THE BIOLOGY OF INTELLIGENCE - FROM ASSOCIATION TO MECHANISM

Advances in the molecular genetics of the nervous system are important in understanding the nature of human intelligence differences and the ir changes with age. As a case study for such research we discuss rece nt research on apolipoprotein E (ApoE). The gene for ApoE (the APOE ge ne) shows polymorphism in humans. The epsilon 4 allele is associated w ith increased incidence of Alzheimer's disease and lesser forms of cog nitive dysfunction as people grow older. Such cognitive dysfunction ap pears often to be the interaction between possession on the epsilon 4 allele of APOE and brain insults such as head injury, cardiac bypass s urgery and intracerebral haemorrhage. The mechanisms by which the ApoE epsilon 4 isoform might increase the vulnerability of the brain to in sults are presented. Implications for research on human intelligence a re discussed.