Using amphetamines recreationally could accelerate aging of the heart.
Recreational amphetamine, commonly known as "ice," "speed," and ecstasy, is a central nervous system stimulant. Amphetamine sends the part of the nervous system that functions to accelerate heart rate, constrict blood vessels, raise blood pressure, and produce the "fight or flight" hormone adrenaline, into overdrive.
Given the effect of amphetamine on heart rate, blood vessels, and blood pressure, the abuse of stimulants is likely to have a stressful effect on the cardiovascular system over time. However, there have previously been few studies that explore these processes.
It is known that prolonged stimulant use causes premature aging of the skin. Following on from this knowledge, researchers from the University of Western Australia (UWA) aimed to find out whether amphetamine use prematurely ages the heart.
Albert Stuart Reece, associate professor of medicine at UWA, and collaborators measured levels of blood flow through the brachial artery in the upper arm, as well as the radial artery in the forearm, of 713 study participants.
Arteries harden as the body ages, and so the researchers aimed to assess the degree of artery stiffening in order to determine how the heart was aging in this population. The participants were in their 30s and 40s and attending a clinic for substance misuse.
The team used a standard blood pressure cuff on the upper arm of participants and a noninvasive monitoring system, called SphygmoCor, on the forearm to gather data.
SphygmoCor uses software that can calculate the biological vascular age of a person by matching the age, sex, and height of an individual with the extent of arterial stiffening.
The participants were divided into four groups depending on their drug use. There were 483 people who did not smoke, 107 people who did, 68 individuals who used the heroin substitute methadone, and 55 users of amphetamine.
Of the 66 times that the amphetamine group was monitored with the SphygmoCor, 94 percent of individuals had used the drug within the previous week, and almost half of the people in the group had used it the day before.
Amphetamine users had 'older' hearts than smokers, methadone users
Findings indicated that compared with the people who smoked and used methadone, the cardiovascular system of the amphetamine users appeared to be aging at a much quicker rate.
These results remained significant when other known cardiovascular risk factors - such as weight, cholesterol levels, and the inflammation indicator C-reactive protein - were taken into consideration.
As exposure to amphetamine is often repetitive and prolonged, the heart is exposed to the effects of the stimulant on a behavioral, chronic, and long-term basis. "It is, therefore, conceivable that stimulant abusers do physiological and cardiovascular harm," says the team. They note that it is not clear to what extent the damage might be reversible.
The authors say that the results confirm their concerns that amphetamine abuse increases heart age. However, as the study is observational, no firm conclusion can be drawn regarding cause and effect.
The aging process suggests a power function over time, as many physiological processes begin to fail over the course of a lifespan progressively. However, the new findings suggest that stimulant abuse may accelerate the degeneration of the physiological systems. The authors write:
"If, as has been demonstrated, the damage from stimulant abuse is actually a power function of time, then this, in turn, implies that the gathering global stimulant epidemic carries a further message of urgency which has largely not been appreciated."
The team point to other research for a possible explanation for their findings. The research showed that amphetamine use interferes with stem cell functioning and normal cell division. Hence, amphetamines may both impede tissue repair and increase tissue injury, the authors conclude.