[Neurobiology of obsessive-compulsive disorder]

Obsessive-compulsive disorder (OCD) is a frequent mental disorder that leads to an enormous impairment in the quality of life. Cognitive-behavioral explanatory approaches are well established. Scientific research on the underlying neurobiology has increased in recent years.

This article reviews current research findings and the etiopathophysiological considerations derived from them.

An overview of the genetic, epigenetic, structural, functional, and neurochemical alterations in OCD is presented. Additionally, the possible organic causes that can trigger obsessive-compulsive symptoms are summarized.

With respect to OCD a moderate heritability is assumed. On a molecular level, genetic variants and epigenetic variations in the serotonergic, dopaminergic and glutamatergic systems in particular seem to play a role in the pathogenesis of the disease and affect the corresponding neurotransmission. Cortico-striatal-thalamo-cortical loops are neurochemically modulated, and predominance of the activity of the direct excitatory pathway is hypothesized in OCD. Recent research also provides evidence for the involvement of frontoparietal and frontolimbic networks. Obsessive-compulsive symptoms may also have different organic (e.g., immunological) causes.

The neurobiology of OCD is partially understood and categorized in an integrative neurobiological model. For the rare secondary immunological causes the concept of "autoimmune OCD" has recently been proposed. The better understanding of the neurobiology of OCD might allow for individualized, personalized treatment approaches in the future.