Clifford Ca

Genetic and environmental influences on obsessional traits and symptoms

A biometrical genetic analysis was carried out on the response of 419 pairs of twins to the 42-item version of Leyton Obsessional Inventory. Just under half the variation in both the Obsessional Trait and Symptom Scales was due to heredity. Multivariate analysis revealed a genetic effect on the development of obsessional personality and also the transmission of a general tendency predisposing to neurotic breakdown. Although the influence of heredity was outweighed by that of the environment, the latter effect showed an absence of general factors and, in particular, of any noticeable effect from the common home environment.

Twin and adoption studies. How good is the evidence for a genetic role

Research into the possibility that heredity may influence drinking habits is still in its infancy, and the conclusions that can be reached from a number of the available twin and adoption studies are limited by their methodological deficiencies. Nevertheless, the balance of evidence suggests a modest genetic effect on both normal drinking and alcoholism in men, though similar evidence for women is so far lacking. Further studies are required to assess the significance of the genetic contribution, to elucidate exactly what is inherited, and to examine the nature of gene-environment interactions.

Alcohol use, smoking habits and the Junior Eysenck Personality Questionnaire in adolescent Australian twins

In 1988, questionnaires were received from 1,400 twin pairs (17% MZM, 23% MZF, 17% DZM, 19% DZF, 24% DZO) aged 11 to 18, registered with the Australian NHMRC Twin Registry. Twins reported independently on themselves and on the perceived behaviour of their parents, siblings and friends. For smoking and for drinking in the previous month, the prevalence was modelled as a logistic function of age, sex, perceived smoking or drinking behaviour of family and friends, and the Adult Eysenck Personality Questionnaire (AEPQ) scales. Strengths of association were: family behaviour, odds ratio (OR) Language: en

Innovations in the statistical analysis of twin studies.

Advances in computer technology have made possible a greater sophistication in the statistical analysis of pedigree data, however this is not necessarily manifest by fitting more comprehensive causative models. Planned twin and family studies measure numerous explanatory variables, including perhaps genetic and DNA marker information status on all pedigree members, and the cohabitation of all pairs of individuals. A statistical analysis should examine the contribution of these measured factors on individual means, and in explaining the variation and covariation between individuals, concurrently with the postulated effect of unmeasured factors such as polygenes. We present two models that meet this requirement: the Multivariate Normal Model for Pedigree Analysis for quantitative traits, and a Log-Linear Model for Binary Pedigree Data. For both models, important issues are examination of fit, detection of outlier pedigrees and outlier individuals, and critical examination of the model assumptions. Procedures for fulfilling these needs and examples of modelling are discussed.

Alcohol-related brain damage: the neuropsychological deficits and their implication for independent living

Alcohol related brain damage as seen in those with a long history of alcohol abuse at high levels is almost always accompanied by severe medical complications. However, more subtle neuropsychological impairment may be found in an individual who has almost no physical problems associated with alcohol abuse. The most common problems are short term memory loss, an inability to perform problem solving activities and difficulties with learning new skills. This has wide implications in an individual who needs to learn a new lifestyle which does not involve alcohol abuse. The neuropsychological deficits of alcohol abusers may be one reason why rehabilitation programmes for alcohol abusers are not very successful, since they rely heavily on the acquisition of new skills and styles of thinking.