(CNN) – Dr.  Sue Sisley  noticed an unexpected trend among her patients. The psychiatrist works with  veterans who struggle with post-traumatic stress disorder . Many do not feel well with all the medications they take to manage anxiety, insomnia, depression and flashbacks .

“There are a few drugs on the market that work, and even those may be inadequate,” Sisley said. “They end up taking eight, ten or twelve different medications, and after so many, they’re suddenly  like zombies .”

However, some of these patients were beginning to feel better. They seemed much more present. She wanted to know what was changing. They told him they found an alternative to all those medications.

They were self-medicating with marijuana.

“I was dumbfounded and more and more patients came out of the shadows to reveal that they were having some useful experiences with marijuana,” Sisley said.

She recognized the advances, but, like any good scientist, she did not want to rely on anecdotal evidence. I wanted a documented test, clinical trials of large patient populations that proved that marijuana was the right approach to the treatment of post-traumatic stress disorder. People use it to treat a variety of medical problems, such as multiple sclerosis, arthritis, epilepsy, glaucoma, HIV, chronic pain, Alzheimer’s disease, cancer and others.

With the legalization of medical marijuana in almost half of the US states, more doctors wonder what impact this drug really has on patients. They want to know about its long-term effect.

Sisley sought answers to these questions, but when she decided to do the studies and apply for federal approval, she encountered bureaucracy and resistance, as did many other researchers before her.

That’s because marijuana is one of the most closely controlled substances under US federal law. The government of the United States considers that it is a  Class I drug, that is, the DEA considers that it has no medicinal value. It is at the same level of heroin and LSD. To research marijuana, scientists need the approval of several federal departments. And approval is rare.

Most marijuana studies focus on the harm caused by the drug. Studies on its medicinal properties are minor, are in preliminary stages or observation in the best case.

A bipartisan bill – by Republican Rand Paul and Democrats Cory Booker and Kirsten Gillibrand – that was  introduced in the Senate in March would ease some of the restrictions on the study of the drug. But the project is on the commission for the time being. If it happens and scientists can begin to study the drug seriously, there are several areas that can be targeted, in addition to post-traumatic stress disorder.

Here are 10 of them, depending on the ailments for which people commonly use medical marijuana.


In a  human study of 10  HIV-positive marijuana smokers, the scientists found that people who smoked marijuana ate better, slept better, and had a better mood. Another small study of 50 people found that patients who smoked cannabis had less  neuropathic pain.


Medical marijuana and some of the plant’s chemicals have been used to help Alzheimer’s disease patients gain weight, and research found that it decreases some of the hectic behavior that  patients may exhibit.  In  a cell study , the researchers found that it  slowed down the progress  of protein deposits in the brain. Scientists believe that these deposits may be part of what causes Alzheimer’s disease, although it is not yet known what causes the disease.


A  study of 58 patients  using marijuana derivatives found that they had less pain caused by arthritis and that they slept better. Another review of studies  concluded that marijuana can help fight pain caused by inflammation.


The studies are contradictory. Some cell work showed that smoking marijuana could dilate the airways, but some patients experienced a feeling of tightness in the chest and throat. A study in mice  found similar results.


Studies in animals  showed that some extracts of marijuana can kill certain cancer cells. Other cell studies  show that it could stop the growth of cancer,  and with mice,  THC, the psychoactive ingredient in marijuana, improved the effects of radiation on cancer cells. Marijuana can also prevent the nausea that often accompanies chemotherapy treatment.

Chronic pain

Some studies in animals and humans show that cannabinoids can have a  “substantial analgesic effect” . They were widely used for pain relief in the 19th century. Some cannabis-based medicines, such as Sativex, are being tested in patients with multiple sclerosis and are used to treat cancer pain. The medication was approved in Canada and in some European countries. In another study, which included  56 patients , scientists observed a 30% reduction in pain among those who smoked marijuana.

Crohn’s disease

In  a small pilot study  of 13 patients seen over three months, researchers found that inhaling cannabis improved the lives of people suffering from  ulcerative colitis  and  Crohn’s disease . It helps relieve pain, limited the frequency of diarrhea and helped with weight gain.


The use of medical marijuana extract in the first tests at the  NYU Langone Medical Center showed a 50% reduction in the frequency of certain seizures in children and adults in a study of 213 patients recently.


Glaucoma is one of the main causes of blindness. Scientists have investigated  the impact of THC on this disease in the optic nerve and have found that it can lower eye pressure, but it is possible that blood pressure is also reduced, which could damage the optic nerve due to a reduced supply of blood.

Multiple sclerosis

The use of marijuana or some of the plant’s chemical products could help  prevent muscle spasms , pain, tremors  and stiffness , according to the first stages  of observation studies , mostly with animals. The disadvantage: it can affect the memory, according to  a small study with 20 patients.