Archive restoration — 26 September 2026: This article has been restored from our original source files. Its publication date and reporting context remain unchanged; it is not a new update on current policy, availability or clinical guidance.
The most useful question about a treatment is not always whether it makes a symptom disappear. Sometimes it is whether a person can do more with the life they already have.
That is the idea at the heart of a large American study following older adults with chronic pain. The Study on Medical Marijuana and Its Long-Term Effects on Older Adults—better known as SMILE—is measuring pain, sleep and mood, but it is also tracking movement, cognition, side effects and quality of life over 12 months.
The study is not yet an answer. It is a protocol for finding better answers.
As of October 2025, researchers had enrolled 399 people aged 50 or over: 277 who intended to begin medical cannabis and 122 in a comparison group. Results are expected to begin appearing in 2027. Until then, SMILE should not be presented as proof that cannabis keeps older adults active, protects cognition or reduces other medicines.
What it already offers is a more mature model of research. It asks whether reported relief corresponds with observable changes in everyday life—and whether any benefit is accompanied by impairment, falls, interactions or other costs.
Why older adults need their own evidence
Older adults are often discussed as if evidence collected in younger people can simply be carried across. That is unsafe.
Ageing can change how medicines are absorbed, distributed and cleared. Many people also take several prescriptions for pain, sleep, blood pressure, heart disease, diabetes or mood. Adding a THC- or CBD-containing product may create overlapping effects or alter the way another drug is processed.
The outcomes also carry different weight. Drowsiness that is merely inconvenient for one person may increase the risk of a serious fall for another. A short period of reduced attention may affect driving, cooking, medication management or caring responsibilities. Conversely, a modest reduction in pain interference may be meaningful if it helps someone walk regularly, shop independently or return to a social activity.
This is why “does cannabis work?” is too blunt a question. Which product, at what dose, for whom, over what period and against which outcome all matter.
The existing literature has not answered those questions well. Studies frequently combine medical and non-medical use, include few older participants, rely on self-report or examine only short-term effects. Products vary in cannabinoid content, route and dose, making broad conclusions especially fragile.
What the SMILE study is doing differently
SMILE is a prospective cohort study, not a randomised clinical trial. Participants are not assigned cannabis or a placebo by researchers. One group consists of people seeking to start medical cannabis; the comparison group consists of people with chronic pain who do not intend to start it for at least six months.
The planned sample is 440 adults aged 50 and over, with roughly half expected to be older than 65. Eligible participants have chronic non-cancer musculoskeletal or neuropathic pain and are followed for one year.
Researchers collect quarterly questionnaires covering pain, physical and emotional function, side effects and quality of life. Participants complete cognitive assessments and pain-sensory testing, while blood and urine samples help document exposure. The study also uses smartphone check-ins and Fitbit data to capture pain, mood, sleep and physical activity closer to the moment they occur.
That combination matters.
A questionnaire completed months later can be influenced by memory, expectations and a person's general impression of treatment. Repeated check-ins reduce some of that distance. Activity and sleep data add a different kind of evidence: not a perfect measure of wellbeing, but an opportunity to test whether “I feel more able to move” appears alongside changed daily movement or sleep patterns.
The study also records the products people actually choose, including cannabinoid ratios, dose and route. That reflects real-world practice more closely than research that treats every cannabis-based product as interchangeable.
Measuring function without turning people into data points
There is a danger in both directions. Medical coverage can reduce older people to an image of frailty, while optimistic cannabis coverage can turn them into before-and-after testimonials.
Neither is adequate.
Healthy ageing does not mean living without illness, pain or assistance. It can mean preserving agency, connection and the ability to take part in valued activities. Those outcomes may include walking to a café, gardening, caring for a grandchild, sleeping well enough to meet friends or completing household tasks with less disruption.
SMILE's six core outcome areas include pain intensity and interference, physical function, emotional function, cognition, a participant's overall judgement of improvement, and adverse events. This gives benefit and harm space in the same frame.
