BALTIMORE - Sleep apnoea in healthy young adults may point to prior ecstasy abuse, according to a new study published in the journal Neurology.

Ecstasy (methylenedioxymethamphetamine – or MDMA), a popular recreational drug, acts as a selective neurotoxin to the neurotransmitter serotonin. In obstructive sleep apnoea, there is increasing evidence that brain serotonin dysfunction may play a role, writes principal investigator Dr Una McCann of the Johns Hopkins School of Medicine in Baltimore, USA.

The study set out to determine whether abstinent recreational MDMA users who had been drug free for at least 2 weeks have an increased prevalence of OSA. The team recruited 132 volunteers by advertising for “club drug users” in newspapers and fliers: 71 healthy recreational MDMA users and 62 controls were enrolled.

The control group consisted of 62 participants who had similar patterns of illegal drug use to the experimental subjects but had never taken MDMA. The MDMA users had to have taken the drug at least 25 times in the past, a number previously shown to have lasting effects on serotonin neurons. All of the volunteers were otherwise physically and mentally healthy and had abstained from drug use for at least 2 weeks prior to the study.

Using all-night polysomnography in a controlled inpatient research setting, the team assessed the rates of apnoeas and hypopnoeas, and compared the apnoea- hypopnoea indices of the two groups, controlling for body mass index, age, race, and gender.

Recreational MDMA users had significantly increased rates of obstructive sleep apnoea and hypopnoea compared with controls. Ecstasy users had more than eight times the risk of sleep apnoea compared with people who did not use the drug. The odds ratio for any form of sleep apnoea in MDMA users during non-REM sleep was greater than that associated with obesity.

The severity of OSA was significantly related to lifetime MDMA exposure.

These findings suggest that prior recreational ecstasy use increases the risk of obstructive sleep apnoea. They also support the notion that brain serotonin neuronal dysfunction plays a role in the pathophysiology of the sleep disturbance.

“The longer a person had used ecstasy, the higher the rate of sleep apnoea episodes”. “Brain serotonin neurons modulate sleep and breathing patterns,” explains Dr McCann. “Our findings not only indicate that ecstasy is a risk factor for developing sleep apnoea but also that there is a direct correlation with the extent and duration of prior exposure. However, the precise mechanisms involved are not clear yet.”

“Other factors associated with ecstasy use and sleep disturbances are cognitive deficits, increased impulsivity and altered neuroendocrine function,” the team of Johns Hopkins psychiatrists points out. However, it is not clear whether disturbed sleep is responsible for the behavioural changes seen in ecstasy users, or serotonin neurotoxicity may be the underlying common aetiology.