Which concept refers to the need for markedly increased amounts of a substance to achieve desired effects?

The concept of tolerance refers to a physiological process in which an individual requires increasingly larger amounts of a substance to achieve the same effects that were once attained with smaller doses. This phenomenon occurs as the body adapts to the presence of the substance, leading to changes in brain chemistry and receptor sensitivity. As tolerance develops, individuals may find that the effects diminish over time, prompting them to consume more of the substance to attain the original desirable effects.

This mechanism is significant in understanding substance use disorders, as it can influence the progression of use and the risk of developing dependence or addiction. In contrast, dependence relates to the body’s adaptation to a substance, leading to withdrawal symptoms when it is not present, while addiction encompasses a broader range of behaviors associated with compulsive use, loss of control, and continued use despite negative consequences. Withdrawal describes the physical and psychological symptoms that occur when a person who is dependent on a substance reduces or stops intake. Therefore, tolerance specifically focuses on the increase in dosage necessary to achieve prior effects, making it the most accurate concept in this context.