Lifestyle choices such as excessive alcohol consumption and tobacco use are well-known risk factors for stroke, but neurologists are learning more about strokes related to illicit drug use.

“It’s not just cocaine and methamphetamine; there’s a whole genre of synthetic products that we need to be aware about,” said Dr. Aparna Pendurthi, a PGY-4 neurology resident at Barrow. “There is medical literature just starting to emerge, but we’re only now kind of catching up to this epidemic.”

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), drug abuse has been implicated as the cause in 15 to 40 percent of strokes in people under age 35. It is the most common predisposing condition for strokes among this age group.

Marijuana is the most widely used illicit drug, with at least 200 million users worldwide. A SAMHSA study that looked at 2.8 million new illicit drug users in 2013 found that 70.3 percent of those users started with marijuana.

“More than half of new illicit drug users begin with marijuana because, it seems, it is readily available, fairly inexpensive, and publicly considered the safest recreational drug to use,” Dr. Pendurthi said.

To date, about five dozen case reports of suspected cannabis-related strokes have been published. Most of these cases were ischemic strokes, meaning they were caused by a blockage in a blood vessel that supplies blood to the brain.

According to Dr. Pendurthi, the absence of vascular risk factors in most patients, the temporal relation of symptom onset to cannabis exposure, and the recurrence of symptoms in those patients with re-exposure suggest a causal role of cannabis in these cases of ischemic stroke.

The American Stroke Association in 2015 called the possible link between marijuana and ischemic strokes “interesting but not yet definitive.”

“While the jury is still out in terms of the direct correlation between marijuana and stroke, in the last 10 years there has been an emergence of synthetic marijuana products, namely ‘spice’ or K2,” Dr. Pendurthi said. “This is a recreational street drug known for its many adverse effects, including a high incidence of seizures and myocardial infarction (heart attack).”

Spice is a mixture of herbs and spices that is typically sprayed with a synthetic compound similar to tetrahydrocannabinol (THC), which is the psychoactive component of marijuana. Physiological effects of spice include increased heart rate, increased blood pressure, and decreased blood flow and oxygen to the heart – which is known as cardiac ischemia.

There is medical literature just starting to emerge, but we’re only now kind of catching up to this epidemic.

-Aparna Pendurthi, MD, Neurology Resident

The first reported case of spice-associated ischemic stroke was in Florida in 2013. A 26-year-old man and his 19-year-old sister both experienced a stroke within a few hours of smoking spice. The spice was contaminated with butane, heavy metals, and fungal particulates.

Dr. Pendurthi said stroke is a fairly rare complication of heroin use but that cocaine and amphetamines have the strongest association with stroke of any illicit drug. The cocaine epidemic of the 1970s and 1980s established a causal relationship between cocaine and strokes.

The exact mechanism of cocaine-induced stroke remains unclear, but Dr. Pendurthi said there are likely a number of risk factors involved, including vasospasm, cerebral vasculitis, enhanced platelet aggregation, cardio embolism, and hypertensive surges associated with cerebral autoregulation.

Dr. Pendurthi said approximately three-fourths of people who have a cocaine-induced stroke have no vascular risk factors, but she noted that the issue is further complicated by the presence of contaminants in cocaine.

She said strokes associated with methamphetamine may be caused by transient elevations in blood pressure given that these strokes appear in regions of the brain where hypertensive hemorrhages – bleeding in the brain due to high blood pressure – are usually seen.

Learn about other risk factors for stroke.

Watch Dr. Pendurthi’s Neuroscience Grand Rounds Presentation.