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Biomedical subjects

Andrew Pickles

Publications and source records attributed to Andrew Pickles.

29 records · Page 2Linked to original sources
PubMed2004

Time trends in adolescent mental health.

BACKGROUND: Existing evidence points to a substantial rise in psychosocial disorders affecting young people over the past 50 years (Rutter & Smith, 1995). However, there are major methodological challenges in providing conclusive answers about secular changes in disorder. Comparisons of rates of disorder at different time points are often affected by changes in diagnostic criteria, differences in assessment methods, and changes in official reporting practices. Few studies have examined this issue using the same instruments at each time point. METHODS: The current study assessed the extent to which conduct, hyperactive and emotional problems have become more common over a 25-year period in three general population samples of UK adolescents. The samples used in this study were the adolescent sweeps of the National Child Development Study and the 1970 Birth Cohort Study, and the 1999 British Child and Adolescent Mental Health Survey. Comparable questionnaires were completed by parents of 15-16-year-olds at each time point (1974, 1986, and 1999). RESULTS AND CONCLUSIONS: Results showed a substantial increase in adolescent conduct problems over the 25-year study period that has affected males and females, all social classes and all family types. There was also evidence for a recent rise in emotional problems, but mixed evidence in relation to rates of hyperactive behaviour. Further analyses using longitudinal data from the first two cohorts showed that long-term outcomes for adolescents with conduct problems were closely similar. This provided evidence that observed trends were unaffected by possible changes in reporting thresholds.

Adolescent↗
PubMed2004

Predictors of antisocial personality. Continuities from childhood to adult life.

BACKGROUND: Antisocial behaviour in adult life has its roots in childhood. AIMS: To explore the independent and joint effects of childhood characteristics on the persistence of antisocial behaviour into adult life. METHOD: A clinical sample of twins who were systematically ascertained in childhood was followed up 10-25 years later. A total of 225 twins were interviewed regarding childhood and adult psychiatric disorder, psychosocial functioning, and psychosocial and cognitive risk factors. RESULTS: In univariate analyses, childhood hyperactivity and conduct disorder showed equally strong prediction of antisocial personality disorder (ASPD) and criminality in early and mid-adult life. Lower IQ and reading problems were most prominent in their relationships with childhood and adolescent antisocial behaviour. In multivariate modelling childhood conduct disorder and hyperactivity predicted adult ASPD even when intervening risk factors were accounted for. The number of hyperactive and conduct symptoms also predicted adult outcome. CONCLUSIONS: Childhood disruptive behaviour has powerful long-term effects on adult antisocial outcomes, which continue into middle adulthood. The importance of number of symptoms, the presence of disruptive disorder, and intermediate experiences highlight three areas where interventions might be targeted.

Adolescent↗
PubMed2004

Affective problems in adults with mild learning disability: the roles of social disadvantage and ill health.

Mild learning disability is associated with an increased risk of affective disorder. This study examines the extent to which adult socio-economic disadvantage and ill health contribute to this risk. Samples were drawn from the 1958 National Child Development Study. Relative to a comparison group, mild learning disability at age 11 was associated with elevated rates of depressive symptoms throughout adult life, and carried a six-fold risk of chronic depressed mood. The group difference in depressed mood at age 43 years was in large part mediated by variations in adult socio-economic disadvantage and ill health.

Adult↗
PubMed2003

Linkage analysis of cross-sectional and longitudinally derived phenotypic measures to identify loci influencing blood pressure.

