Biomedical subjects

Chantal Mérette

Publications and source records attributed to Chantal Mérette.

9 recordsLinked to original sources

PubMed2007

Informative phenotypes for genetic studies of psychiatric disorders.

Despite its initial promise, there has been both progress and some set backs in genetic studies of the major psychiatric disorders of childhood and adulthood. Finding true susceptibility genes may be delayed because the most genetically informative phenotypes are not being used on a regular basis in linkage analysis and association studies. It is highly likely that using alternative phenotypes instead of DSM diagnostic categories will lead more rapid success in the search for these susceptibility genes. The objective of this paper is to describe the different types of informative phenotypes that can be employed in psychiatric genetic studies, to clarify their uses, to identify several methodologic issues the design and conduct of linkage and association studies that use alternative phenotypes and finally to suggest possible solutions to those difficulties. This is a conceptual review with a focus on methodological issues that may arise in psychiatric genetics and examples are taken from the literature on autism, schizophrenia, bipolar disorder, and alcoholism.

Diagnostic and Statistical Manual of Mental Disord↗

PubMed2004

A factor analysis of the Strauss and Carpenter revised outcome criteria scale: a validation of the French translation.

This article seeks to validate the French translation of the Strauss and Carpenter revised outcome criteria scale (SCOCS-R) through the study of its interrater reliability, its convergent validity, and its factor structure. Using a sample of 113 DSM-IV schizophrenic subjects, we assessed the interrater reliability of the SCOCS-R and its convergent validity with an already validated scale (Social and Occupational Functioning Assessment Scale). The factor structure of the SCOCS-R was assessed using a principal components analysis. Interrater reliability was excellent (ri > or = 0.88 for each of the individual items), and the convergent validity with the Social and Occupational Functioning Assessment Scale proved to be highly satisfactory (r = 0.89; p < .0001). Factor analyses yielded two factors corresponding to social functioning and professional functioning. These factors accounted for 78% of the variance of outcome. These results demonstrate the reliability and the validity of the French translation of the SCOCS-R. Moreover, the two dimensions yielded by our factor analysis add to the evidence of the multidimensional structure of outcome. This article supports the relevance of the SCOCS-R to assess the dimensions of outcome in schizophrenic subjects.

Diagnostic and Statistical Manual of Mental Disord↗

PubMed2003

A map of angular tuning preference in thalamic barreloids.

A double-labeling protocol was used to determine how cells with different angular preferences to whisker motion distribute across the dimensions of a barreloid in the ventral posterior medial nucleus of the rat thalamus. Individual barreloids were labeled retrogradely by injecting Fluoro-Gold in identified barrel columns, and single relay cells (n = 30) pertaining to the labeled barreloids were stained juxtacellularly with Neurobiotin after determination of their angular tuning preference to controlled whisker deflection. Results show that cells with like angular preference are clustered within the barreloids. Those best tuned to forward and upward directions are located principally in the dorsal sector of the barreloid, whereas those best tuned to backward and downward motion are located principally in the central and ventral sectors, respectively. The relationship between cell location and angular preference was assessed by regression, cluster, and discriminant analysis. Together, these tests indicate that barreloids contain a map of shifting angular preference that transposes along the length of a barreloid directional property imposed at the periphery by the circumferential distribution of receptors around the vibrissa follicles.

Action Potentials↗

PubMed2003

Fine motor dexterity is correlated to social functioning in schizophrenia.

OBJECTIVE: To identify neuropsychological domains, including fine motor dexterity, that are related to social functioning in schizophrenia. METHOD: Thirty-six DSM-IV schizophrenic subjects were assessed using the Purdue Pegboard test, the Modified Wisconsin Card Sorting test, the Tower of London, Schwartz' Reaction Time and Wechsler's Associate Learning and Digit Span tests. Social functioning was measured by the Social and Occupational Functional Assessment Scale. RESULTS: Univariate regression analyses showed that the Purdue Pegboard, the Modified Card Sorting test, the Tower of London and Wechsler's Associate Learning subtest were significantly linked to social functioning. The best fitting multivariate model to explain social functioning included fine motor dexterity and executive functioning. CONCLUSION: Various neuropsychological measures correlated to social functioning, the correlation involving fine motor dexterity being the strongest one. Future studies of the prediction of social functioning in schizophrenia should include fine motor dexterity.

Cognition Disorders↗

PubMed2003

A pilot neuropsychological study of Kraepelinian and non-Kraepelinian schizophrenia.

OBJECTIVE: This is the first study to report a direct comparison of neuropsychological performance in Kraepelinian vs. non-Kraepelinian schizophrenia (SZ). METHODS: 17 Kraepelinian and 19 non-Kraepelinian subjects were assessed on a neuropsychological battery including the Purdue Pegboard, Schwartz' Reaction Time task, the Modified Card Sorting Test, the Wechsler's Associate Learning Test and the Digit Span. RESULTS: Kraepelinian schizophrenia was characterized by more impaired performance on the Purdue Pegboard and the Card Sorting test. These differences remained significant when introducing, as covariates, the type of neuroleptic used, the use of anticholinergic medication, age and gender. Differences on the Reaction Time, the Associate Learning and the Digit Span tasks did not reach statistical significance. CONCLUSIONS: These results suggest that Kraepelinian schizophrenia is characterized by impaired performance on fine motor dexterity and executive functioning. These results further add to the evidence for the validity of the distinction between Kraepelinian and non-Kraepelinian schizophrenia as a strategy to better understand the factors influencing severity and/or outcome in schizophrenia.

