Cytomegalovirus infection and cognitive abilities in old age.

Cytomegalovirus infection has been implicated in cognitive impairment in studies using brief clinical assessments though findings are inconsistent. The association between cytomegalovirus infection, measured as serostatus or a semiquantitative assessment of antibody level, and cognitive abilities in a sample of older adults was examined. Cytomegalovirus status was assessed at a mean age of 70 years in 1061 participants of the Lothian Birth Cohort 1936. Cognitive ability scores were available for general cognitive ability, processing speed, memory, and vocabulary. Background demographic and environmental factors included father's social class, years of education, childhood cognitive ability, overcrowding in childhood, and access to indoor toilet facilities. Cytomegalovirus seropositive individuals had lower cognitive ability at age 70: mean IQ was 99.1 (SD, 15.1) versus 102.4 (SD, 13.1) in seronegative individuals (t = 3.65; p < 0.001). The likelihood of contracting cytomegalovirus infection by age 70 was predicted by a number of demographic and environmental factors and, after accounting for these, cytomegalovirus infection (considered as serostatus) was not cognitively detrimental. Within cytomegalovirus seropositive individuals, however, higher cytomegalovirus antibody levels were associated with lower general cognitive ability.