It's an interdisciplinary topic,
We have different conceptualisations of addiction (diagnosis, what addiction means),
We focus on psychological & neurobiological theories (neuroscience of addiction, psychopharmacology),
Then we'll think about individual differences & social environment (not everyones at risk for substance use, genes, personality, families, social environments all play a role),
How substances/addictions affect our other aspects of psychology (behaviour, cognition, motivation),
The issues of treatment (issues in diagnosing and treating addiction)