Low-dose ionizing radiation may be a promising, although possibly controversial, therapy for Alzheimer’s disease, according to the researchers behind a small new pilot study.

Their inspiration was a 2015 case in which a woman with the disease received multiple computerized tomography, or CT, scans. She reportedly showed so much improvement in cognition, speech, movement and appetite afterward that she was discharged from hospice to a nursing home. 

To determine whether this was a repeatable finding, investigators engaged four participants with severe but stable Alzheimer’s to receive three radiation treatments spaced two weeks apart. They then compared pre-treatment and post-treatment measures of cognition and behavior.

Caregiver/family member descriptions, photos and videos suggested “remarkable improvements” beginning within one day of treatment, according to Morris Freedman, M.D., of Baycrest Health Sciences, Toronto, and colleagues. In one case, the patient’s daughter requested ongoing treatment. There were only minor improvements on quantitative measures in three of the four patients, however, and one patient showed no changes at all, they reported.

Low-dose ionizing radiation therapy for Alzheimer’s is based on the hypotheses that oxidative stress is a major factor in the development of the disease, and that stimulation of protective systems in the brain by CT scan will reverse or delay progression. 

The investigators propose that ongoing low-dose ionizing radiation therapy could produce “greater and long-lasting recovery” from Alzheimer’s disease symptoms than found in the study. “[D]ouble-blind placebo-controlled trials are required to determine the efficacy of this therapy and its limitations,” they said. “Trials in participants with less advanced Alzheimer’s disease should also be considered.”

Full findings were published in the Journal of Alzheimer’s Disease.