Effects of asthma on stability of Wisconsin card sorting test measures*☆ A twin study

BACKGROUND： The four measures used to assess the stability of the Wisconsin card sorting test （WCST）, that is, the number of preservative errors, percentage of preservative errors, number of categories completed, and the number of trials to complete the first category, reflect the function of the frontal lobe.
OBJECTIVE： This study was designed to investigate the effects of asthma on the stability of WCST measurements through the use of a twin study, and to analyze whether egg-type difference exists.
DESIGN： A cohort study.
SETTING： Mental Health Center, the First Affiliated Hospital of Chongqing Medical University.
PARTICIPANTS： Fifty-nine pairs of twins, aged 6-16 years, were primarily selected from schools between August 2005 and February 2007 and the WCST and Zygosity identification test was applied. Twins with achromatopsia, severe upper limb diseases, somatic diseases, or mental disorders were excluded. According to disease history of asthmatic attack, children were assigned into asthma （n = 16） and non-asthma （n = 43） groups.
METHODS： Four WCST measurements were determined in the 59 pairs of twins, and egg-type differences were identified in conjunction.
RESULTS： All 59 pairs of twins were included in the final analysis. Among the pairs of twins, 28 （48.5 %） were monozygotic twins, and 31 （52%） were dizygotic twins. Among the monozygotic and dizygotic twins, the number of preservative errors and percentage of preservative errors were significantly higher in the asthma group than in the non-asthma group （P 〈 0.05）. However, there was no significant difference of each corresponding measure between the monozygotic and dizygotic twins （P 〉 0.05）.
CONCLUSION： Asthma may affect the stability of WCST measures, but egg-type differences do not exist.     

Maternal cardiovascular adaptations to twin pregnancy

Multiple pregnancy places increased demands on the maternal circulation. Maternal left ventricular size and performance were measured with M-mode echocardiography in women with twin pregnancy in the second and third trimesters, and the findings were compared to those in normal singleton pregnancies. As expected, cardiac output was greater during twin than during singleton pregnancy; however, end-diastolic ventricular dimension was not. Output was increased in twin pregnancy during the second and third trimesters by heart rate and also during the third trimester by stroke volume. Increased stroke volume was effected by increased shortening, thus strongly suggesting increased contractility. Increased maternal heart rate and contractility during multiple gestations suggest that cardiovascular reserve is reduced.     

Choledochal cyst in an identical twin

A 15-year-old girl underwent an excisional procedure for the treatment of a choledochal cyst with an anomalous pancreatobiliary junction. Her sister, an identical twin, was perfectly healthy without any abnormality in the hepatobiliary system as demonstrated by ultrasound, ERCP, and infusion cholangiography. Choledochal cysts and pancreatobiliary malunions are possibly caused by developmental accidents in early intrauterine life rather than by genetic factors, because of the rarity of familial development and lack of occurrence in both members of a pair of identical twins. Offprint requests to: N. Urushihara     

Twin Studies in Psychiatry and Psychology: Science or Pseudoscience?

Twin studies are frequently cited in support of the influence of genetic factors for a wide range of psychiatric conditions and psychological trait differences. The most common method, known as the classical twin method, compares the concordance rates or correlations of reared-together identical (MZ) vs. reared-together same-sex fraternal (DZ) twins. However, drawing genetic inferences from MZ–DZ comparisons is problematic due to methodological problems and questionable assumptions. It is argued that the main theoretical assumption of the twin method—known as the equal environment assumption—is not tenable. The twin method is therefore of doubtful value as an indicator of genetic influences. Studies of reared-apart twins are discussed, and it is noted that these studies are also vulnerable to methodological problems and environmental confounds. It is concluded that there is little reason to believe that twin studies provide evidence in favor of genetic influences on psychiatric disorders and human behavioral differences.     

Twin pregnancy: report of a case with 35 days between deliveries

A prolonged interval between the births of the first and second of twins is rare and only a few reports are found in the literature. This paper reports a patient with twins with an interval of 35 days between the births of the 2 infants, who, due to prematurity and complications, were both stillborn. Three months later the patient became pregnant again and after an uneventful pregnancy gave birth to a healthy baby. However, due to breech presentation an abdominal delivery was undertaken.     

Perioperative management of face-to-face craniopagus twins separation

Craniopagus conjoining represents a complex and challenging issue for neurosurgeons as well as for anesthesiologists. A rare face-to-face case of conjoined twins underwent surgical separation and presented peculiar differences compared with those already reported in the literature. Even in cases lacking large cerebrovascular sinus connections, the impending risk of large blood loss and hemorrhagic shock in the infant requires a high level of surveillance and the institution of invasive monitoring.     

