INTELLECTUAL-FUNCTIONING IN OLD AND VERY OLD-AGE - CROSS-SECTIONAL RESULTS FROM THE BERLIN AGING STUDY

This study documents age trends, interrelations, and correlates of int ellectual abilities in old and very old age (70-103 years) from the Be rlin Aging Study (N = 516). Fourteen tests were used to assess 5 abili ties: reasoning, memory, and perceptual speed from the mechanic (broad fluid) domain and knowledge and fluency from the pragmatic (broad cry stallized) domain. Intellectual abilities had negative linear age rela tions, with more pronounced age reductions in mechanic than in pragmat ic abilities. Interrelations among intellectual abilities were highly positive and did not follow the mechanic-pragmatic distinction. Sociob iographical indicators were less closely linked to intellectual functi oning than sensory-sensorimotor variables, which predicted 59% of the total reliable variance in general intelligence. Results suggest that aging-induced biological factors are a prominent source of individual differences in intelligence in old and very old age.