While previous research has suggested that older adults may have a diminished capacity for experiencing pain relief, University of Florida researchers have found that with the correct dosage, electrical stimulation treatment can help ease back pain in older adults.
Neurobiological changes that happen with aging make it more difficult for older people to inhibit pain and experience relief. Electrical stimulation therapy could offer older adults with chronic pain an effective alternative to other treatments, including prescription painkillers, the UF researchers say.
The study is the first to compare response to transcutaneous electrical nerve stimulation therapy, or TENS, across age groups. Results appear online ahead of print in The Journal of Pain.
The key to TENS' effectiveness in older adults is ensuring they receive an adequate dose, or amplitude, of electrical stimulation, said lead investigator Corey Simon, Ph.D., D.P.T., a postdoctoral researcher in the Pain Research and Intervention Center of Excellence at the UF Clinical and Translational Science Institute.
"We found that TENS was adequate for relieving pain across the lifespan, independent of age. Everybody got better, both in clinical pain measures and experimental pain measures," said Simon, who conducted the study with support from a UF CTSI training award as part of his dissertation research for a doctoral degree in rehabilitation science at the UF College of Public Health and Health Professions. "A key finding was there was an age difference in TENS dosage. Older adults needed a higher dosage to experience similar relief."
In clinical settings, TENS dosage is often standardized based on its use in young and middle-aged adults. For the UF study, dosage was individualized, with participants receiving amplitude that they found to be strong, but tolerable, and not painful.
The UF study included 60 adults with chronic low back pain, including 20 young adults ages 18 to 39, 20 middle-aged adults ages 40 to 56 and 20 older adults ages 57 to 79, who received four sessions of TENS treatment over a three- to four-week period. TENS therapy uses a small battery-operated machine that delivers low-voltage electrical current through electrodes placed on the skin. It is commonly used to treat acute pain, including pain with childbirth, or chronic pain, such as osteoarthritis. Scientists believe TENS works by activating the opioid receptors in the brain and spinal cord.
Across all age groups, participants in the UF study experienced a 48 percent improvement in resting pain. While wearing the TENS device, participants' pain with movement was reduced by 34 percent and their physical function rating increased by 14 percent.
"This study is good news for people with pain because they need lots of treatment options and TENS is a low-risk option," said senior author Steven George, Ph.D., P.T., a UF associate professor of physical therapy and director of the Doctor of Physical Therapy program and the Brooks Rehabilitation research collaboration at the College of Public Health and Health Professions.
Earlier studies of TENS' effectiveness in treating chronic low back pain showed mixed results, but those studies used lower doses and fewer treatment sessions, George said. Recent research has demonstrated that TENS can be effective with regular use, at higher amplitudes and for certain types of pain.
"TENS seems to be effective with reducing movement-evoked pain," George said. "TENS is not a panacea. It's not as if you put it on and then you never have pain again. It may be more helpful to apply it when you are doing some movements."
Future work needs to compare the effectiveness of TENS to drug treatments for controlling chronic low back pain in older adults, Simon said.
"TENS is inexpensive, it is a conservative intervention and it is potentially safer for older adults where pharmacologic agents may pose a higher risk," he said. "Comparing the efficacy of TENS to pharmacologic agents is an important next step for geriatric pain research."