How does tolerance differ from dependence in drug use?

Tolerance refers to a phenomenon where an individual requires increasing amounts of a drug to achieve the same effect due to repeated use. This occurs because the body adapts to the drug's presence, resulting in a diminished response to its effects over time. In this context, dependence can be understood as the physiological or psychological need for the drug, which often manifests as a compulsive behavior to seek the substance to avoid experiencing negative consequences.

When someone is dependent on a drug, they may experience withdrawal symptoms if they suddenly reduce or stop using it, indicating a change in their body's normal physical function due to the regular presence of the drug. This physiological adaptation signifies a reliance on the substance to function normally.

Therefore, the correct answer accurately captures the essential differences: tolerance is characterized by a reduced response requiring higher doses, while dependence reflects a physical or psychological need for the drug itself. This distinction is crucial in understanding how individuals interact with substances and the potential consequences of their use.