Cannabis Use Declines with Aerobic Exercise

Improvement in addiction treatment interventions in needed.  Many substance dependence individuals end up with with a chronic illness with frequent relapse following periods of abstinence.

Aerobic exercise appears to be a candidate for a treatment component in a variety of addictive disorders.  Aerobic exercise may produce a variety of changes in the brain that may influence craving and drug use.

Mechanisms induced by aerobic exercise that might influence drug craving and drug use include:

• Alteration in the brain reward circuit
• Increased release of brain dopamine and changes in dopamine receptor sensitivity
• Decrease in anxiety and depressive symptoms 

Maciej Bukowski and colleagues at Vanderbilt University recently published a trial of cannabis craving and use in a series of subjects.  Regular cannabis user were enrolled in a ten session intervention that included ten 30 minute supervised treadmill periods.  Subjects exercised at 60% of their calculated maximum heart rate. 

All subjects met DSM-IV criteria for cannabis dependence.  Subjects were not involved in any formal substance abuse treatment program and did not express a desire to reduce or discontinue their cannabis use.  Subjects were using an average of 33.5 standard joint equivalents of cannabis at the beginning of the study.  The average daily cannabis use of the subjects is displayed in the plot below taken from the manuscript:

The plot demonstrates a significant reduction in daily cannabis use during the active aerobic exercise period. Daily joint use dropped from approximately six joints per day to an average of about two to three joints per day during the exercise period.  Following completion of the exercise phase, daily joint use climbed up again approaching the run-period levels.

This study was not done in a treatment-seeking sample.  It is unclear whether a similar effect would be seen in treatment seeking samples.  The study did not include a control sample.  Nevertheless, this study should stimulate research in treatment samples.  It suggests that regular aerobic exercise may be a valuable component of treatment for cannabis dependence.  Extended aerobic exercise may be valuable in the longer term reduction of cannabis use in those with cannabis dependence.

Chemical model of tetrahydrocannabinol (the psychoactive substance in cannabis) from the Creative Commons file at Wikipedia authored by Ben Mills.

Cannabis use Creative Commons Attribution License plot from Plos One manuscript authored by Maciej Bukowski and colleagues referenced below.

Buchowski MS, Meade NN, Charboneau E, Park S, Dietrich MS, Cowan RL, & Martin PR (2011). Aerobic exercise training reduces cannabis craving and use in non-treatment seeking cannabis-dependent adults. PloS one, 6 (3) PMID: 21408154

Stressful Live Events and Suicide

The role of stressful life events in suicide attempts and completed suicides has been a key area of study in the epidemiology of mental disorders.  Although suicidal behavior often occurs in the context of acute and chronic stressor, this does not prove a causal link.  We all could probably report serious life stressors throughout out lives and these could be interpreted as a reason for suicidal behavior.  So these associations could simply be a coincidence and not have anything to do with suicidal behavior.

A recent analysis of the WHO (World Health Organization) World Mental Health Surveys attempts to shed some light on this issue.  This study focussed on traumatic life events, a subset of life stressors that are associated with the development of PTSD.  The traumatic events studied included:

1. natural and man-made disasters
2. combat, war and refugee experiences
3. sexual and interpersonal violence
4. witnessing or perpetrating violence
5. death or trauma to a loved one

These more serious stressful life events provide a opportunity focus on events everyone would agree as significant.  The authors then looked at five lifetime categories related to suicide:

1. suicide ideation
2. suicide attempt
3. suicide planning in those with ideation
4. suicide attempt in those with a suicide plan
5. suicide attempt in those without a plan

The most common traumatic events reported by respondents across the 20 country survey included: death of a loved one (30.5%), followed by witnessing violence (21.8%), interpersonal violence (18.8%), accidents (17.7%), exposure to war (16.2%) and trauma to a loved one (12.5%).

The authors of the study perform complex analysis of the individual and cumulative effects of traumatic events.  The key findings summarized by these analyses include:

• experiencing interpersonal or sexual violence appeared to have the strongest effect on suicidal ideation and suicide attempt
• suicidal ideation and attempts had a dose-response effect with traumatic experiences--the more number of experiences, the higher the risk although this effect plateaued after experiencing about 4 events
• traumatic effects had limited effect on the progression from suicidal ideation to a suicide attempt
• effects of traumatic events occurred across low-, middle- and high income countries
• it was estimated that elimination of traumatic life events could reduce population suicide ideation by 15% and suicide attempts by 22%

The study was not able to analyze the effect on the most important variable--completed suicide.  This would add significant weight to attributing a link between traumatic life events.  Nevertheless, this study provides additional insight into stressful life events and suicide ideation and plan.  Traumatic events appear to be important although playing a relatively minor role.  Presence of a serious mental disorder, i.e. major depression, bipolar disorder, substance abuse, schizophrenia, severe personality disorder continues to be the most important risk factor for suicide.

Photo of Baby Duck in Grass Courtesy of Yates Photography

Stein DJ, Chiu WT, Hwang I, Kessler RC, Sampson N, Alonso J, Borges G, Bromet E, Bruffaerts R, de Girolamo G, Florescu S, Gureje O, He Y, Kovess-Masfety V, Levinson D, Matschinger H, Mneimneh Z, Nakamura Y, Ormel J, Posada-Villa J, Sagar R, Scott KM, Tomov T, Viana MC, Williams DR, & Nock MK (2010). Cross-national analysis of the associations between traumatic events and suicidal behavior: findings from the WHO World Mental Health Surveys. PloS one, 5 (5) PMID: 20485530