Adult↗

PubMed2003

[Genetics of schizophrenia and bipolar disorder: recent success of linkage studies with evidence of specific and shared susceptibility loci].

Results claiming linkage on two chromosomes for schizophrenia (SZ) and bipolar affective disorder (BP) were prematurely published in Nature at the end of the '80s. This ended up into disappointment. The knowledge accumulated from the first generation of unsuccessful molecular genetics studies of SZ and BP provided a stronger basis for the following generation of linkage studies that are now yielding encouraging converging results. Hence, we report several genomics susceptibility loci for SZ and BP, some of them being probably shared by the two major psychiatric illnesses whereas others could be specific to each.

Bipolar Disorder↗

PubMed2002

Chromosome 1q12-q22 linkage results in eastern Québec families affected by schizophrenia.

An impressive LOD score of 6.5 has recently been reported for schizophrenia on chromosome 1q21-22 in large families from eastern Canada [Brzustowicz et al., 2000: Science 288:678-682]. We did not reproduce such a finding in large pedigrees of eastern Québec based on seven markers spanning the 1p13-1q22 region and using both the models and phenotypes of Brzustowicz et al. and those used in our ongoing genome scan in 21 large French Canadian families. There was no significant total LOD scores in that chromosomal region (a maximum of 0.57) either for schizophrenia or bipolar disorders, nor any signal in individual large pedigrees. However, the samples of Brzustowicz et al. and ours differed in terms of their origins, the latter being of French ancestry and the former of Celtic and German descent. Population difference, genetic heterogeneity, and differences in ascertainment might explain the lack of replication. The result reported by Brzustowicz et al. cannot be discarded and should probably be considered as a susceptibility locus for a subset of the schizophrenic population.

Adult↗

PubMed2002

Quantifying dimensions in autism: a factor-analytic study.

OBJECTIVE: The objective of this study was to determine whether the phenotypic variation in autism and the related pervasive developmental disorders (PDDs) is a unitary construct or whether it is composed of distinct dimensions of autistic symptoms and measures of level of functioning. METHOD: One hundred twenty-nine children with autism and other forms of PDD from two samples with different inclusion criteria were assessed with the Vineland Adaptive Behavior Scales to measure level of functioning and the Autism Diagnostic Interview to measure severity of autistic behaviors. A factor analysis with varimax rotation was performed on each sample, separately and combined. RESULTS: Two factors emerged; one representing autistic symptoms and another representing level of functioning. The factor structure was remarkably similar and robust to variations in ascertainment and inclusion criteria between the samples. The validity of the distinction was supported by differences between males and females on the symptom factor, but not on the level of functioning factor. IQ was modestly correlated with level of functioning, but not with symptoms. CONCLUSIONS: The phenotypic variation seen in autism/PDD is composed of at least two different dimensions of autistic symptoms and level of functioning. The implications of this dimensional heterogeneity for research, classification, and clinical practice are discussed.

Adolescent↗

PubMed2002

Evidence in an international sample of alcohol-dependent subjects of subgroups with specific symptom patterns of antisocial personality disorder.

BACKGROUND: An earlier latent class analysis (LCA) of the symptoms of antisocial personality disorder in alcohol-dependent subjects enrolled in the Montreal sample of the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence suggested a three-class qualitative solution. The present analysis of a larger, international WHO/ISBRA sample provides evidence of a four-class solution with expanded symptomatic differentiation. METHODS: An unrestricted LCA of 15 antisocial behaviors expressed after 15 years of age was performed in 465 males with DSM-IV diagnosis of alcohol dependence, from the Montreal center (n = 120, overlapping the previous LCA), Helsinki (n = 80), São Paolo (n = 145), Sapporo (n = 22), and Sydney (n = 98); subjects were of various races, were ascertained from various sources, and showed a wide range of social adjustment. RESULTS: Four latent classes that appeared to differ qualitatively were identified. For descriptive purposes, the classes are termed socially adjusted adults (SAA, n = 197), antisocial work-adjusted adults (AWAA, n = 126), antisocial work-maladjusted adults (AWMA, n = 120), and antisocial aggressive adults (AAA, n = 23). The AAA class had the earliest age of onset for alcohol dependence, which decreased across classes. Proportion of alcohol-dependent first-degree relatives was low in the SAA class (13.6%), moderate in the AWAA and the AWMA classes (20.8% and 18.7% respectively), and high in the AAA class (33.3%). CONCLUSIONS: It is unknown if and to what extent racial, cultural, and ascertainment heterogeneity between collaborating centers might have influenced these analyses. The results presented here show qualitative differences among antisocial alcohol-dependent individuals in job adjustment and aggressive behavior, but only the latter distinction was relevant to familial alcohol dependence. Moreover, both the aggressive class and socially adjusted class differed in familial loading for alcohol dependence from the remaining two antisocial classes. These data provide improved empirical support for qualitative differentiation of aggressive from nonaggressive antisocial alcohol-dependent individuals and might also have nosological implications for antisocial personality disorder.

Adolescent↗