Effects of high-frequency cranial electrostimulation on the rest-activity rhythm and salivary cortisol in Alzheimer's disease - A pilot study

Objective. In previous studies, cranial electrostimulation (CES) had positive effects on sleep in depressed patients and in patients with vascular dementia. The present study examined the effects of low-frequency CES on the rest-activity rhythm and cortisol levels of patients with probable Alzheimer’s disease (AD). Method. It was hypothesised that a decreased level of cortisol would parallel a positive effect of low-frequency CES on nocturnal restlessness. Sixteen AD patients were randomly assigned to an experimental group (n = 8) or a control group (n = 8). The experimental group was treated with CES, whereas the control group received sham stimulation, for 30 minutes a day, during 6 weeks. The rest-activity rhythm was assessed by actigraphy. Cortisol was measured repeatedly in the saliva throughout the day by means of salivette tubes. Results. Low-frequency CES did not improve the rest-activity rhythm in AD patients. Moreover, both groups showed an increase instead of a decrease in the level of cortisol. Conclusions: These preliminary results suggest that low-frequency CES has no positive effect on the rest-activity rhythm in AD patients. An alternative research design with high-frequency CES in AD is discussed.