The study comes from skin experts including Sewon Kang, MD, of the University of Michigan's dermatology department.
Kang's team put the lotions in separate, identical bottles so no one could tell which bottle contained the retinol lotion.
The researchers' lotions were tested by 36 healthy people who were at least 80 years old at two senior centers in Michigan.
After that, half of the elders got the retinol lotion; the others got the placebo lotion. They were scheduled to use their assigned lotion on their inner upper arm three times weekly for six months.
At the end of the six-month study, participants got another skin biopsy and more photographs of their inner upper arm.
The elders who had used the retinol lotion had a reduction in the appearance of fine wrinkles in their inner upper arm. Those changes started after four weeks of retinol treatment and lasted throughout the study.
Wrinkles didn't change for those in the placebo group.
The before-and-after skin biopsies show that retinol treatment boosted structural components in the elders' skin.
Retinol can irritate the skin. By the end of the study, most patients in the retinol group had some skin dryness or irritation. As instructed, they cut back on their retinol use in light of those side effects.
Retinol didn't erase wrinkles forever. The researchers followed 11 participants for six months after retinol treatment ended. The skin differences seen in the study faded during that time.
The study appears in the Archives of Dermatology.
The journal notes that Kang and three other researchers are named as inventors on a patent application for methods to treat aging skin.