Abstract
Background: To define the profile of age-related differences in cognition in healthy middle-aged adults in order to identify the most sensitive measures of early cognitive decline. To study whether these differences precede cognitive decline in the elderly. Method: 141 cognitively normal participants (101 middle-aged adults with age 40-50±2; and 40 elderly individuals with age 65±2) were assessed with a comprehensive neuropsychological protocol covering processing speed, attention, executive functions, verbal and visual episodic memory, procedural memory, visuoconstructive, visuoperceptive and visuospatial functions, and language. Results: Age-related differences were detected before the age of 50 in cognitive reaction time, executive control, initial learning in verbal episodic memory, complex visuoconstructive and visuospatial functions, and lexical access. These differences preceded more extensive cognitive decline present at the age of 65. Conclusions: Our findings suggest subtle executive dysfunction before the age of 50, together with slowing in processing speed later on in the transition to old age. This profile could be explained by changes in the frontal lobe and its connections, starting at middle-age. These findings, together with future research, may be important for the diagnosis, prognosis, and prevention of pathological aging at a very early level.