BACKGROUND: The design of appropriate strategies to analyze and interpret linkage results for complex human diseases constitutes a challenge. Parameters such as power, definition of phenotype, and replicability have to be taken into account in order to reach meaningful conclusions. Incorporating data on repeated phenotypic measures may increase the power to detect linkage but requires sophisticated analysis methods. Using the simulated Genetic Analysis Workshop 13 data set, we have estimated a variety of systolic blood pressure (SBP) phenotypic measures and examined their performance with respect to consistency among replicates and to true and false positive linkage signals. RESULTS: The whole-genome scan conducted on a dichotomous hypertension phenotype indicated the involvement of few true loci with nominal significance and gave rise to a high rate of false positives. Analysis of a cross-sectional quantitative SBP measure performed better, although genome-wide significance was again not reached. Additional phenotypic measures were derived from the longitudinal data using random effects modelling for censored data with varying levels of covariate adjustment. These models provided evidence for significant linkage to most genes influencing SBP and produced few false positive results. Overall, replicability of results was poor for loci, representing weak effects. CONCLUSION: Longitudinally derived phenotypes performed better than cross-sectional measures in linkage analyses. Bearing in mind the sample design and size of these data, linkage results that fail to replicate should not be dismissed; instead, different lines of evidence derived from complementary analysis methods should be combined to prioritize follow up.

Adult Children↗
PubMed2003

Natural categories or fundamental dimensions: on carving nature at the joints and the rearticulation of psychopathology.

The question of whether to view psychopathology as categorical or dimensional continues to provoke debate. We review the many facets of this argument. These include the pragmatics of measurement; the needs of clinical practice; our ability to distinguish categories from dimensions empirically; methods of analysis appropriate to each and how they relate; and the potential theoretical biases associated with each approach. We conclude that much of the debate is misconceived in that we do not observe pathology directly; rather, we observe its properties. The same pathology can have some properties that are most easily understood using a dimensional conceptualization while at the same time having other properties that are best understood categorically. We suggest replacing Meehl's analogy involving qualitatively distinct species with an alternative analogy with the "duality" of light, a phenomenon with both wave- and particle-like properties.

Child↗
PubMed2003

Normal variation and abnormality: an empirical study of the liability distributions underlying depression and delinquency.

BACKGROUND: Scale scores in studies of emotional and behavioural problems often possess highly skewed distributions. The long upper tails of these distributions place a small proportion of the population at some distance from the main body of the distribution. This invites an interpretation of their forming an abnormal group, one that may be qualitatively distinct. METHODS: Item-response models were fitted to data on parent and self-rated depression and delinquency from four large samples of children or adolescents. RESULTS: We found that underlying liability distributions show very little or no evidence of non-normality. CONCLUSIONS: The results suggest that (i) the skewed nature of the scale scores may be largely measurement artefacts, (ii) the distributions provide no evidence of a qualitatively distinct process generating abnormality as compared to normal variation and (iii) for characterising the whole distribution, including normality and abnormality, the selection of items in typical current assessments of emotional and behavioural problems is not optimal.

Adolescent↗
PubMed2003

Major depression and associated impairment: same or different genetic and environmental risk factors?

OBJECTIVE: Impairment was added as a diagnostic criterion for many psychiatric disorders in DSM-IV. Does the addition of impairment influence only prevalence rates, or does it also introduce new etiological factors into psychiatric diagnoses? METHOD: A lifetime history of major depression and associated functional impairment was assessed by personal interview with 3,669 female and 4,377 male twins from the population-based Virginia Twin Registry. Structural equation modeling was used to estimate the correlation between risk factors for major depression and associated functional impairment. RESULTS: While the risk factors for major depression and associated functional impairment are substantially correlated, they are not identical. The most parsimonious model suggests that over a quarter of the variance in associated functional impairment is due to factors unrelated to risk for major depression. Of the variance unique to associated functional impairment, approximately one-third is familial. The relationship between associated functional impairment and major depression did not differ significantly between men and women. CONCLUSIONS: Risk factors for major depression and associated functional impairment are substantially but imperfectly correlated. The addition of associated functional impairment as a criterion for the diagnosis of major depression not only lowers prevalence estimates but also introduces a small set of new etiological factors into the diagnosis of major depression.

Activities of Daily Living↗
PubMed2002

Bulimic symptoms in the Virginia Twin Study of Adolescent Behavioral Development: correlates, comorbidity, and genetics.