The developmental association between eating disorders symptoms and symptoms of depression and anxiety in juvenile twin girls

OBJECTIVE: We investigated the role of genetic and environmental factors in the developmental association among symptoms of eating disorders, depression, and anxiety syndromes in 8-13-year-old and 14-17-year-old twin girls. METHODS: Multivariate genetic models were fitted to child-reported longitudinal symptom data gathered from clinical interview on 408 MZ and 198 DZ female twin pairs from the Virginia Twin Study of Adolescent Behavioural Development (VTSABD). RESULTS: Model-fitting revealed distinct etiological patterns underlying the association among symptoms of eating disorders, depression, overanxious disorder (OAD), and separation anxiety disorder (SAD) during the course of development: 1) a common genetic factor influencing liability to all symptoms - of early and later OAD, depression, SAD, and eating symptoms; 2) a distinct genetic factor specifically indexing liability to early eating disorders symptoms; 3) a shared environmental factor specifically influencing early depression and early eating disorders symptoms; and 4) a common environmental factor affecting liability to symptoms of later eating disorders and both early and later separation anxiety. CONCLUSIONS: These results suggest a pervasive genetic effect that influences liability to symptoms of over-anxiety, separation anxiety, depression, and eating disorder throughout development, a shared environmental influence on later adolescent eating problems and persistent separation anxiety, genetic influences specific to early eating disorders symptoms, and a shared environmental factor influencing symptoms of early eating and depression.     

Non-gated fetal MRI of umbilical blood flow in an acardiac twin

Currently, the standard method of diagnosis of twin reversed arterial perfusion (TRAP) sequence is ultrasound imaging. The use of MRI for flow visualization may be a useful adjunct to US imaging for assessing the presence of retrograde blood flow in the acardiac fetus and/or umbilical artery. The technical challenge in fetal MRI flow imaging, however, is that fetal electrocardiogram (ECG) monitoring required for flow imaging is currently unavailable in the MRI scanner. A non-gated MRI flow imaging technique that requires no ECG monitoring was developed using the t-test to detect blood flow in 20 slices of phase-contrast MRI images randomly scanned at the same location over multiple cardiac cycles. A feasibility study was performed in a 24-week acardiac twin that showed no umbilical flow sonographically. Non-gated MRI flow images clearly indicated the presence of blood flow in the umbilical artery to the acardiac twin; however, there was no blood flow beyond the abdomen. This study leads us to conjecture that non-gated MRI flow imaging is sensitive in detecting low-range blood flow velocity and can be an adjunct to Doppler US imaging.     

Neonatal mortality rates among growth-discordant twins, classified according to the birth weight of the smaller twin

OBJECTIVE: The purpose of this study was to evaluate neonatal mortality rates among discordant twins, classified according to the birth weight of the smaller twin. STUDY DESIGN: We compared neonatal mortality rates among three groups of discordant twins (>25%), distinguished by the birth weight of the smaller twin being <10th, 10th to 50th, or >50th percentile. RESULTS: Among the 10,683 pairs of twins who were studied, the respective proportions of the three groups were 62.4%, 32.9%, and 4.7%. The neonatal mortality rate was significantly higher among pairs in which the smaller twin weighed <10th birth weight percentile (29. vs 11.1 and 11 per 1000; odds ratio, 2.7; 95% CI, 1.3, 5.7). This difference results from the higher mortality rates among the smaller but not among the larger twins. CONCLUSION: Severely discordant twin pairs in whom the smaller twin is also small for gestational age are at an increased risk of neonatal death. Identification of this group is an imperative step in the management of birth weight discordance in twin gestations.     

Risk factors for adverse outcomes in spontaneous versus assisted conception twin pregnancies

OBJECTIVE: To evaluate risk factors for adverse outcomes in spontaneous vs. assisted conception twin pregnancies. DESIGN: Historical cohort study. SETTING: Four academic tertiary medical centers. PATIENT(S): Women with twin pregnancies, including 2,143 spontaneous and 424 assisted conception; 2,492 nonreduced and 75 reduced. INTERVENTION(S): None (observational). MAIN OUTCOME MEASURE(S): Preeclampsia, preterm premature rupture of membranes, birth <32 weeks and <30 weeks, low birth weight, very low birth weight, and slowed midgestation fetal growth (<10th percentile between 20 and 28 weeks). RESULT(S): Among nonreduced pregnancies, assisted conception was not significantly associated with any adverse outcomes; among nulliparas, the risk for preeclampsia was increased regardless of method of conception; among spontaneous conceptions, the risks for preterm premature rupture of membranes, low birth weight, very low birth weight, and slowed midgestation fetal growth were increased. Among all pregnancies, fetal reduction increased risks for birth <32 weeks and <30 weeks, low birth weight, very low birth weight, and slowed midgestation fetal growth. Among nulliparas with assisted conceptions, fetal reduction increased the risks for birth <30 weeks, very low birth weight, and slowed midgestation fetal growth. CONCLUSION(S): These findings indicate that in twin pregnancies, assisted conception is not a risk factor for adverse outcomes, but rather specific factors that are more common among these pregnancies, such as nulliparity and fetal reduction, increase risks.