Relation between age-related decline in intelligence and cerebral white-matter hyperintensities in healthy octogenarians: a longitudinal study

Background While-matter hyperintensities are commonly found on magnetic res onance imaging (MRI) of elderly people with or without dementia. Studies of the relation between severity of white-matter hyperintensities and cogniti ve impairment have had conflicting results. We undertook a longitudinal stu dy of age-related decline in intellectual function and MRI at age 80 years. Methods From a cohort of 698 people born in 1914 and living in seven munici palities in Denmark, 68 healthy non-demented individuals had been tested wi th the Wechsler adult intelligence scale (WAIS) at ages 50, 60, and 70, and they agreed to further WAIS testing at age 80, and cerebral MRI at age 80- 82 (mean age 82.3 years). We scored separately the numbers of periventricul ar and deep white-matter hyperintensities. Findings Scores for periventricular hyperintensities in this sample include d all possible degrees of severity, but no participant scored more than 75% of maximum for deep white-matter hyperintensities. Neither type was relate d to the WAIS IQs of the 80-year assessment, but both were significantly as sociated with decline in performance IQ from age 50 to age 80 years (bivari ate correlation coefficients 0.32, p=0.0087, and 0.28, p=0.0227, respective ly). An analysis based on two WAIS subtests showed that the association bet ween white-matter hyperintensities and cognitive impairment was significant only for cognitive decline in the decade 70-80 years. Interpretation Both periventricular and deep white-matter hyperintensities are related to decline in intelligence but, in healthy octogenarians, the c umulative effect of these features alone explains only a small part of the large differences among individuals in age-related decline in intelligence, Interpretation of the presence and severity of white-matter hyperintensiti es in a diagnostic context must be done cautiously.