The neurobiological link between OCD and ADHD
ADHD Attention Deficit and Hyperactivity Disorders
Obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) are two of the most common neuropsychiatric diseases in paediatric populations. The high comorbidity of ADHD and OCD with each other, especially of ADHD in paediatric OCD, is well described. OCD and ADHD often follow a chronic course with persistent rates of at least 40-50 %. Family studies showed high heritability in ADHD and OCD, and some genetic findings showed similar variants for both disorders of the
... me pathogenetic mechanisms, whereas other genetic findings may differentiate between ADHD and OCD. Neuropsychological and neuroimaging studies suggest that partly similar executive functions are affected in both disorders. The deficits in the corresponding brain networks may be responsible for the perseverative, compulsive symptoms in OCD but also for the disinhibited and impulsive symptoms characterizing ADHD. This article reviews the current literature of neuroimaging, neurochemical circuitry, neuropsychological and genetic findings considering similarities as well as differences between OCD and ADHD. functional) Magnetic resonance imaging ACC Anterior cingulate cortex ADHD Attention deficit hyperactivity disorder ADORA2A Adenosine A2A receptor BDNF Brain derived neurotrophic factor cAMP Cyclic adenosine monophosphate COMT Catecholamine-O-methyltransferase CSF Cerebrospinal fluid CST Cortico-striato-thalamico-cortical DA Delay aversion DAT Dopamine transporter DAT1 (SLC6A3) Dopamine transporter gene DRD2 Dopamine receptor D2 DRD4 Dopamine receptor D4 EAAC1 Excitatory amino-acid transporter 1 EEG Electroencephalography ERN/Ne Error-related negativity ERP Event-related potentials GABA Gamma-aminobutyric acid GWAS Genome-wide association studies HTR2A Serotonin 2A receptor MAO-A Monoamine-oxidase-A MCPP M-chlorophenylpiperazine MEG Magnetoencephalography MPFC Medial prefrontal cortex Silvia Brem and Edna Grünblatt have contributed equally to the work.