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Chapter 3
Retz W, Klein RG (eds): Attention-Deficit Hyperactivity Disorder (ADHD) in Adults.
Key Issues in Mental Health. Basel, Karger, 2010, vol 176, pp 58–77
Molecular Genetics of Attention-Deficit
Hyperactivity Disorder
Wolfgang Retza _ Christine Margarete Freitagb
aSaarland
University Hospital, Institute for Forensic Psychology and Psychiatry, Homburg/Saar, and bDepartment
of Child and Adolescent Psychiatry, Frankfurt University Hospital, Frankfurt, Germany
Abstract
Family, twin, and adoption studies support the notion that attention-deficit hyperactivity disorder
(ADHD) is a highly heritable disorder. Following from these quantitative genetic findings, numerous
molecular genetic associations and a few linkage studies have been performed during the last years.
Due to evidence from pharmacological, neuroimaging and animal studies, the majority of the candidate
genes studied have focused on various facets of the dopamine, norepinephrine, and serotonin
neurotransmitter systems. Meta-analyses and pooled data analyses have supported associations
between ADHD and polymorphisms in genes coding for the dopamine D4 and D5 receptors and the
dopamine and serotonin transporters, respectively. Linkage analyses give some additional support
for an involvement of the dopamine transporter (DAT1) gene in ADHD. Recent studies have started
to implicate environmental factors and comorbidity as well as endophenotypes of ADHD in molecular
genetic research in order to further elucidate the neurobiological basis of this disorder.
Copyright c 2010 S. Karger AG, Basel
Chapter 5
Retz W, Klein RG (eds): Attention-Deficit Hyperactivity Disorder (ADHD) in Adults.
Key Issues in Mental Health. Basel, Karger, 2010, vol 176, pp 88–104
Chapter 4
Retz W, Klein RG (eds): Attention-Deficit Hyperactivity Disorder (ADHD) in Adults.
Key Issues in Mental Health. Basel, Karger, 2010, vol 176, pp 78–87
Neurophysiology of Adult Attention-Deficit
Hyperactivity Disorder
Christina G. Baehne _ Andreas J. Fallgatter
Department of Psychiatry and Psychotherapy, University of Würzburg, Würzburg, Germany
Abstract
Electrophysiological studies in adult attention-deficit hyperactivity disorder (ADHD) patients are still
very sparse. Therefore, the first part of the chapter shortly reviews quantitative EEG (qEEG) as well as
event-related potential (ERP) studies in children with ADHD. Basically, ADHD children are characterized
by a slowing in their qEEG frequencies and by longer latencies and smaller amplitudes in some
(but not all) of the ERP components. Generally, neurophysiological impairments described in the few
studies on adult ADHD patients are very similar to those of children with ADHD, while others change
with age and, therefore, might present a developmental perspective. A promising approach for
future studies may be the search for distinct subtypes or endophenotypes in ADHD which can be
detected with the help of EEG parameters. This strategy may be useful for the development of more
individualized and efficient treatments. Copyright © 2010 S. Karger AG, Basel
Electrophysiology
Brain Imaging in Adult Attention-Deficit
Hyperactivity Disorder
Marc Schneidera _ Michael Röslerb _ Wolfgang Retzb
aGGZ
Noord- en Midden-Limburg, Venray, The Netherlands, and bNeurocentre, Saarland University Hospital,
Homburg/Saar, Germany
Abstract
This review provides an overview about recent findings in attention-deficit hyperactivity disorder
(ADHD) brain imaging. ADHD is understood as a developmental disorder and several studies have
addressed brain development in children and adolescents. The hallmarks of impairment of cerebral
processing in ADHD are executive dysfunctions (motor execution, inhibitory control, working memory),
as well as deficient attention processing. In adulthood, imaging studies have revealed disturbances
in the prefrontal cortex, and anterior cingulated cortex (dACC) which are involved in the
regulation of selective attention, executive control and decision-making. Dysfunction of basal ganglia
is also a consistent finding in ADHD from childhood to adulthood. These findings suggest a
persistent dysregulation of frontostriatal circuitries. The cerebellum, and its role in affect and
cognition,
is also persistently implicated in the pathology of ADHD. The cerebello-(thalamo-)striato-cortical
network includes different attention networks and executive control instances. It appears from
brain-imaging data in adults that the pathophysiological principles of ADHD do not profoundly
change from childhood and adolescence to adulthood, regardless of some changes in psychopathology.
The hypothesis of a neurodevelopmental disorder seems to be reinforced on the basis of
imaging data of the adults. Copyright © 2010 S. Karger AG, Basel