Abnormalities of Neurotransmission in Drug Addiction

Substance use disorders are prevalent and severe conditions associated with numerous health, social, and economic harms. While the neurobiological mechanisms are still not fully understood, adaptations in multiple neurotransmitter systems have been implicated in the development and maintenance of substance use disorders. The advent of molecular imaging techniques has provided a unique opportunity to better understand abnormalities of neurotransmission in humans with substance use disorders, and this insight may ultimately lead to improved treatment options in the future. This chapter provides a summary of positron emission tomography (PET) and single photon emission computed tomography (SPECT) studies in humans with alcohol, tobacco, cannabis, opioid, and stimulant use disorders. Studies to date provide consistent evidence that the dopaminergic system is disrupted in populations with substance use disorders, although there has been little research in other neurotransmitter systems and findings of existing studies have been mixed. Many PET and SPECT studies investigating abnormalities of neurotransmission in substance use disorder are limited by small sample sizes and over-reliance on male samples without comorbid conditions. In addition, the use of cross-sectional study designs does not make it possible to draw conclusions about causality