That is a welcome improvement on reporting that celebrates lower pain scores without asking whether a person became more sedated, less steady or less cognitively sharp. It also improves on safety reporting that counts adverse events without asking whether treatment enabled a return to meaningful activity.
Good evidence needs both.
What earlier observational research suggests
A separate prospective study followed 299 medical-cannabis patients aged over 50 for six months. Their average age was 66.7, and around nine in ten were using cannabis for a pain-related condition. Most preferred oral products that were higher in CBD and lower in THC.
The cohort reported improvements in pain, sleep and quality of life. Forty-five per cent of participants with six-month data experienced a clinically meaningful improvement in pain interference, and the same proportion reached that threshold for sleep quality. Quality-of-life scores also improved, including in usual activities, pain or discomfort, and anxiety or depression.
Those findings deserve attention, but the design cannot prove that cannabis caused the changes. There was no untreated or placebo comparison group. People knew what they were taking, expectations may have influenced reports, and those remaining at six months may differ from those who did not complete follow-up.
There is another reason for caution. Several authors were affiliated with Tilray, the cannabis company whose products were used in the study, and the company supported the work. Declared industry involvement does not invalidate a study, but it should be visible when readers judge its design and conclusions.
SMILE's comparison group, longer follow-up and mixture of subjective and objective measures should provide a stronger real-world account. It will still remain observational, which means differences between people who choose cannabis and those who do not may affect the result even after statistical adjustment.
Cognition cannot be treated as a footnote
A 2026 crossover study offers a reminder that “function” must include thinking as well as movement.
Researchers tested 31 adults aged 65 to 78 after they smoked their preferred legal cannabis and again in a sober condition. The average product contained 18.7% THC. At 60 minutes, performance was poorer on two versions of the Trail Making Test, which assesses visual attention, processing speed and mental flexibility. Results on other tasks were mixed, and the study was small.
This does not tell us what happens with a prescribed low-THC oil, a carefully titrated dose, infrequent evening use or long-term treatment. It does show why product and timing matter. Evidence from a high-THC inhaled product should not be applied to every prescription, but neither should acute cognitive effects be ignored because a product is being used for a medical reason.
SMILE includes cognitive testing at baseline and 12 months. That can help distinguish the immediate feeling of intoxication from longer-term change, although it will not answer every question about short-lived impairment after individual doses.
For patients and prescribers, the practical point is simple: symptom relief and cognitive safety should be reviewed together.
Falls and medicine interactions need active monitoring
The US National Center for Complementary and Integrative Health notes that cannabis use is associated with injury risk in older adults and that cannabis may contribute to dizziness on standing, potentially increasing the danger of fainting and falls.
Those risks are not identical for every person or product. They become more relevant when THC is combined with medicines that also cause sedation, confusion or low blood pressure.
A 2026 conference abstract mapping possible interactions in older adults identified six broad medicine categories for attention: antihistamines; cardiovascular and antithrombotic drugs; central nervous system medicines; endocrine medicines; gastrointestinal medicines; and pain treatments. Its recommendations included a medication review, assessment of fall and cardiovascular risk, gradual titration and deprescribing where appropriate.
The abstract is not a completed clinical trial, and a potential metabolic interaction does not guarantee that a clinically important event will occur. It nevertheless reflects sensible prescribing practice. A new cannabis prescription should not be reviewed in isolation from everything else a person takes.
Patients should not stop an established medicine because an observational cannabis study reported lower co-medication use. Changes to opioids, sleeping tablets, antidepressants, anticoagulants or blood-pressure treatment need clinical supervision.
What this means for UK patients
SMILE is a US study of state-regulated products, so it does not directly evaluate the UK prescribing system.
In the UK, cannabis-based medicines remain specialist treatments rather than routine options for chronic pain. NHS guidance notes that only a small number of people are likely to receive an NHS prescription and warns that products containing THC can affect concentration, memory and driving.
For someone already holding a legal private prescription, the study's design offers a useful template for follow-up. Reviews should record more than a global “better” or “worse”. They should ask:
- Has pain become less disruptive, not merely less intense?
