The relationship between anxiety disorders and substance misuse is intimate. Here we concentrate on alcohol, although for completeness we also briefly mention other substances taken for anxiety relief or that cause anxiety.

The term ‘misuse’ is important and should be qualified. Many people drink alcohol or take illicit drugs without any apparent consequences. Once this use becomes problematic, at any level of consumption, misuse is a more appropriate term.

Recent research exploring the molecular underpinning of anxiety disorders, together with advances in our understanding of how alcohol affects brain neurochemistry, can help to explain this intimate relationship. We review the evidence and how this can provide a framework for both diagnosis and management in a patient with comorbid anxiety and substance misuse. Few studies address the best way of treating patients with dual diagnosis but several drugs are licensed for the treatment of individual anxiety disorders and are likely to be helpful in combination with alcohol treatment strategies.

Until recently, anxiety was used as an umbrella term that spanned the spectrum from normal human emotion to severe pathological states. The 1970s and 1980s heralded the beginning of a more rigorous approach to the discrete constellation of symptoms that make up the individual anxiety disorders. This has not only helped in tailoring therapeutic approaches but has also enabled researchers to explore the pathophysiological foundations of the various disorders. The ICD–10 (World Health Organization, 1992) categorises anxiety disorders as phobic (social, simple, agoraphobic), generalised, panic disorder and obsessive–compulsive disorder (OCD). Of these, the last is less robustly associated with substance misuse.