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: PurposeChronic fatigue syndrome (CFS) is characterized by profound fatigue accompanied by disturbances of sleep, cognition, mood, and other symptoms. Our objective was to describe sleep architecture in CFS-discordant twin pairs.: MethodsWe conducted a co-twin control study of 22 pairs of monozygotic twins where one twin met criteria for CFS and the co-twin was healthy. Twins underwent two nights of polysomnography.: ResultsThe percentage of Stage 3 and REM sleep was greater among the CFS twins than their healthy co-twins (P≤.05 for both), but no other differences in sleep architecture including sleep latency, REM latency, and total sleep time were observed. Compared to their co-twins, CFS twins had higher values for the apnea–hypopnea index and apnea–hypopnea arousal index (P≤.05 for both).: ConclusionThese results do not provide strong evidence for a major role for abnormalities in sleep architecture in CFS. Respiration appears impaired in CFS, but these clinical abnormalities cannot alone account for the prominence of sleep complaints in this illness. The co-twin control methodology highlights the importance of selecting well-matched control subjects. [Copyright &y& Elsevier]

Objectives: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is characterized by pain and voiding symptoms in the absence of an obvious infection or other cause. CP/CPPS frequently occurs with non-urological chronic overlapping pain conditions (COPCs) of unknown etiology. We conducted a co-twin control study in men discordant for chronic prostatitis (CP), an overarching diagnosis of which approximately 90% is CP/CPPS. The primary aim was to investigate the contribution of familial factors, including shared genetic and common environmental factors, to the comorbidity of CP and COPCs.Methods: Data from 6824 male twins in the Vietnam Era Twin Registry were examined to evaluate the association between self-reported lifetime physician diagnosis of CP with COPCs including fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, temporomandibular disorder, tension headaches, and migraine headaches. Random effects logistic regression models were used and within-pair analyses evaluated confounding effects of familial factors on the associations.Results: There were significant associations between CP and all 6 examined COPCs. After adjusting for shared familial influences in within twin pair analyses, the associations for all COPCs diminished but remained significant. Familial confounding was strongest for the association of CP with fibromyalgia and temporomandibular disorder and smallest for irritable bowel syndrome.Conclusions: CP and COPCs are highly comorbid. These associations can be partially explained by familial factors. The mechanisms underlying these relationships are likely diverse and multifactorial. Future longitudinal research can help to further elucidate specific genetic and environmental mechanisms and determine potentially causal relationships between CP and its comorbidities. [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study examined if associations between body mass index (BMI) and mental and physical health were independent of genetic and familial factors. Method: Data from 2831 twins (66% female) were used in an epidemiological co-twin control design with measures of BMI and mental and physical health outcomes. Generalized estimating equation regressions assessed relationships between BMI and health outcomes controlling for interdependency among twins and demographics. Within-pair regression analyses examined the association of BMI with health outcomes controlling for genetic and familial influences. Results: Adjusted analyses with individual twins found associations in women between BMI and perceived stress (P=.01) and depression (P=.002), and the link between BMI and depression (P=.03) was significant in men. All physical health outcomes were significantly related to BMI. Once genetic and familial factors were taken into account, mental health outcomes were no longer significantly associated with BMI. BMI in women remained related to ratings of physical health (P=.01) and body pain (P=.004), independent of genetic and familial influences. Conclusion: These findings suggest that genetic and familial factors may account for the relationship between increased weight and poor mental health. [Copyright &y& Elsevier]

Abstract: We used a classical twin design and measures of neighborhood walkability and social deprivation, using each twin''s street address, to examine genetic and environmental influences on the residential location of 1389 same-sex pairs from a US community-based twin registry. Within-pair correlations and structural equation models estimated these influences on walkability among younger (ages 18–24.9) and older (ages 25+) twins. Adjusting for social deprivation, walkability of residential location was primarily influenced by common environment with lesser contributions of unique environment and genetic factors among younger twins, while unique environment most strongly influenced walkability, with small genetic and common environment effects, among older twins. Thus, minimal variance in walkability was explained by shared genetic effects in younger and older twins, and confirms the importance of environmental factors in walkability of residential locations. [Copyright &y& Elsevier]

