OBJECTIVE: The purpose of this study was to assess heritability of activity, attention, and impulsivity by comparing young monozygotic (MZ) twins with dizygotic (DZ) twins using objective measures. METHOD: The OPTAx test is an infrared motion analysis to record the movement pattern during a continuous performance test. Seventeen MZ and 12 same sexed DZ twin pairs in the range of 6 to 12 years were tested. The zygosity was determined by DNA-fingerprinting. The measures under investigation were activity (microevents and spatial scaling), impulsivity (errors of commission), and attention (accuracy and variability). For statistical analyses, the classical model of Falconer and the ACE and ADE genetic model for twin data were applied in order to estimate the proportion of the variance in activity, impulsivity and attention that is due to genetic effects. RESULTS: The respective coefficients of intraclass correlations in MZ twins ranged between .35 and .65 whereas for DZ twins the correlations were between .12 and .88. The heritability estimates resulting from both models were about 30% for 4 of the 5 measures, but none of these was significantly different from 0. CONCLUSION: We found no significant influence of genetic factors for activity, attention, and impulsivity. The authors conclude that further investigation of heritability of ADHD is necessary using larger sample sizes and objective measures.
OBJECTIVE: The purpose of this study was to assess heritability of activity, attention, and impulsivity by comparing young monozygotic (MZ) twins with dizygotic (DZ) twins using objective measures. METHOD: The OPTAx test is an infrared motion analysis to record the movement pattern during a continuous performance test. Seventeen MZ and 12 same sexed DZ twin pairs in the range of 6 to 12 years were tested. The zygosity was determined by DNA-fingerprinting. The measures under investigation were activity (microevents and spatial scaling), impulsivity (errors of commission), and attention (accuracy and variability). For statistical analyses, the classical model of Falconer and the ACE and ADE genetic model for twin data were applied in order to estimate the proportion of the variance in activity, impulsivity and attention that is due to genetic effects. RESULTS: The respective coefficients of intraclass correlations in MZ twins ranged between .35 and .65 whereas for DZ twins the correlations were between .12 and .88. The heritability estimates resulting from both models were about 30% for 4 of the 5 measures, but none of these was significantly different from 0. CONCLUSION: We found no significant influence of genetic factors for activity, attention, and impulsivity. The authors conclude that further investigation of heritability of ADHD is necessary using larger sample sizes and objective measures.
Authors: Maria A I Aberg; Nancy L Pedersen; Kjell Torén; Magnus Svartengren; Björn Bäckstrand; Tommy Johnsson; Christiana M Cooper-Kuhn; N David Aberg; Michael Nilsson; H Georg Kuhn Journal: Proc Natl Acad Sci U S A Date: 2009-11-30 Impact factor: 11.205
Authors: Johannes Wrege; Andre Schmidt; Anna Walter; Renata Smieskova; Kerstin Bendfeldt; Ernst-Wilhelm Radue; Undine E Lang; Stefan Borgwardt Journal: Curr Pharm Des Date: 2014 Impact factor: 3.116
Authors: Fenghua Li; Yi Zheng; Stephanie D Smith; Frederick Shic; Christina C Moore; Xixi Zheng; Yanjie Qi; Zhengkui Liu; James F Leckman Journal: Child Adolesc Psychiatry Ment Health Date: 2016-12-12 Impact factor: 3.033