The syndrome of mild cognitive impairment (MCI) is heterogeneous in terms of aetiology, psychopathology, and prognosis. It is characterised by cognitive deterioration significantly exceeding the decline attributable to aging but not reaching the severity of dementia. The prevalence of MCI is estimated to be 17% in the population over 65 years old. At neuropathological examination, a large proportion of patients with mild cognitive impairment, particularly of the amnestic type, show typical features of Alzheimer's disease. The former progresses to dementia at an annual rate of 10% to 15%. In some cases, however, there is stable impairment or remission. The neurodegenerative process of Alzheimer's disease can be demonstrated in at least some patients using volumetric magnetic resonance imaging, 18-FDG positron emission tomography, or biochemical markers in the cerebrospinal fluid. It is not yet known whether patients with mild cognitive impairment or at least those with predementia Alzheimer's disease can benefit from currently available symptomatic treatments. Patients with early-stage Alzheimer's are an important target group for treatment interventions aiming at slowing the neurodegenerative process.