The relationship between bipolar disorder and cannabis use in daily life: an experience sampling study.
OBJECTIVE
Although cannabis use is common in bipolar disorder and may contribute to worse clinical outcomes, little is understood about the relationship between this drug and bipolar disorder over the course of daily life. The aim of study was to examine the effect of cannabis on affect and bipolar symptoms in a group of individuals with bipolar disorder.


METHODS
Twenty-four participants with bipolar disorder type I or type II completed diaries for 6 days using Experience Sampling Methodology to investigate the temporal associations between cannabis, affect and bipolar disorder symptoms.


RESULTS
The results indicated that higher levels of positive affect increase the odds of using cannabis (OR:1.25 ,CI:1.06-1.47, P=0.008). However, neither negative affect, manic nor depressive symptoms predicted the use of cannabis. Cannabis use was associated with subsequent increases in positive affect (β=0.35, CI:0.20-0.51, P=0.000), manic symptoms (β=0.20,CI:0.05-0.34, P=0.009) and depressive symptoms (β= 0.17,CI:0.04-0.29, P=0.008).


CONCLUSIONS
The findings indicate that cannabis use is associated with a number of subsequent psychological effects. However there was no evidence that individuals with BD were using cannabis to self-medicate minor fluctuations in negative affect or bipolar disorder symptoms over the course of daily life. The findings in relation to existing literature and clinical implications are discussed.
The Spectrum Centre for Mental Health Research, Division of Health Research Lancaster University, Lancaster, Lancashire, United Kingdom.
Elizabeth
E
Tyler
The Spectrum Centre for Mental Health Research, Division of Health Research Lancaster University, Lancaster, Lancashire, United Kingdom.
Steven
S
Jones
School of Psychological Sciences, University of Manchester, Manchester, United Kingdom.
Nancy
N
Black
Health Methodology Research Group, School of Community Based Medicine, University of Manchester, Manchester, United Kingdom.
Lesley-Anne
LA
Carter
School of Psychological Sciences, University of Manchester, Manchester, United Kingdom.
Christine
C
Barrowclough
D000328:Adult; D000339:Affect; D001714:Bipolar Disorder / Q000188:drug therapy / Q000453:epidemiology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000009:adverse effects*; D012494:Sampling Studies; D012649:Self Concept; D012651:Self Medication