Transcranial direct current stimulation and cognitive training in the rehabilitation of Alzheimer disease: A case study

In the present study we tested the cognitive effects of transcranial direct current stimulation (tDCS) in a case of probable Alzheimer disease (AD). The patient (male, 60 years, mild AD) underwent two cycles of treatments, separated by 2 months. In the first cycle, active stimulation (10 sessions, 2 mA for 20 min; anode over the left dorsolateral prefrontal cortex) was followed by computerised tasks (CTs) specifically chosen to engage the most impaired cognitive processes in the patient (tDCS+CT condition). In the second cycle, which was structured as the first, CTs were administered after placebo stimulation (sham+CT condition). Effects on cognitive performance were evaluated not only by the CTs, but also by neuropsychological tests assessing global cognitive functioning. Statistical analyses revealed that whereas the tDCS+CT condition had few effects on the CTs, it induced a stability of the patient's global cognitive functioning lasting approximately 3 months, which was not achieved when the patient underwent sham+CT condition. Therefore, the synergetic use of tDCS and CTs appeared to slow down the cognitive decline of our patient. This preliminary result, although in need of further confirmation, suggests the potentiality of tDCS as an adjuvant tool for cognitive rehabilitation in AD.