What Does Substance Addiction Mean?

Symptoms of substance addiction generally fall into four categories: 

• Impaired control
  • Intense cravings or strong urges to use the substance
  • Failed attempts to cut down or stop using the substance 
• Social problems
  • Interpersonal problems such as with family members, friends, or co-workers
  • Major tasks at work, school, or home are not completed 
  • Social, work, or leisure activities are given up or cut back because of substance use
• Risky use
  • Substance is used in risky settings
  • Continued use of substance despite knowing harmful consequences
• Drug effects
  • Tolerance (needing larger amounts to get the same effect)
  • Withdrawal symptoms (different for each substance)

Substance addiction may be accompanied by other psychiatric disorders. 

People usually start using alcohol or drugs voluntarily, but repeated use causes brain changes that interfere with a person’s self-control and ability to stop taking the substance. Drugs affect the brain's “reward circuit,” causing euphoria and flooding the brain with the neurotransmitter dopamine. Surges of dopamine reinforce substance use behaviors, which cause people to repeat them.

Continued use of substances such as drugs or alcohol cause the brain to adapt by reducing the ability of cells in the reward circuit to respond to it, which results in a person needing larger amounts to get the same effect (called tolerance).