Cannabis and anxiety: a critical review of the evidence.
BACKGROUND
Anxiety reactions and panic attacks are the acute symptoms most frequently associated with cannabis use. Understanding the relationship between cannabis and anxiety may clarify the mechanism of action of cannabis and the pathophysiology of anxiety. Aims of the present study were to review the nature of the relationship between cannabis use and anxiety, as well as the possible clinical, diagnostic and causal implications.


METHODS
Systematic review of the Medline, PsycLIT and EMBASE literature.


RESULTS
Frequent cannabis users consistently have a high prevalence of anxiety disorders and patients with anxiety disorders have relatively high rates of cannabis use. However, it is unclear if cannabis use increases the risk of developing long-lasting anxiety disorders. Many hypotheses have been proposed in an attempt to explain these relationships, including neurobiological, environmental and social influences.


CONCLUSIONS
The precise relationship between cannabis use and anxiety has yet to be established. Research is needed to fully clarify the mechanisms of such the association.
Crippa
José Alexandre
JA
Department of Neurosciences and Behavior, Division of Psychiatry, Ribeirão Preto School of Medicine, University of São Paulo (USP-RP) and INCT Translational Medicine, Brazil.
Zuardi
Antonio Waldo
AW
Martín-Santos
Rocio
R
Bhattacharyya
Sagnik
S
Atakan
Zerrin
Z
McGuire
Philip
P
Fusar-Poli
Paolo
P
D000818:Animals; D001007:Anxiety / Q000209:etiology*; D002188:Cannabis / Q000009:adverse effects*; D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D006801:Humans; D002189:Marijuana Abuse / Q000150:complications* / Q000453:epidemiology