention to audiovisual needs, are most important. Videoconference guidelines are suggested for presenters based on this experience.

Utility of Brief Teacher Rating Scales to Identify Children with Educational Problems: Experience with an Australian Sample

Abstract: The study aimed to determine the utility of teacher ratings of children's behaviour, oral language, and literacy skills in identifying children with educational problems, and to examine the relationship between behaviour, oral language, and literacy skills. Teacher ratings were obtained for a cohort of Year 2 pupils (N = 129, mean age = 7.3 years, SD =.33) from five schools in Western Australia, using three brief screening questionnaires. To determine the sensitivity and specificity of the screening instruments in identifying children with educational problems as determined by psychometric criteria, direct psychometric assessment of oral language, vocabulary, reading, and spelling was conducted for a subset of the children. Teacher ratings of language, literacy, and behaviour correlated significantly with the standardised test scores. The screening instruments for language and literacy had reasonable sensitivity (74%) and specificity (92%), but a fairly high rate of false negatives (26%) and rela...

Drugs and Sexual Assault A Review

Abstract: Sexual assault by an acquaintance (date rape) among young women and adolescents is an increasing phenomenon. The use of drugs for the purpose of inducing amnesia and rapid sedation of the victim is becoming more common. The lay press and public Internet sites increasingly contain information regarding these date rape drugs. In contrast, there is very little information in the medical literature regarding this issue. The purpose of this article is to review the major drugs used as date rape drugs as well as to review the modalities of detection for these drugs.

Economic Evaluation of a New Acellular Vaccine for Pertussis in Canada

Abstract: Objective: Pertussis is a highly contagious infection affecting mainly children. Acellular pertussis vaccines were recently introduced in Canada based on evidence of improved safety and efficacy overwhole cell vaccines, the current standard of care. The following study reports the economic impact of replacing the whole cell vaccine (wP) by a new acellular vaccine (aP) in the Ontario pertussis immunisation programme. Design: For a hypothetical cohort of 100 000 children from birth to the age of 8 years, the costs and consequences of pertussis vaccination with either aP or wP were compared. A decision analytical modelwas constructed for vaccine delivery, treatment of pertussis cases and vaccine adverse events, with analyses from the viewpoints of the Ontario Ministry of Health and society. Main outcome measures and results: The main outcomes were expected number of pertussis cases, hospitalisations, and workdays lost by parents. Data on vaccine effectiveness, pertussis incidence, and other parameters used in the model were from published literature. Costs were discounted at 5%, and extensive sensitivity analyses were undertaken. Over 8 years, in a cohort of 100 000 children, the introduction of aP would prevent 10 500 cases of pertussis, avoiding 504 hospital admissions and 73 500 days of work absence. For Ontario, healthcare cost savings over the same period would amount to 275 585 Canadian dollars ($Can), and societal savings to $Can9 752 864 (1997values). Results were sensitive to both incidence of pertussis and vaccine efficacy. Conclusion: This study suggests that even though the new acellular vaccine has a higher acquisition cost than the currentwhole cell vaccine, its improved efficacy and safety result in overall cost savings.

Discontinuing antidepressants and benzodiazepines upon becoming pregnant. Beware of the risks of abrupt discontinuation.

Abstract: QUESTION: Two of my patients are planning to become pregnant. One is taking paroxetine and the other lorazepam. We have discussed what to do when they become pregnant and have decided they should stop taking these drugs as soon as pregnancy is confirmed. Is this the right decision? ANSWER: The decision to discontinue these drugs during pregnancy should be based on scientific evidence rather than "hearsay" that women should not take psychotropic medications during pregnancy. Recent epidemiologic studies have documented the relative safety of these drugs, so women should not feel compelled to stop taking them when they become pregnant. If, after receiving appropriate evidence-based information, a woman decides to stop taking the drugs, they should be gradually tapered off to avoid abrupt discontinuation syndrome.

Maternal obesity and risk of neural tube defects.

Abstract: QUESTION: One of my patients is taking olanzapine for schizophrenia. She has gained a lot of weight, which, I understand, often happens with some of the new atypical antipsychotics. Due to her weight gain, she failed to notice she had become pregnant. Is she at risk? ANSWER: Experience with olanzapine is relatively slight, but available prospective data do not show increased teratogenic risk. Adiposity, on the other hand, is associated with increased risk of neural tube defects. Only some of this risk can be reduced by folate supplementation.

Lack of efficacy of humidification in the treatment of croup: Why do physicians persist in using an unproven modality?

Abstract: Background: Humidification is a time-honoured therapy for childhood croup (acute laryngotracheobronchitis). Despite a paucity of evidence supporting its use, many physicians, nurses and parents still apply this treatment. Our objective was to summarize available evidence and assess the rationale for the ongoing use of humidity to treat childhood croup. Methods: Searches of both MEDLINE and the Cochrane Database were conducted for English-language original or review literature on the treatment of croup with humidity, for the years 1966-1999. Results: Only 2 published studies have attempted to evaluate humidification therapy for croup, and none has been published since 1984. There is no published evidence to support the commonly held empirical view that humidity helps alleviate the symptoms of childhood croup, and no understanding of which factors of moisture or temperature affect patient outcomes. Risks may include scalding and unnecessary discomfort. Interpretation: There is no strong evidence supporting the use of humidity in the treatment of croup. Although such treatment is still widely used, it is not without risk, and further trials are required to address its efficacy.

Effects of prenatal exposure to marijuana.

Abstract: QUESTION: I am treating a 27-year-old woman who is now in her 10th week of pregnancy. She smokes marijuana two to three times a week, but does not use other drugs. She also smokes 20 cigarettes a day. I am concerned about the effects of marijuana exposure on her baby. ANSWER: It is not always possible to isolate the effect of marijuana exposure from other possible confounders on pregnancy outcome. Although marijuana is not an established human teratogen, recent well conducted studies suggest it might have subtle negative effects on neurobehavioural outcomes, including sleep disturbances, impaired visual problem solving, hyperactivity, impassivity, inattention, and increased delinquency.