The concept of heterogeneity of Alzheimer's disease is based on molecular, neuropathological, clinical and neuropsychological features, and also supported by the observation that Alzheimer's patients differ in their response to pharmacological interventions. Recent investigations evaluating the therapeutic potential of cholinesterase inhibitors have disclosed the existence of at least two subsets of patients with dementia, defined as 'responders' and 'nonresponders' to this therapy. In this article, Paolo Liberini and colleagues suggest that the cluster of responders to the cholinesterase inhibitors might include a significant number of subjects with a rather selective dysfunction of the cholinergic system, as in the case of Lewy-body dementia. A neuropathological demonstration of this correlation should open up new therapeutic perspectives.