Abstract: We studied whether self-reported intent to exert cognitive control over eating was associated with differences in brain response to food cues, independent of genetic background. Subjects were ten pairs of identical twins in which one twin was a restrained eater and the co-twin was unrestrained, as classified by the Herman and Polivy Restraint Scale. Before and after ingestion of a milkshake, we used functional magnetic resonance imaging to measure brain response to photographs of objects, “fattening” food, and “non-fattening” food. At baseline, restrained eaters had greater activation in the left amygdala and the right thalamus in response to fattening food cues than did their unrestrained co-twins. When restrained eaters drank a milkshake, activation in response to fattening food photographs decreased across multiple brain areas, whereas activation induced by non-fattening food photographs increased. As compared to their unrestrained co-twins, restrained eaters who drank a milkshake had greater decreases in activation by fattening food images in the left amygdala and occipital lobe, and greater increases in activation by non-fattening food images in the medial orbitofrontal cortex. Because of the discordant monozygotic twin study design, the findings provide a rigorous level of support for the hypothesis that adopting an intention to restrain eating alters brain response to food cues. [Copyright &y& Elsevier]

Abstract: Objective: Interstitial cystitis/painful bladder syndrome (IC/PBS) is a chronic pain condition with unclear underlying etiology. Our objectives were to determine whether psychological distress was higher in twins with urological symptoms commonly found in IC/PBS than in twins without, and if so, did familial influences contribute to this association. Method: Data from 1165 female twins in a community-based sample were used. Urological symptoms, symptoms of posttraumatic stress disorder (PTSD), depression, anxiety and perceived stress were assessed with standardized questionnaires. Generalized estimating equation (GEE) regression models were used to examine the relationship between psychological distress and urological symptoms. Results: Compared to unaffected twins, twins with urological symptoms were more likely to report PTSD symptoms (OR=3.9; 95% CI=2.6–5.8), depression (OR=3.1; 95% CI=2.0–5.0), anxiety (OR=3.4; 95% CI=2.3–5.2) and perceived stress (OR=3.2; 95% CI=2.1–4.9). After adjusting for familial influences, the within-pair effects remained significant for PTSD symptoms (OR=2.2; 95% CI=1.2–3.8) and perceived stress (OR=2.2; 95% CI=1.2–3.8). Conclusion: Familial influences partially explained the relationship between indicators of psychological distress and urological symptoms. Future research should examine shared environmental and genetic mechanisms that may further explain this relationship and improve diagnosis and treatment of this unexplained clinical condition. [Copyright &y& Elsevier]

Abstract: Objective: The purpose of the study was to evaluate quantitative sleep electroencephalogram (EEG) frequencies in monozygotic twins discordant for chronic fatigue syndrome. Methods: Thirteen pairs of female twins underwent polysomnography. During the first night, they adapted to the sleep laboratory, and during the second night, their baseline sleep was assessed. Visual stage scoring was conducted on sleep electroencephalographic records according to standard criteria, and power spectral analysis was used to quantify delta through beta frequency bands, processed in 6-s blocks. Data were averaged across sleep stage within each twin and coded for sleep stage and the presence or absence of chronic fatigue syndrome (CFS). A completely within-subjects repeated measure multivariate analysis of variance evaluated twin pairs by frequency band by sleep stage interactions and simple effects. The relationship between alpha and delta EEG was also assessed across twin pairs. Results: No significant differences in spectral power in any frequency band were found between those with CFS and their nonfatigued cotwins. Phasic alpha activity, coupled with delta was noted in five subjects with CFS but was also present in 4/5 healthy twins, indicating this finding likely reflects genetic influences on the sleep electroencephalogram rather than disease-specific sleep pathology. Conclusions: The genetic influences on sleep polysomnography and microarchitecture appear to be stronger than the disease influence of chronic fatigue syndrome, despite greater subjective sleep complaint among the CFS twins. EEG techniques that focus on short duration events or paradigms that probe sleep regulation may provide a better description of sleep abnormalities in CFS. [Copyright &y& Elsevier]