Even Knowing They Were Taking Placebos, Older Adults Showed Cognitive Gains in Small Trial

A new study from the Università Cattolica del Sacro Cuore in Milan suggests that placebo pills may provide genuine benefits for older adults—even when participants know they are taking a placebo. After three weeks of taking inactive tablets, healthy seniors demonstrated measurable improvements in memory, cognitive performance, and physical function.

The research, published in the International Journal of Clinical and Health Psychology, included 90 independently living older adults. Researchers compared three groups: one receiving no treatment, one taking a deceptive placebo presented as a beneficial supplement, and one taking an open-label placebo that participants were explicitly told contained no active ingredients.

How the Trial Was Designed

Participants were randomly assigned to one of the three groups and followed for three weeks. One group received no intervention, another took placebo pills described as beneficial supplements, and a third took identical pills while being informed that they were placebos that could still produce beneficial mind-body effects.

Before and after the intervention, participants completed questionnaires assessing perceived stress, well-being, sleepiness, fatigue, optimism, and beliefs about aging. They also underwent tests measuring short-term memory, selective attention, and physical performance, including walking speed and balance.

Unexpected Cognitive and Physical Improvements

Both placebo groups demonstrated better cognitive and physical performance than the no-treatment group.

Physical performance improved by approximately 7% in the deceptive placebo group and by 9.2% in the open-label placebo group, representing modest but potentially meaningful functional improvements.

Cognitive performance also increased across multiple assessments. Participants who believed they were taking a real supplement improved by 12.6% to 14.6%, while those knowingly taking a placebo improved by 6.9% to 21.5%, depending on the specific cognitive task.

The researchers noted that these improvements were comparable to those reported in some exercise and cognitive training interventions for older adults. The gains were particularly notable in short-term memory, a cognitive function that typically declines with age and is often difficult to improve without structured training programs.

Stress and Sleepiness Also Improved

Participants receiving the open-label placebo experienced the greatest reduction in perceived stress compared with both the deceptive placebo and no-treatment groups. They also reported feeling less sleepy during the day, suggesting improvements in alertness and perceived vitality.

The researchers suggest these psychological changes may partly explain the observed physical and cognitive improvements. Reduced stress and greater perceived energy are known to support concentration, motivation, and engagement in daily activities, which may indirectly enhance performance during testing.

Ethical Implications for Healthy Aging

The findings highlight the potential of open-label placebos as an ethical way to harness the placebo effect without deceiving patients. Even though participants knew the tablets contained no active medication, many still experienced measurable improvements in several indicators associated with healthy aging.

According to the researchers, the results support growing evidence that expectations, mindset, and self-perception can influence physical and cognitive functioning in later life. Engaging in a structured routine, combined with a clear explanation of mind-body mechanisms, may activate beneficial psychological and physiological responses.

Limitations and Future Research

The authors emphasize that the study was relatively small and lasted only three weeks. Larger studies with longer follow-up periods are needed to determine whether these benefits are sustained over time and whether similar effects can be observed in more diverse populations.

Nevertheless, the findings suggest that low-risk placebo-based interventions could eventually complement established strategies such as physical exercise, proper nutrition, and cognitive training to help older adults maintain independence and quality of life.

The study was conducted as part of the Age-IT project and supported by Italy's PNRR research funding program, reflecting growing interest in non-pharmacological approaches to promoting healthy aging. If future research confirms these findings, open-label placebo interventions could become a simple, low-cost addition to geriatric care aimed at supporting memory, mood, mobility, and overall well-being.