Treatment of late-life depression: a role of non-invasive brain stimulation techniques

Late-life depression (LLD) is a frequent complication of the ageing process, occurring in up to 5% of community-dwelling elderly and in a higher proportion of subjects with coexistent medical illnesses. Its presence has been consistently associated with cognitive impairment, greater disability and increased mortality. Approximately half of patients with LLD have evidence of subcortical ischaemic damage in prefrontal circuits revealed by MRI. This might constitute the biological substrate of the cardinal symptoms of depression and of executive dysfunction. An important proportion of patients with LLD do not achieve remission of their depressive symptoms in spite of adequate pharmacological and psychotherapeutic treatment. In addition, a group of LLD patients progress to further impairment and disability in the form of a dementing disorder. There is an imperative need to develop new treatment strategies for LLD. Non-invasive brain stimulation techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are safe and efficacious interventions that might be used in combination with other therapeutic options to improve treatment outcomes. However, there are still questions regarding the optimal way in which rTMS and dTCS should be delivered as well as to the way in which we may identify the subjects who will benefit the most from these interventions.