Symptoms During Prophylaxis
If prophylactic exposure to the drug has been established, the clinician should confirm the presence of neuropsychiatric symptoms during the exposure. Particularly among veterans deploying to malaria-endemic combat areas, such symptoms may have occurred during a period of heightened stress coincident with their initial deployment, and the veterans may have misattributed these symptoms to nonmefloquine factors. The clinician should therefore take a careful history to identify specific symptoms listed in the mefloquine product documentation. Many AEs will commonly manifest following the first 3 doses, and the clinician may find that focusing on this period is useful.9
When mefloquine is used for prophylaxis, anxiety and depression each affect between 1% and 10% of users. Other AEs that may develop include panic attacks; severe mood swings; behavioral AEs, including agitation, aggression, restlessness, and mania; symptoms of psychosis, including paranoia, delusions, and hallucinations; dissociative symptoms, including depersonalization; suicidal ideation; and cognitive AEs, including confusion.
The common symptoms of insomnia and abnormal dreaming affect > 10% of users. Particularly if multiple symptoms occur or if any of these symptoms occur following or coincident with symptoms of disturbed sleep, these should be considered strong evidence of symptomatic exposure.4 Veterans who report a history of continued mefloquine use despite the onset of such symptoms may be at particularly increased risk of chronic AEs.
The clinician should consider as evidence of symptomatic exposure information provided by others, including reports of obvious signs of nightmares or psychosis affecting the veteran. Clinicians should be aware that confusion and other psychiatric AEs caused by mefloquine during prophylactic use may limit the validity of self-reported history. Similarly, a history of seizure with mefloquine use or of the development of specific neurologic symptoms, particularly visual disturbances, dizziness, vertigo, disequilibrium, and paresthesias, also should be considered strong evidence of symptomatic exposure and indication of an increased risk of chronic psychiatric AEs.4
Posttreatment Adverse Effects
Although chronic psychiatric AEs following malaria infection have long been attributed to cerebral involvement, recognition that mefloquine may independently cause chronic neuropsychiatric AEs may require that individual cases be reexamined to properly assign causation.10 Particularly in uncomplicated cases of malaria, neuropsychiatric symptoms that develop only after treatment with mefloquine should be considered plausibly to be due to the drug and as evidence of symptomatic exposure.
As with use of mefloquine in prophylaxis, these neuropsychiatric symptoms may evolve in the weeks to months following exposure. They also may contribute to lasting and significant changes in personality, mood, cognition, thought, sleep, and behavior.6
Conclusion
Chronic AEs from mefloquine may provide a parsimonious explanation for the onset and persistence of a veteran’s psychiatric symptoms, particularly in cases where these may have failed to respond to treatment. Clinicians evaluating veterans who are seeking care for lasting psychiatric symptoms should ensure that they screen for prior symptomatic mefloquine exposure. As recognition grows of the drug’s chronic AEs, symptomatic mefloquine exposure is likely to emerge as a significant known confounder in the diagnosis of psychiatric disorders, including PTSD, among the current generation of U.S. veterans.
