A recent study from the Washington State Institute for Public Policy found that people across the state who lived near licensed marijuana stores were more likely to be diagnosed with cannabis use disorder.

The report, released in September, assessed how often Medicaid recipients between the ages of 12 and 64 have been diagnosed with cannabis use disorder and other health issues since recreational marijuana was legalized by Washington voters in 2012.

It describes cannabis use disorder as “characterized by continued use of cannabis despite distress or impairment in one’s life.” The study notes it is also ”robustly tied to depression, anxiety, and other mental health disorders.”

Researchers compared individuals who lived within a 10-minute drive of stores selling marijuana to those who lived further away. They used Medicaid claims data to determine how often people were diagnosed with cannabis use disorder. Data from 2012 to 2023 helped researchers establish diagnosis, hospitalization and treatment rates before and after licensed retailers opened.

Over that time, the number of cannabis shops soared across the state. In 2014 there were fewer than 50 active retailers operating across Washington, according to the report. In 2023 there were more than 450.

The study found that individuals between the ages of 12 and 20 — under the legal age to purchase marijuana — were 13% more likely to be diagnosed with cannabis use disorder if they lived near a cannabis shop. Adults 21 years old and up were 7% more likely to be diagnosed.

According to the Centers for Disease Control and Prevention, symptoms of cannabis use disorder include cravings, using marijuana despite it causing personal or professional issues, and being unable to stop using it. People who start using cannabis when they’re young or those who use it regularly are more at risk of developing the disorder.

Amani Rashid, a senior research associate with the policy institute, said living near multiple marijuana shops increased the chance of receiving this diagnosis or being hospitalized for a related issue. She said there could be a few potential explanations for these findings.

“With more retailers, you have potentially a more competitive market, and with more competitive markets, you potentially have lower prices,” Rashid said. “You might have more advertising in those neighborhoods. It’s possible retailers will try to differentiate their products more via packaging or different THC concentrations and so on.”

The study also assessed the rate Medicaid enrollees with cannabis use disorder were diagnosed with mental health issues associated with marijuana use. Researchers found that those living near cannabis shops were more likely to receive an anxiety, depression, bipolar or psychotic disorder diagnosis for the first time after being diagnosed with cannabis use disorder.

Democratic Washington State Rep. Lauren Davis wasn’t surprised by these findings. She represents state District 32, which includes Shoreline and Lynnwood. Davis has advocated for stricter regulations on recreational marijuana for years, and believes legalizing it created a number of unintended consequences.

“As a result, we have all sorts of products that are of an incredibly high potency,” she said. “We also have pervasive cannabis retail outlets, we also have pervasive advertising and taken together, in aggregate, those have had significant impacts.”

Davis’ proposals — which have included limiting access to products with high THC concentrations and potency caps — haven’t received widespread support. Still, she believes her colleagues at the state capital shouldn’t ignore the risks to public health posed by cannabis.

KNKX reached out to the marijuana business trade group Washington Cannabusiness Association about the policy institute study. In an email, the group’s spokesperson, Aaron Pickus, declined to comment on the report’s findings, but said that “it does not appear that the report distinguished between cannabis obtained from legal stores or from the thriving illicit marketplace, which has no guardrails on safety or youth access.”

Pickus also claimed licensed cannabis retailers are much more effective at preventing underage customers from purchasing marijuana than alcohol and tobacco retailers.

The report did not provide any policy recommendations for state officials. Rather, it is part of an ongoing cost-benefit analysis, required by state law, to assess the effects of legalizing recreational marijuana on areas such as public health, the economy and criminal justice.