BACKGROUND: This paper addresses bulimia symptoms in a large community sample of twins aged 8 to 17 years. We aim to identify environmental correlates of bulimia symptoms and relationships with other psychiatric disorder symptoms. The twin design allows examination of the structure of genetic and environmental effects. METHODS: DSM-IIIR bulimia symptoms and consequential impairment were measured by interview in the first wave of the Virginia Twin Study of Adolescent Behavioral Development. Comorbidity with other psychiatric symptoms and environmental correlates were examined and the relative contributions of genes and environment were assessed using structural equation modeling. RESULTS: An item-response theory model indicated that the range of bulimic symptoms represented a single underlying trait. Bulimia symptoms were more common in postmenarche girls and positively associated with body-mass index. Subdiagnostic symptomatology was associated with impairment in psychosocial functioning. Bulimia symptoms were strongly associated with other psychiatric disorders symptoms including anxiety and depression. Genetic model fitting identified strong additive genetic effects on the symptom score. Accounting for a potential violation of the equal environment assumption for identical and fraternal twins slightly reduced estimated genetic variance. CONCLUSIONS: The pattern of comorbidity suggests overlap between bulimia symptoms and those of internalizing disorders. Substantial genetic variance (44%) was evident in the most conservative model.

Adolescent↗
PubMed2002

Neuro-epileptic determinants of autism spectrum disorders in tuberous sclerosis complex.

Tuberous sclerosis is one of the few established medical causes of autism spectrum disorder and is a unique neurogenetic model for testing theories about the brain basis of the syndrome. We conducted a retrospective case study of the neuro-epileptic risk factors predisposing to autism spectrum disorder in individuals with tuberous sclerosis to test current neurobiological theories of autism spectrum disorder. We found that an autism spectrum disorder diagnosis was associated with the presence of cortical tubers in the temporal but not other lobes of the brain. Indeed, the presence of tubers in the temporal lobes appeared to be a necessary but not sufficient risk factor for the development of an autism spectrum disorder. However, contrary to the predictions of some theories, the location of tubers in specific regions of the temporal lobe, such as the superior temporal gyrus or the right temporal lobe, did not determine which individuals with temporal lobe tubers developed an autism spectrum disorder. Instead, outcome was associated with various indices of epileptic activity including evidence of temporal lobe epileptiform discharges on EEG, the age to onset of seizures in the first 3 years of life and a history of infantile spasms. The results indicated that individuals with tuberous sclerosis are at very high risk of developing an autism spectrum disorder when temporal lobe tubers are present and associated with temporal lobe epileptiform discharges and early-onset, persistent spasm-like seizures. These risk markers constitute useful clinical indicators of prognosis, but further research is required to identify the neurobiological mechanisms responsible for their association with outcome. Most especially, it will be important to test whether, as the findings suggest, there is a critical early stage of brain maturation during which temporal lobe epilepsy perturbs the development of brain systems that underpin 'social intelligence' and possibly other cognitive skills, thereby inducing an autism spectrum disorder.

Autistic Disorder↗
PubMed2002

The relationship between DSM-IV oppositional defiant disorder and conduct disorder: findings from the Great Smoky Mountains Study.

BACKGROUND: We examine models of the relationship between oppositional defiant disorder (ODD) and conduct disorder (CD) in a community sample. Particular attention is paid to the generalisability of findings based on clinic-referred boys. METHODS: The analyses were based on four waves of data from the Great Smoky Mountains Study covering children in the community aged 9-16 years. Child and parent reports of DSM-IV symptoms, diagnoses, and a range of family and environmental adversities were collected using the Child and Adolescent Psychiatric Assessment. RESULTS: Cross-sectional analyses indicated that CD and ODD largely shared similar correlates, although some aspects of parenting appeared more related to CD than ODD. This pattern was broadly similar in boys and girls. Longitudinal analyses confirmed that ODD was a strong risk factor for CD in boys and there was a suggestion that ODD was a stronger risk factor for CD than for other common disorders. Atypical family structure was an important factor in the transition between ODD and CD in boys. In girls ODD provided no increased risk for later CD but was associated with increased risk for continued ODD, depression, and anxiety. CONCLUSIONS: These results are more consistent with a developmental relationship between ODD and CD in boys than girls.

Adolescent↗