Family study of schizophrenia and personality

The effect of paternal age on offspring intelligence and personality when controlling for paternal trait level

Paternal age at conception has been found to predict the number of new genetic mutations. We examined the effect of father’s age at birth on offspring intelligence, head circumference and personality traits. Using the Minnesota Twin Family Study sample we tested paternal age effects while controlling for parents’ trait levels measured with the same precision as offspring’s. From evolutionary genetic considerations we predicted a negative effect of paternal age on offspring intelligence, but not on other traits. Controlling for parental intelligence (IQ) had the effect of turning an initially positive association non-significantly negative. We found paternal age effects on offspring IQ and Multidimensional Personality Questionnaire Absorption, but they were not robustly significant, nor replicable with additional covariates. No other noteworthy effects were found. Parents’ intelligence and personality correlated with their ages at twin birth, which may have obscured a small negative effect of advanced paternal age (<1% of variance explained) on intelligence. We discuss future avenues for studies of paternal age effects and suggest that stronger research designs are needed to rule out confounding factors involving birth order and the Flynn effect.

Personality and psychopathology

Personality and psychopathology are increasingly recognized as tightly linked domains of study, despite historical and theoretical divisions. In this paper, we discuss the history of these divisions, models of inter-relations between personality and psychopathology, and selected examples from the literature demonstrating personality/psychopathology inter-relations in clinical and community populations. We begin by summarizing how personality, temperament, and personality disorders are increasingly conceptualized as overlapping entities. We next address relationships between personality traits and common mental illnesses/symptoms (e.g. internalizing and externalizing problems). Then we discuss the various ways in which personality traits may relate to Axis I conditions causally, with methods for distinguishing between them. We conclude with a more in-depth example, relating personality traits to schizophrenia.

Children of parents with affective and nonaffective psychoses: a longitudinal study of behavior problems

OBJECTIVE

It is generally accepted that children of parents with schizophrenia or other forms of psychosis are at heightened risk for a range of behavioral problems. However, it remains unclear whether offspring of parents with different forms of psychosis (e.g., schizophrenia, other nonaffective psychoses, and affective psychoses) have distinct forms of behavioral problems (i.e., internalizing and externalizing).

METHOD

Behavioral observations of children of parents with psychosis (N=281) and parents without psychosis (N=185) were conducted at ages 4 and 7 years.

RESULTS

There were no significant differences between groups in behavior observed at age 4 years. At age 7 years, compared with children of unaffected parents, children of parents with psychosis had an adjusted odds ratio of 2.8 (95% CI=1.5-5.6) for externalizing problems, in particular for children of parents with schizophrenia (adjusted odds ratio=4.4; 95% CI=1.7-12.5). This increase in risk for externalizing problems was observed for female children only (adjusted odds ratio=8.1; 95% CI=2.5-26.3). In contrast, male children were at increased risk for internalizing problems (adjusted odds ratio=3.6; 95% CI=1.6-8.3).

CONCLUSIONS

Children of parents with various forms of psychosis are at risk for internalizing and externalizing problems by age 7 years. This risk varies by gender of the offspring. Implications for treatment of parents with psychotic disorders and high-risk children are discussed.

Affective traits in schizophrenia and schizotypy

This article reviews empirical studies of affective traits in individuals with schizophrenia spectrum disorders, population-based investigations of vulnerability to psychosis, and genetic and psychometric high-risk samples. The review focuses on studies that use self-report trait questionnaires to assess Negative Affectivity (NA) and Positive Affectivity (PA), which are conceptualized in contemporary models of personality as broad, temperamentally-based dispositions to experience corresponding emotional states. Individuals with schizophrenia report a pattern of stably elevated NA and low PA throughout the illness course. Among affected individuals, these traits are associated with variability in several clinically important features, including functional outcome, quality of life, and stress reactivity. Furthermore, evidence that elevated NA and low PA (particularly the facet of anhedonia) predict the development of psychosis and are detectable in high-risk samples suggests that these traits play a role in vulnerability to schizophrenia, though they are implicated in other forms of psychopathology as well. Results are discussed in terms of their implications for treatment, etiological models, and future research to advance the study of affective traits in schizophrenia and schizotypy.

Avoidant personality disorder is a separable schizophrenia-spectrum personality disorder even when controlling for the presence of paranoid and schizotypal personality disorders The UCLA family study

It is unresolved whether avoidant personality disorder (APD) is an independent schizophrenia (Sz)-spectrum personality disorder (PD). Some studies find APD and social anxiety symptoms (Sxs) to be separable dimensions of psychopathology in relatives (Rels) of schizophrenics while other studies find avoidant Sxs to be correlated with schizotypal and paranoid Sxs. Rates of APD among first-degree Rels of Sz probands, attention-deficit/hyperactivity disorder (ADHD) probands, and community control (CC) probands were examined. Further analyses examined rates when controlling for the presence of schizotypal (SPD) and paranoid (PPD) personality disorders, differences in APD Sxs between relative groups, and whether APD in Rels of Szs reflects a near miss for another Sz-spectrum PD. Three hundred sixty-two first-degree Rels of Sz probands, 201 relatives of ADHD probands, and 245 Rels of CC probands were interviewed for the presence of DSM-III-R Axis I and II disorders. Diagnoses, integrating family history, interview information, and medical records, were determined. APD occurred more frequently in Rels of Sz probands compared to CC probands (p<0.001) and also when controlling for SPD and PPD (p<0.005). Two Sxs of APD were most characteristic of the Rels of Sz probands: "avoids social or occupational activities..." and "exaggerates the potential difficulties..." 65% of the Rels of Sz probands who had diagnoses of APD were more than one criterion short of a DSM-III-R diagnosis of either SPD or PPD. This indicates that APD is a separate Sz-spectrum disorder, and not merely a sub-clinical form of SPD or PPD.