People who use tobacco and cannabis have higher rates of depression and anxiety, researchers say.

A new study, carried out by a team of researchers from the University of California San Francisco, has found a significant association between tobacco and cannabis use and higher rates of depression and anxiety. Researchers examined data from 53,843 adults in the U.S. who participated in online surveys as part of the COVID-19 Citizens Health Study, conducted from 2020 to 2022.

Among the participants, 4.9% reported using only tobacco, 6.9% reported using only cannabis and 1.6% reported using both substances. The research team found 26.5% of participants in the co-use group experienced anxiety and 28.3% reported depression. The risk of anxiety and depression was lower in people who did not use either tobacco or cannabis – 10.6% and 11.2% respectively.

People who used both substances were approximately 1.8 times more likely to have mental health disorders compared to non-users. Additionally, co-use and cannabis-only use were associated with a higher risk of anxiety compared to tobacco-only use.

Tobacco and cannabis are among the most frequently used substances in the world. Researchers say the use of these substances has become more frequent because of the expanding legalization of cannabis in the nation.

Though the study does not determine the causation, researchers suggest the co-use of tobacco and cannabis is linked to poorer mental health outcomes. Integrating mental health support into tobacco and cannabis cessation programs may help in addressing the association.

"Engaging in both tobacco and cannabis is linked to diminished mental well-being," the researchers wrote.

Depression and anxiety in the U.S.

According to the Centers for Disease Control and Prevention (CDC), depression impacts approximately 16 million adults annually in the U.S. In general, approximately one in six adults will encounter depression at some point in their lifetime. It is not selective and can affect people of all ages or backgrounds.

It's common for people with depression to also experience other mental health conditions. Depression often coincides with anxiety disorders, like intense and uncontrollable feelings of anxiety, nervousness, fear, worry and panic. Anxiety disorders can be chronic and last for a long time, making it difficult for people to perform daily activities.

The CDC says smoking is more common in adults who experience mental health conditions like depression and anxiety, than the general population. In the U.S., roughly three out of every 10 cigarettes are consumed by people with mental health conditions.

Treatments for depression and anxiety

The treatment for depression and anxiety disorders can differ from one individual to another. It usually involves medication like antidepressants, talk therapy and cognitive behavioral therapy (CBT).