- Is sleep more restorative, and is there daytime drowsiness?
- Has walking, exercise or participation changed?
- Are memory, attention or balance different after dosing?
- Have there been falls, near misses or episodes of dizziness?
- Has any other medicine changed, and was that change supervised?
- Is the benefit large enough to justify side effects, impairment and cost?
Specific goals make these questions easier to answer. “Walk to the local shop twice a week” is more measurable than “feel healthier”. “Attend a weekly class without leaving early because of pain” says more about participation than a single number.
The goal is not constant surveillance. It is to ensure that a treatment meant to support life is judged by its effect on life.
What SMILE will—and will not—be able to tell us
The study's strengths are its size, one-year follow-up, comparison group, detailed product information and combination of surveys, sensors, cognitive tests and biological samples. Following new users from before treatment begins is especially valuable.
Its limits are equally important. Participants choose whether to seek cannabis, so the groups may differ in expectations, previous experiences, income, health behaviour or willingness to try new treatments. Wearable data can show movement and estimated sleep, but not why a person moved more or less. People may also change products and doses during follow-up, making the real-world picture more representative but harder to interpret.
The first published results will need to report retention clearly. If people who experience side effects or no benefit leave the study more often, outcomes among those remaining could look unduly positive.
Researchers should also avoid treating the entire over-50 population as one group. A healthy 52-year-old and a frail 82-year-old may differ substantially in metabolism, fall risk, cognition and the medicines they take. Product-specific and age-specific analyses will matter more than a single average effect.
The editorial view
The encouraging part of SMILE is not a result it has yet to produce. It is the seriousness of the question being asked.
Older adults deserve research that sees them as active participants in families, workplaces and communities—not as symbols of decline, and not as uncomplicated success stories for an industry. A worthwhile treatment should help preserve the things a person values while creating an acceptable burden of risk.
Medical-cannabis research has spent too long asking broad questions about broad product categories. SMILE moves closer to the decisions patients actually face: which formulation, in which person, changes pain, movement, sleep or mood; whether that change lasts; and what happens to cognition and safety alongside it.
The study may find benefit, harm, no meaningful difference or a mixture that varies by product and patient. Any of those outcomes would be useful if reported honestly.
Hope does not require pretending the evidence is finished. It can begin with measuring a fuller version of health.
Key takeaways
- SMILE is following adults aged 50 and over with chronic pain for 12 months, comparing people who begin medical cannabis with people who do not initially plan to use it.
- As of October 2025, 399 participants had enrolled: 277 in the medical-cannabis group and 122 in the comparison group.
- The study combines questionnaires, cognitive and sensory testing, blood and urine samples, smartphone check-ins and Fitbit activity and sleep data.
- An earlier 299-person observational cohort reported improvements in pain, sleep and quality of life, but it had no comparison group and industry involvement should be considered.
- A small 2026 study found reduced performance on some attention and executive-function tests shortly after older adults smoked a high-THC product.
- Falls, dizziness and interactions with other medicines should be reviewed alongside symptom relief.
- SMILE is observational, so it can strengthen real-world evidence but cannot remove every difference between people who choose cannabis and those who do not.
- Results are expected to begin appearing in 2027; the protocol itself is not evidence that medical cannabis improves healthy ageing.
Sources
- Real-Time and Long-Term Effects of Medical Marijuana on Older Adults: Protocol for a Prospective Cohort Study — JMIR Research Protocols
- Medical Cannabis for Patients Over Age 50: A Multi-site, Prospective Study of Patterns of Use and Health Outcomes — Cannabis
- The effects of naturalistic cannabis use on cognition and subjective experience in older adults with normal cognitive function — Journal of Psychopharmacology
- Cannabis and cannabinoids: safety considerations — US National Center for Complementary and Integrative Health
- A review of drug-drug interactions involving medical cannabis in older adults — Medical Cannabis and Cannabinoids conference abstracts
- Impacts of medical and non-medical cannabis on the health of older adults: a scoping review — PLOS One
- Medical cannabis — NHS
