Which of the following is a sign of a substance use disorder?

Increased tolerance is a well-recognized sign of a substance use disorder. This concept refers to the phenomenon where an individual requires larger amounts of a substance to achieve the same effects that were previously experienced with smaller doses. Over time, as a person continues to use a substance, their body becomes accustomed to its presence, leading to a need for increased quantities to feel the desired effects. This can indicate a developing dependency and is a critical aspect of assessing substance use disorders.

The other options reflect positive changes or outcomes that are typically not associated with a substance use disorder. Improved social relationships, enhanced mood stability, and heightened focus on work suggest better emotional regulation and functioning, which are generally contrary to the impacts of substance abuse. In fact, substance use disorders often cause relationship difficulties, mood instability, and impaired work performance, demonstrating the negative consequences rather than improvements in these areas.