The increase in life expectancy at birth, the prolongation of geriatric age and cognitive problems have physical and mental disability processes in common, without these being characteristic of ageing; however, they constitute a challenge for the neurosciences to achieve preventive actions from early stages of life, and thus a healthy and happy life stage. The new paradigms of neurosciences lead us to think that the conceptualisation must be regularly reviewed in the concrete historical context and its analysis must be crossed by the new scientific advances in the subject of dementias vs. major or minor cognitive disorder, as well as the evolutionary construct of cognitive impairment, within the framework of ageing.