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Kenneth S Kendler

Publications and source records attributed to Kenneth S Kendler.

98 records · Page 6Linked to original sources
PubMed2002

The structure of schizotypy: relationships between neurocognitive and personality disorder features in relatives of schizophrenic patients in the UCLA Family Study.

Schizotypal personality features and certain neurocognitive deficits have been shown to aggregate in the relatives of schizophrenic patients, supporting the view that both are likely to reflect genetic contributions to liability to schizophrenia. Within the relatives of schizophrenic patients, however, the interrelationships between these potential indicators of liability to schizophrenia are not well known. Using data from the UCLA Family Study, we examine the interrelationships between personality disorder symptoms and neurocognitive functioning in nonpsychotic first-degree relatives of schizophrenic patients. Factor analyses indicate that several dimensions of schizotypy can be identified. A neurocognitive dysfunction dimension includes loadings from measures of sequential visual conceptual tracking, rapid perceptual encoding and search, and focused, sustained attention as well as the rating of odd and eccentric behavior from schizotypal personality disorder. Other aspects of schizotypal personality disorder form separate positive schizotypy and negative schizotypy dimensions. These analyses support the view that schizotypy is multidimensional in relatives of schizophrenic patients and indicate that neurocognitive deficits in perception and attention are associated with particular schizotypal personality features.

Adolescent↗
PubMed2002

The etiology of phobias: an evaluation of the stress-diathesis model.

BACKGROUND: We evaluated for phobias the prediction of the stress-diathesis model that the magnitude of stress at onset is inversely proportional to the level of underlying diathesis. METHODS: In more than 7500 twins from a population-based registry, we assessed the personality trait of neuroticism--as an index of phobia-proneness--and the lifetime histories of 5 phobia subtypes (agoraphobia, social, animal, situational, and blood or injury) and their associated irrational fears. Interviewers classified the mode of acquisition of the fear in phobic twins into 5 possible categories: trauma to self (further divided by severity), observed trauma to others, observed fear in others, taught by others to be afraid, and no memory of how or why fear developed. Analyses were conducted by logistic regression and analysis of covariance. RESULTS: The mode of acquisition had moderate test-retest reliability and differed meaningfully across phobia subtypes. None of the 3 tests of the stress-diathesis model was confirmatory: (1) the risk of phobias was not elevated in co-twins of twins who had no memory of their mode of acquisition, (2) the risk of phobias was not decreased in co-twins of twins who had severe trauma to self, and (3) no significant relationship, in phobic twins, was found between levels of neuroticism and mode of acquisition. CONCLUSIONS: These results are inconsistent with the traditional etiologic theories for phobias, which assume conditioning or social transmission. However, they are compatible with nonassociative models, which postulate that the vulnerability to phobias is largely innate and does not arise directly from environmental experiences. The stress-diathesis model may not be an appropriate paradigm for phobic disorders.

Adult↗
PubMed2002

Medical and psychiatric morbidity in obese women with and without binge eating.

OBJECTIVE: To determine the prevalence of obesity and binge eating in a population-based sample of female twins and to examine whether the presence of binge eating was associated with a greater risk for medical and psychiatric disorders in obese women. METHOD: A population-based study of twins who were born between 1934 and 1971 and both members responded to a mailed questionnaire (individual response rate was conservatively estimated to be 64%). Data for the present study are from the first and third interview waves. In Wave 1 (1987-1989), we assessed 92% of the eligible individuals (N = 2,163), 90% face-to-face and the remainder by telephone. We assessed lifetime history of psychiatric disorders, major medical disorders, health limitations, health satisfaction, and an array of personality and attitudinal measures. RESULTS: Obese women with binge eating reported greater health dissatisfaction and higher rates of major medical disorders than obese women without binge eating. Binge eating was also associated with higher lifetime prevalence of major depression, panic disorder, phobias, and alcohol dependence. Obese women with binge eating scored higher on neuroticism and symptom scales measuring depression, anxiety/phobia, and neurovegetative symptoms (i.e., insomnia, agitation, retardation, and obsessive-compulsive traits). DISCUSSION: The presence of binge eating in obese women is a marker for greater medical and psychiatric morbidity.

Adult↗
PubMed2002

The subtypes of major depression in a twin registry.

