A study examined the effect of medical marijuana laws on older Americans (ie aged 51 or over) and found that there was a marked increase in wellbeing and hours worked.

The study was co-written by Johns Hopkins Bloomberg School of Public Health and Temple University. It appeared in the Spring 2019 issue of the Journal of Policy Analysis and Management.

The principal finding was that medical marijuana legalisation increases older adult labour supply.

What did the paper study?

The data for the study came from the 1992-2012 Health and Retirement Study (“HRS”). This survey tracks health and labour market outcomes among older Americans.

The study examined survey responses about symptoms that are connected with the ability to work. This includes frequency of pain, an overall health assessment, and symptoms of depression. The analysis used 100,921 participant responses that represented individuals with one or more of four health conditions that would qualify for medical marijuana treatment under most state laws (arthritis, cancer, glaucoma and pain).

The analysis matched implementation dates of 20 states’ medical marijuana laws to the HRS interview responses to track the possible effects of these policy changes.

Our study is important because of the limited availability of clinical trial data on the effects of medical marijuana. While several studies point to improved pain control with medical marijuana, research has largely ignored older adults even though they experience the highest rates of medical issues that could be treated with medical marijuana.
— Lauren Hersch Nicholas, PhD, assistant professor in the Bloomberg School's Department of Health Policy and Management

The findings

The study found that medical marijuana laws lead to increases in full-time work.

In the sample that would qualify for medical marijuana treatment, the researchers found a greater increase in full-time work after medical marijuana laws were passed.

In the full sample, researchers found a 5% increase in full-time work versus a 7.3% increase in the sample that qualified for medical marijuana. These results suggest that any decline in productivity resulting from medical marijuana usage, such as not being able to work at capacity while under treatment, is outweighed by increased capacity to work.

The study found that medical marijuana implementation leads to a statistically significant reduction in reporting pain and increase in the probability of reporting very good or excellent health for the qualifying sample.

These findings underscore the close relationship between health policy and labor supply within older adults. When we’re doing policy evaluations, we have to think not only about whether the policy is changing health outcomes, but also whether it does it in a way that supports labor force participation.
— Lauren Hersch Nicholas, PhD, assistant professor in the Bloomberg School's Department of Health Policy and Management