The benefits of medical marijuana are debated by doctors and researchers across the country. On the one hand, marijuana may help ease the symptoms of several diseases — from glaucoma to cancer; and on the other, its effects on the brain are not so good — it can cause anxiety and memory problems.

A team of New York neurologists recently published a study that adds to the positive side of the ledger: they found that marijuana may actually relieve the symptoms of certain brain diseases.

Specifically, patients suffering from multiple sclerosis appear to benefit when given medical marijuana.

A majority of patients who consumed marijuana experienced relief from MS symptoms, such as spasticity and pain related to spasms.

Multiple sclerosis, or MS, is an autoimmune disease that affects the brain and spinal cord. During the disease, inflammation damages the protective covering around nerve cells, myelin, causing problems with gait and motor control. MS has been linked to various environmental factors, but its exact cause is unknown.

The study reviewed 34 different clinical trials and sampled over 2,000 MS patients who were prescribed marijuana as either a pill or oral spray. Many of the patients were given Sativex®, a cannabis spray approved for the treatment of MS spasticity in Europe and around the world, but not available in the United States.

The scientists discovered that a majority of patients who consumed marijuana experienced relief from MS symptoms, such as spasticity and pain related to spasms. The finding is good news for MS patients. The disease has several drug treatments that help slow down and control symptoms, but no precise cure.

Marijuana did not produce any significant brain-related side effects, such as impaired memory, in the study participants.

Though some in the study suffered from dizziness, nausea, and fatigue, these side effects were expected and rarely led to anyone dropping out of the study. Fewer than 1% of all participants experienced severe side effects such as hallucinations or seizures.

Depression was also a concern. “If you have a brain disease like MS for example, you may already have some depression or cognitive impairment, so we were careful to see if cannabis made this worse,” Barbara Koppel, a neurologist at New York Medical College and senior author of the study said in a statement.

The team found no link between using marijuana and rates of depression and suicidal thoughts, more good news for marijuana's potential as a form of relief from certain brain diseases.

This study is published in the journal, Neurology.