OBJECTIVE: The subtypes of major depression (MD) remain incompletely understood. While there is consensus about the existence of MD with 'typical' vegetative features, further data are required to evaluate the existence of MD with atypical features. METHOD: Assessment of MD symptomatology in year prior to interview was available in 6846 individual twins from a population-based twin registry. The nine 'A' criteria for DSM-IV MD were unpacked so that the nature of sleep disturbance, appetite and weight changes, and motoric alterations were recorded. Latent class analysis was used to create an empirical typology of MD. RESULTS: Seven latent classes appeared to provide the best representation of the data. The most severe of these classes had interpretable profiles corresponding to typical MD, atypical MD, and 'minor' but seemingly important depressive states. These classes were generally more deviant than a comparison group for nearly all available validators. There tended to be a gradient with the typical class being most extreme, minor depressive classes the least extreme, and the atypical class having an intermediate position. CONCLUSIONS: Our findings support the existence of atypical depression as a phenomenological subtype of MD. Besides the differences in symptom patterns, there are many more similarities than differences across a range of external validators. Similar to other reports, we found evidence of the importance and morbidity of depressive symptomatology that does not meet the DSM-IV MD thresholds.

Adult↗
PubMed2002

Sex differences in the genetic and environmental influences on the development of antisocial behavior.

The present study uses a population-based sample of 6.806 adult twins from same-sex and opposite-sex twin pairs to examine sex differences in the underlying genetic and environmental architecture of the development of antisocial behavior (AB). Retrospective reports of AB during three different developmental periods were obtained: prior to age 15 years (childhood), age 15-17 years (adolescent), and age 18 years and older (adult). Structural equation modeling analyses revealed that there was no evidence for sex-specific genetic or sex-specific shared family environmental influences on the development of AB; that is, the types of genetic and environmental influence were similar for males and females. For both sexes, a model that allowed for genetic influences on adolescent and adult AB that were not shared with childhood AB fit better than a model with a single genetic factor. In contrast, shared environmental influences on adolescent and adult AB overlapped entirely with shared environmental influences on childhood AB. Genetic factors played a larger role in variation in childhood AB among females, whereas shared environmental factors played a larger role among males. However, heritability of AB increased from childhood to adolescence and adulthood for both sexes, and the magnitude of genetic and environmental influences on adolescent and adult AB was approximately equal across sex. We speculate that sex differences in timing of puberty may account for the earlier presence of genetic effects among females.

Adolescent↗
PubMed2002

Toward a comprehensive developmental model for major depression in women.

OBJECTIVE: Major depression is a multifactorial disorder with many etiologic variables that are interrelated through developmental pathways. The authors used structural equation modeling to generate a developmental model for the etiology of major depression in women. METHOD: Data from 1,942 adult female twins, interviewed up to four times over a 9-year period, were used to construct a developmental model to predict depressive episodes in the year before the most recent interview. Eighteen risk factors in five developmental tiers were considered: 1) childhood (genetic risk, disturbed family environment, childhood sexual abuse, and childhood parental loss), 2) early adolescence (neuroticism, self-esteem, and early-onset anxiety and conduct disorder), 3) late adolescence (educational attainment, lifetime traumas, social support, and substance misuse), 4) adulthood (history of divorce and past history of major depression), and 5) the last year (marital problems, difficulties, and stressful life events). RESULTS: The best fitting model included six correlations and 64 paths, provided an excellent fit to the data, and explained 52% of the variance in liability to episodes of major depression. The findings suggest that the development of risk for major depression in women results from three broad pathways reflecting internalizing symptoms, externalizing symptoms, and psychosocial adversity. CONCLUSIONS: Major depression is an etiologically complex disorder, the full understanding of which will require consideration of a broad array of risk factors from multiple domains. These results, while plausible, should be treated with caution because of problems with causal inference, retrospective recall bias, and the limitations of a purely additive statistical model.

Adult↗
PubMed2002

Gender differences in the symptoms of major depression in opposite-sex dizygotic twin pairs.

OBJECTIVE: Gender differences in the symptoms of major depression have received limited research attention. The aim of this study was to explore these differences in male-female twin pairs. METHOD: Telephone interviews were conducted to determine the lifetime history of major depression in 1,404 complete pairs of opposite-sex dizygotic twins identified through a population-based registry. From these, the authors selected 201 pairs in which both twins fulfilled the DSM-III-R criteria for lifetime major depression. Dichotomous symptom variables were analyzed by using McNemar's chi-square. For continuous variables, conditional logistic regression was used. RESULTS: Female twins reported experiencing significantly more fatigue, hypersomnia, and psychomotor retardation during the most severe major depressive episode, whereas male twins reported more insomnia and agitation. CONCLUSIONS: In this group of matched twins, gender differences in the symptoms of major depression were seen in the areas of sleep, psychomotor changes, and fatigue. Gender significantly modifies some clinical features of major depression.

Adolescent↗