As more tales of vape users getting sick come to light (popcorn lung, people), scientists are focused on e-cigarettes’ affects on the lungs and the heart. But what about how vaping affects the mind? Can e-cigarettes change your brain?

There isn’t a lot of research on this, but a new paper hints that vaping and depression have a strong, yet mysterious, connection.

The study reveals that vape users are twice as likely to be diagnosed with depression compared to people who have never vaped at all. The same holds true for former users: People who vaped in the past were 1.6 times more likely to have been diagnosed with depression than those who never pick up an e-cigarette.

“E-cigarettes are not as harmless as many people may think, and it is important that they know that there might be potential mental health effects associated with their use,” Olufunmilayo Obisesan, a post-doctoral fellow at Johns Hopkins University and author on the study, tells Inverse.

The paper was published this week in the journal JAMA Network Open.

Does vaping cause depression?

The results are based off of data from the 2016-2017 Behavioral Risk Factor Surveillance System, an annual survey conducted in the United States by the Centers for Disease Control and Prevention. The researchers analyzed responses from 892, 384 participants, and looked for connections between depression diagnoses and vaping habits.

Daily users were 2.3 times more likely to have had a depression diagnosis than those who didn’t vape at all. They were also more likely to report poor mental health overall than those who didn’t vape. The same was true for those who vape less frequently.

People who vaped daily had the highest odds of reporting a depression diagnosis (here, an odds ratio of one means that there's no association between vaping and depression). JAMA Network Open

The results confirm past preliminary evidence. A survey presented in March of this year, for example, suggested that vape users are more likely to report a depression diagnosis than non-users.

But there is one question left unanswered: Why are vape users more likely to have depression than non-users?

Scientists don’t know whether people who already struggle with mental health issues are drawn to vaping, or if there’s something about vaping that heightens risk of depression.

The researchers argue that vaping could be both a cause or a consequence of depression.

Lessons from cigarette research

Research on cigarette smokers could offer some clues, as there is a similar connection between tobacco use and depression. A 2017 review found evidence for both ideas.

Some studies support a “self-medication model,” which suggests that people start smoking cigarettes to cope with depression or anxiety. Others support an alternative theory — that consistent or prolonged smoking makes people more susceptible to anxiety or depression.

Vaping is not the same as smoking — vaporizers don’t actually burn anything, and as a result don’t release the dozens of cancer-causing toxins that cigarettes do. But they do deliver nicotine — sometimes far more than a traditional cigarette.

Previous research suggests that nicotine disrupts dopamine production in the brain, increasing sensitivity to stress and dampening the ability to cope with depression. Other than nicotine, some vape liquids contain heavy metals, which may also play a role, Obisesan says.

“Trace metals such as lead and aluminum are also present in many e-cigarettes and have established negative effects on the central and peripheral nervous system, which could contribute to the observed association between e-cigarette use and depression,” she says.

These data don’t reveal whether or not that is the case. But the results do indicate that vaping may have a complex relationship with depression reminiscent of the one that’s seen in smokers. More work is needed before we can determine vaping’s affects on our brain, alongside the popular practice’s affects on the rest of our body.

Abstract:

Results: Of the 892 394 participants (414326[29.0%] aged ≥ 60 years; 502448 [51.3%] women), there were 28 736 (4.4%) current e-cigarette users, of whom 13 071 (62.1%) were aged between 18 and 39 years. Compared with never e-cigarette users, current e-cigarette users were more likely to be single, male, younger than 40 years, and current combustible cigarette smokers (single, 120 797 [24.3%] vs 10 517 [48.4%]; men, 318 970 [46.6%] vs 14 962 [60.1%]; aged 18-39 years, 129 085 [32.2%] vs 13 071 [62.1%]; current combustible cigarette use, 217 895 [7.9%] vs 8823 [51.8%]). In multivariable adjusted models, former e-cigarette users had 1.60-fold (95% CI, 1.54-1.67) higher odds of reporting a history of clinical diagnosis of depression than never users, whereas current e-cigarette users had 2.10 (95% CI, 1.98-2.23) times higher odds. Additionally, higher odds of reporting depression were observed with increased frequency of use among current e-cigarette users compared with never users (daily use: odds ratio, 2.39; 95% CI, 2.19-2.61; occasional use: odds ratio, 1.96; 95% CI, 1.82-2.10). Similar results were seen in subgroup analyses by sex, race/ethnicity, smoking status, and student status.

Conclusions and Relevance:This study found a significant cross-sectional association between e-cigarette use and depression, which highlights the need for prospective studies analyzing the longitudinal risk of depression with e-cigarette use. If confirmed by other study designs, the potential mental health consequences may have regulatory implications for novel tobacco products.