Effects of “Isolated” Transcutaneous Electrical Nerve Stimulation on Memory and Affective Behavior in Patients with Probable Alzheimer’s Disease

Background: In previous studies, transcutaneous electrical nerve stimulation (TENS), tactile stimulation, and a combination of the two resulted in cognitive and affective improvements in patients with Alzheimer’s disease (AD). As in those studies the therapist was present during the treatment of the experimental and control group (sham stimulation), a positive effect of the combination of TENS with interpersonal communication could not be excluded. Therefore, the effects of “isolated” TENS, i.e., in the absence of the therapist, on memory and affective disturbances in AD patients were examined. Methods: Eighteen subjects (78–92 years old) met the NINCDS-ADRDA criteria for the clinical diagnosis of probable AD. To evaluate treatment effects, the experimental group (9) and the control group (9) underwent a number of neuropsychological tests and two observation scales. Results: Treatment effects were observed for nonverbal short-term (Visual Memory) and long-term (Face Recognition) memory, word fluency (Verbal Fluency), and need of help, whereas patients’ affective behavior did not improve. Conclusions: The results of the present study show that isolated TENS has a positive effect on patients’ cognitive and independent functioning; however, isolated TENS appeared not to have a therapeutic effect on patients’ affective behavior.