Final answer:
Some individuals who abuse certain substances may experience reverse tolerance, where they become more sensitized to the effects of the drug over time.
Step-by-step explanation:
Tolerance occurs when a drug user requires more and more of a given drug in order to experience the same effects of the drug. In the context of substance abuse, some individuals may experience reverse tolerance, where they become more sensitized to the effects of a drug over time, even with small amounts. This can happen with certain substances like alcohol, where repeated abuse can lead to increased sensitivity to its effects.