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Posttraumatic stress disorder (PTSD) and eating disorders (ED) frequently co-occur, but the mechanisms underlying this association remain unclear. EDs are characterized by features of maladaptive eating behaviors including disinhibited eating and cognitive dietary restraint. Identifying the genetic overlap between PTSD symptoms and maladaptive eating behaviors may elucidate biological mechanisms and potential treatment targets. A community sample of 400 same-sex twins (102 monozygotic and 98 dizygotic pairs) completed the PTSD Checklist-Civilian (PCL-C) for PTSD symptoms and the Three-Factor Eating Questionnaire-Reduced (TFEQ-R18) for eating behaviors (uncontrolled eating, emotional eating, and cognitive dietary restraint). We used biometric modeling to examine the genetic and environmental relationships between PCL-C and TFEQ-R18 total and subscales scores. Heritability was estimated at 48% for PTSD symptoms and 45% for eating behavior overall. Bivariate models revealed a significant genetic correlation between PTSD symptoms and eating behavior overall (rg =.34; CI:.07,.58) and Uncontrolled Eating (rg =.53; CI:.24,.84), and a significant environmental correlation between PTSD symptoms and Emotional Eating (re =.30; CI:.12,.45). These findings suggest the influence of common etiology. Future research and clinical efforts should focus on developing integrated treatments. [ABSTRACT FROM AUTHOR]

We used the community-based University of Washington Twin Registry to investigate the genetic association between circadian type and sleep duration. Habitual sleep duration was obtained by self-report and circadian type was measured using a reduced 5-item Horne-Östberg Morningness-Eveningness questionnaire. Univariate and bivariate genetic analyses were fit using structural equation models. We used multinomial logistic regression to examine the overall and within-pair effects of circadian type on sleep duration in total and monozygotic (MZ) restricted twin samples. We surveyed 1620 twins, mostly female (70%), from same-sex pairs (1098 monozygotic, 522 dizygotic) with a mean age of 36 years (SD = 15). Among all twins, 23% were habitual short (<7 h/night), 68% normal (7-8 h/night), and 9% long (≥9 h/night) sleepers. Overall, 33% were morning-type, 52% neither-type, and 15% evening-type. The heritability of sleep duration was 31% and 40% for circadian type (both P < 0.05). The bivariate analysis did not reveal shared genetic influences on circadian type and sleep duration. When analyzing twins as individuals, eveningness was associated with short and long sleep duration in the total ( P < 0.001) and MZ restricted ( P < 0.05) twin samples. These findings were attenuated in the within-pair analysis in both samples suggesting that familial factors, namely genetics and shared environment, are in the pathway of interest or confound the association between circadian type and sleep duration. Because both short and long sleep is associated with adverse health outcomes, our findings suggest circadian evening-type may represent an endophenotype for poor health. [ABSTRACT FROM AUTHOR]

The University of Washington Twin Registry is a community-based registry of twins identified from the Washington State Department of Licensing. A fortuitous quirk in the Washington State drivers' license and identification number assignment, and collaborative Washington State laws, permitted us to build a statewide registry. Since obtaining approval from the Washington State Attorney General, the Washington State Department of Licensing has provided us with information on over 26,000 newly licensed twins, and we continue to receive computerized records on approximately 80 new twins per week. The University of Washington Twin Registry is assembled by mailing each twin a recruitment packet that includes an information sheet, brochure, brief survey, and nominal gift. Once both members of a twin pair have completed the packet, the pair is enrolled in the registry. As of June 2006, 2287 adult twin pairs have enrolled in the registry; about one half of these are female-female pairs. Among all twins, the average age is 32 years. Based on self-report, 52% of twins are monozygotic, 42% are dizygotic, and zygosity on 6% cannot yet be determined. We also have instituted a clinical protocol for collecting additional data and DNA from all twins participating in research studies requiring an in-person visit. The registry has established policies and procedures to protect the confidentiality of twin data and guidelines for the use of the registry by investigators. Plans for the further growth of the University of Washington Twin Registry and its use are discussed. [ABSTRACT FROM AUTHOR]