Cognitive rehabilitation for severely demented patients is a hard job for a number of reasons. The most recent evidence-based strategies (such as the cued recall or the spaced retrieval techniques) aim to improve cognitive function at initial stages of the disease, while in more severe stages interventions such as validation therapy are used, which are traditionally adopted, but lack a solid scientific rationale, and often even a consistent evidence-based efficacy. Many studies have been carried out to try demonstrate the effect of these "therapies", or to project new interventions, while little attention has been given to the fact that simple neuropsychological principles keeping into account the nature of the pathological aging observed in dementia can be fruitfully adopted to improve and personalize different kinds of intervention. A rational use of current neuropsychological concepts optimizes the patient's benefit as well as the operator's efforts. A rehabilitative intervention based on current neuropsychological concepts and on awareness of the mechanisms of pathological ageing of cognition provides the possibility of tailored treatments for many different patients, an important reduction of burn-out in the personnel, and clinically relevant outcomes, such as an implicit orientation for the patient, with beneficial effects on mood and behavior.