This chapter explores the mechanisms and consequences of maladaptive decision making, which encompasses choices that are suboptimal, impulsive, and/or excessively risky. It defines and differentiates these three patterns of impaired decision making, which underpin various psychiatric disorders. The core of the discussion focuses on the neurobiological underpinnings of these deficits, examining how optimal levels of catecholamines, serotonin, and acetylcholine are crucial for adaptive decision-making processes. Furthermore, this chapter systematically maps the neural circuitry involved in decision making, detailing the roles of the cortico-basal ganglia-thalamo-cortical (CBGTC) loop, the mesocorticolimbic pathway, and specialized cortical regions like the prefrontal and orbitofrontal cortex (PFC and OFC) in controlling complex choice behavior.