What physiological phenomenon is indicative of Substance Dependence?

Physiologic tolerance or withdrawal is a hallmark of Substance Dependence because it demonstrates the body's adaptation to the substance being used. Tolerance occurs when a person needs an increased amount of the substance to achieve the desired effect, indicating that their body has become accustomed to its presence. Withdrawal symptoms arise when the substance is reduced or stopped, leading to physical or psychological issues, which further emphasizes the body's dependence on the substance for normal functioning.

This physiological response is fundamental in distinguishing substance dependence from substance use or abuse, as it reflects changes in the brain and body that result from prolonged exposure to the substance, establishing a pattern of compulsive use despite negative consequences. This sets apart physiological dependence from aspects like cravings, social interactions, or sleep difficulties, which, while relevant to substance use disorders, do not specifically point to physiological dependence marks like tolerance and withdrawal symptoms do.