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Comorbidity of mental disorders and substance use: a brief guide for the primary care clinician

6.6 Major clinical issues with anxiety disorders and stimulant (including methamphetamine) use

Table of contents

Anxiety is common amongst stimulant users.
MAO-Is (either irreversible or reversible) are contraindicated in people using amphetamines or MDMA due to risk of serotonin syndrome. Deaths have been associated with concurrent use of moclobemide and MDMA.
Individuals should be encouraged to reduce or cease stimulant use so that anxiety symptoms can be better evaluated. In many cases this will result in an overall reduction in anxiety symptoms.
CBT is also effective in reducing general symptoms of anxiety.
CBT that focuses on coping mechanisms will be most effective in situations where the individual has been using stimulants to self medicate and cope with social anxiety situations.

6.6.1 Effects of stimulants on anxiety disorders

Anxiety is common amongst stimulant users^{(11, 29, 43, 50, 53, 54, 56)}.
Anxiety also presents during withdrawal from stimulants⁽⁴⁶⁾.
The incidence of anxiety increases following stimulant use⁽⁵³⁾.
Anxiety and its severity is significantly associated with the extent of stimulant use, with higher stimulant use predicting greater severity of anxiety^{(50, 53, 55, 56)}.
Individuals with childhood anxiety may have increased tendency to use stimulants, in particular ecstasy⁽⁵⁵⁾.

MAO-Is (either irreversible or reversible) are contraindicated in people using amphetamines or MDMA due to risk of serotonin syndrome (Appendix 1). Deaths have been associated with concurrent use of moclobemide and MDMA^{xxx(181, 182)}.
Stimulant drugs are likely to exacerbate the effects of SSRI and SNRI antidepressants (and visa versa) and may result in serotonin syndrome (Appendix 1)^{x(127, 179, 180)}. Patients should be warned of signs of serotonin syndrome and be monitored.
Fluoxetine, norfluoxetine, paroxetine and sertraline are potential inhibitors of CYP 2D6 which metabolises MDMA and methamphetamine. This may result in elevated plasma concentrations leading to toxicity^x.

Due to the anxiety-provoking effect of stimulants and the relationship to heavy use, individuals should be encouraged to reduce or cease stimulant use so that anxiety symptoms can be better evaluated. In many cases this will result in an overall reduction in anxiety symptoms.
Treatment of acute anxiety associated with stimulant withdrawal can be treated with benzodiazepines. However, use should be minimised as those with substance use disorders are at a greater risk of misusing benzodiazepines⁽¹⁹⁶⁾.
CBT is also effective in reducing general symptoms of anxiety****^{(196, 202, 203)}.
CBT that focuses on coping mechanisms will be most effective in situations where the individual has been using stimulants to self medicate and cope with social anxiety situations.
Citalopram and sertraline have the least CYP mediated drug interactions; however, all SSRIs are potential precipitators of serotonin syndrome in people using stimulants.