The goal of this clinical trial is to learn if an integrated protocol using multifocal non invasive brain stimulation and brain recording combined with cognitive training is effective in treating cognitive and affective symptomatology in patients with mild cognitive impairment and early stages of dementia. The main questions it aims to answer are: * Does multifocal non-invasive brain stimulation reduce cognitive and affective symptoms in patients with mild cognitive impairment and early stages of dementia? * Do some specific factors, such as education and cognitive reserve, affect the extent of the possible outcomes achievable from the intervention? * Do electrophysiological measures contribute identifying responders and non-responders to the treatment? Researchers will compare real non-invasive brain stimulation to a placebo stimulation (reproducing the same feeling of stimulation without actually stimulating the brain) combined with cognitive rehabilitation on general cognition measures and depression symptoms. Participants will * Undergo two treatment cycles (real stimulation or placebo over frontal and temporal ares of the left hemisphere) combined with cognitive training twice a week for two months. * Complete neuropsychological evaluations before the first rehabilitation cycle and at the end of each rehabilitation cycle. Caregivers will provide information on functional daily living activities for their relatives.