According to the Centers for Disease Control's National Survey on Drug Use and Health, seniors are the fastest-growing users of medical marijuana in the country.

According to the September study, among those who had tried marijuana in the last month, the 55-and-older crowd was the quickest-growing demographic in the years 2002 to 2014: The number between the ages of 55 and 64 who used marijuana grew 455 percent, and the number 65 and older grew 333 percent.

Dana Rohrabacher, a Republican congressman from California, used cannabis lotion for his arthritis, time-stamping seniors' new affinity for medicinal marijuana products.

Rohrabacher tried a topical, wax-based marijuana treatment. That night was "the first time in a year and a half that I had a decent night's sleep because the arthritis pain was gone," Rohrabacher said last year.

Pennsylvania is about to issue new regulations on dispensing legal medicinal marijuana, and senior support is at an all-time high.

"More than half the country has legalized medical marijuana. Now, older people who used marijuana when they were younger, perhaps in college, then entered the professional world and had families and stopped using - now that it's legal in their state, what we're finding [is] they're going back to it, trying it again for health and wellness," said Chris Walsh, editorial director and founding editor of Marijuana Business Daily in Colorado.

"Medical marijuana is now mainstream. You can walk into a heavily regulated storefront dispensary, and that prompts more people to consider it a viable medical option," Walsh added.

In particular, many new lotions, creams, and pills an older person might use are heavy on a compound called CBD - cannabidiol, the painkiller - as opposed to THC, the chemical that gets you high.

Older people prefer traditional forms of medication, fueling growth in the industry, said Nick Kovacevich, co-founder and CEO of Kush Bottles, a medical marijuana packaging company.

"The ways you can ingest are changing. For instance, a 60-year-old might not be into smoking," Kovacevich said. "Now, in many states, you can get pills, topicals or tinctures that you put under the tongue. Even in the last four years, the forms you can take have evolved into edibles like gummies, hot chocolate, lollipops, and lozenges."

Heavier users, such as cancer patients, often prefer waxes or oils, skin patches, sublingual strips, creams, sprays, and lotions.

"That's the wave of the future. The elderly like creams and sprays and rubs, because they're used to ointments and gels for pain management and control," Kovacevich said.

Conditions among the elderly that are listed as uses for medical marijuana include glaucoma, post-traumatic stress disorder, spasms, epilepsy, chronic pain, backaches, multiple sclerosis, and Parkinson's.

Seniors campaigning for wider uses include Robert Platshorn, 73, who was born in South Philadelphia, grew up in Cherry Hill, and now lives in Florida.

"There are millions of junkie seniors taking OxyContin, fentanyl, and Darvocet," said Platshorn, who founded, an nonprofit and activist group of seniors lobbying for passage of medical marijuana in Florida.

"It's a natural for physicians to prescribe medical marijuana for seniors who are in pain but who don't want to feel loopy. And opioid addiction can be avoided," he added.

New studies point to medical marijuana as a possible treatment for Alzheimer's.

Gary L. Wenk, a professor of psychology, neuroscience, and molecular virology, immunology, and medical genetics at the Ohio State University and Medical Center, studies chronic brain inflammation in Alzheimer's disease. His research into cannabinoids led him to conclude that while they are no cure, they may slow the onset of Alzheimer's.

"Low doses of marijuana for prolonged periods of time at some point in your life, possibly when you're middle-aged to late middle-aged, is probably going to slow the onset or development of dementia, to the point where you'll most likely die of old age before you get Alzheimer's," Wenk said in a 2014 interview with Leaf Science, a Canadian marijuana-news website.

Even Philadelphia's medical schools are getting in on the research of medical marijuana. In May, the Institute of Emerging Health Professions at Thomas Jefferson University announced the creation of the Center for Medical Cannabis Education & Research, which provides information and guidance to clinicians and patients about the medical uses of marijuana and cannabinoid-focused therapies.

With legalization, Platshorn argued, seniors "need to be part of the conversation surrounding legalizing medical marijuana, and its benefits."