Number of deaths and disabled individuals fluctuated amid legislation changes and the rise of new addictions.

A study published in February of this year in the journal Lancet Psychiatry sheds new light on the harm caused by illicit substance abuse in South America. The research analyzed data on mortality rates and years lived with disability attributable to the use of amphetamines, cannabis, cocaine, and opioids from 1990 to 2019, correlating them with legislation and public policies implemented in the region during that period.

The initiative relied on information from the Global Burden of Disease Study, a systematic study conducted by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, United States, in partnership with several scientific institutions worldwide.

"In the case of illicit drugs, South America is a very strategic region," says Dr. João Maurício Castaldelli-Maia, academic advisor of post-graduation at the Department of Psychiatry of the Faculdade de Medicina da Universidade de São Paulo (FMUSP) and first author of the article in Lancet Psychiatry. "We are the largest producer of cocaine in the world and a huge producer of cannabis, while in relation to opioids, we have low use when compared to the global average."

Among the trends observed in the last three decades, there has been a stabilization in the level of harm caused by marijuana in Uruguay, despite the legalization of cannabis in the country. In Brazil, there was a significant growth in the damage afflicted in the population due to the use of cocaine, followed by a stabilization and a decrease in the curve. Regarding opioids, the global average was much higher than the numbers in South America, although there was an increase in certain countries, such as Brazil and Ecuador.

The study used the DALYs (Disability-Adjusted Life Years) as its main metric, which is the sum of years lost due to premature death and years lived with some type of sequelae or disability, both taking into account the average life expectancy of the population.

"This is a topic that carries a lot of ideology, and we sought to take the utmost care to conduct a balanced discussion of the data," says Dr. João Castaldelli-Maia, who co-authored the article with 18 other authors from institutions in the United States, India, Chile, Colombia, and Argentina.

According to the researcher, before drawing any conclusions, a closer analysis of the data is needed. Mortality and sequelae rates, for example, vary significantly among different types of drugs. While the DALYs rate associated with cannabis per 100,000 individuals is below 20, in cocaine, this ceiling rises to 60, and in the case of opioids, to 180 cases. Regarding amphetamines, the number of years lived with disability due to the use of the drug is more than double the years lost due to premature death in the global average in 2019.

There are several specific factors that contribute to explaining these rates. The age range of amphetamine users is quite young, and there is widespread recreational use of this drug. On the other hand, those who suffer from chronic pain and pre-existing conditions are more susceptible to opioid dependence, which is often prescribed to treat these conditions. In addition, the pattern of substance use, poverty, income inequality, and the fact that South America is a major supplier of cocaine makes this place unique for research on the subject.

Continent under observation

"After a decade of implementing the marijuana regulation law, which controls the sale of the substance by the state, Uruguay has shown a high prevalence of users and drug-related disorders, but within a stable trend. "Among the different models of legalization in the world, Uruguay's model is of interest," says Dr. João Castaldelli-Maia. "What is happening in the US and Canada, for example, is completely different, as cannabis is treated much more as a product and an increase in the number of dependents can already be observed (according to Imtiaz and colleagues' article published last month)."

Meanwhile, Brazil is negatively emerging in relation to the use of opioids, being the country with the highest increase in the DALYs index of the study. "Despite a low burden of disorders compared to other regions of the world, we see a dangerous growth and it begins to be something that draws attention," says Dr. Castaldelli-Maia. As the use of injectable opioids (such as heroin) is quite uncommon in the country, there is a need for greater clarification of the shared harms with diseases that generate chronic pain and demand drug use in the territory.

For the researcher, the mental health field still lacks comprehensive investments, including the treatment and prevention of dependencies. In this context, cocaine becomes one of the most relevant substances for investigation in South America, given the high rates of drug-related disorders in almost all countries in the region and the promising results obtained by harm reduction programs.

During the analyzed period, Brazil showed a significant increase in DALY indexes but began to register a decline from 2017, while Argentina and Uruguay were experiencing slight growth until 2010 and also managed to reverse this trend. "These are countries that have implemented very important programs, investing heavily," says Dr. Castaldelli-Maia. "The numbers reflect this, cocaine is the substance that has received the most investment among illicit drugs in terms of preventive programs."

This prevention includes highly complex scenarios, ranging from educating the population about the harms of the substance, to combating drug trafficking and producer zones, to legal and judicial issues surrounding sales. "It is not only about investing in health but also in security and offering treatment and social support," says the researcher. "They are costly projects, but managed to yield some results."

Check out the full article in Lancet Psychiatry: https://www.sciencedirect.com/science/article/pii/S0376871623000030