Brain-Behavior Relationships: Neural Mechanisms of Impulsivity and Compulsivity in Neuropsychiatric Disorders.

Impulsivity and compulsivity are multidimensional transdiagnostic constructs with relevance to neurocognitive and other neuropsychiatric disorders. Broadly, impulsivity is the tendency to react quickly, while compulsivity is the tendency to perform repetitive and contextually inappropriate behaviors. Multiple cortical and subcortical neural pathways, neurotransmitter systems, synaptic plasticity changes, genetic factors, and epigenetic interactions influence decision-making, reward processing, and cognitive control. In this narrative review, we discuss the neural circuitry and disease mechanisms implicated in impulsivity and compulsivity, including emerging evidence of the cerebellum's influence on traditional reward circuitry. We also discuss current and emerging treatments, including neuromodulation targeted to the relevant network abnormalities. This high-level overview of impulsivity and compulsivity from a neurobiological perspective highlights the importance of furthering the understanding of the neural components and circuitry involved. Greater insight into the dynamics that modulate impulsivity and compulsivity may inform new therapeutics.