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Decreased Callosal Thickness in Attention-Deficit/Hyperactivity Disorder.
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Decreased Callosal Thickness in Attention-Deficit/Hyperactivity Disorder.
Biol Psychiatry. 2008 Oct 6;
Authors: Luders E, Narr KL, Hamilton LS, Phillips OR, Thompson PM, Valle JS, Del'homme M, Strickland T, McCracken JT, Toga AW, Levitt JG
BACKGROUND: Neuroimaging studies of attention-deficit/hyperactivity disorder (ADHD) have revealed structural abnormalities in the brains of affected individuals. One of the most replicated alterations is a significantly smaller corpus callosum (CC), for which conflicting reports exist with respect to the affected callosal segments. METHODS: We applied novel surface-based geometrical modeling methods to establish the presence, direction, and exact location of callosal alterations in ADHD at high spatial resolution. For this purpose, we calculated the thickness of the CC at 100 equidistant midsagittal points in an age-matched male sample of 19 individuals with ADHD and 19 typically developing control subjects. RESULTS: In close agreement with many prior observations, the CC was shown to be significantly thinner in ADHD subjects in anterior and, particularly, posterior callosal sections. Covarying for intelligence did not significantly alter the observed ADHD effects. However, group differences were no longer present in anterior sections when covarying for brain volume and after excluding ADHD subjects comorbid for oppositional defiant disorder. CONCLUSIONS: Decreased callosal thickness may be associated with fewer fibers or a decrease in the myelination of fibers connecting the parietal and prefrontal cortices. This might affect interhemispheric communication channels that are necessary to sustain attention or motor control, thus contributing to symptoms of hyperactivity and impulsivity, or inattention, observed in ADHD. Future studies are necessary to determine whether callosal abnormalities reflect maturational delays or persist into adulthood.
PMID: 18842255 [PubMed - as supplied by publisher]
Oppositional defiant disorder.
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Oppositional defiant disorder.
Am Fam Physician. 2008 Oct 1;78(7):861-6
Authors: Hamilton SS, Armando J
Oppositional defiant disorder is defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., as a recurrent pattern of developmentally inappropriate, negativistic, defiant, and disobedient behavior toward authority figures. This behavior often appears in the preschool years, but initially it can be difficult to distinguish from developmentally appropriate, albeit troublesome, behavior. Children who develop a stable pattern of oppositional behavior during their preschool years are likely to go on to have oppositional defiant disorder during their elementary school years. Children with oppositional defiant disorder have substantially strained relationships with their parents, teachers, and peers, and have high rates of coexisting conditions such as attention-deficit/hyperactivity disorder and mood disorders. Children with oppositional defiant disorder are at greater risk of developing conduct disorder and antisocial personality disorder during adulthood. Psychological intervention with both parents and child can substantially improve short- and long-term outcomes. Research supports the effectiveness of parent training and collaborative problem solving. Collaborative problem solving is a psychological intervention that aims to develop a child's skills in tolerating frustration, being flexible, and avoiding emotional overreaction. When oppositional defiant disorder coexists with attention-deficit/hyperactivity disorder, stimulant therapy can reduce the symptoms of both disorders.
PMID: 18841736 [PubMed - in process]
