Objective: To determine if linguistic ability in early life is associated with cognitive function and Alzheimer's disease in late life.
Design: Two measures of linguistic ability in early life, idea density and grammatical complexity, were derived from autobiographies written at a mean age of 22 years. Approximately 58 years later, the women who wrote these autobiographies participated in an assessment of cognitive function, and those who subsequently died were evaluated neuropathologically.
Setting: Convents in the United States participating in the Nun Study; primarily convents in the Milwaukee, Wis, area.
Participants: Cognitive function was investigated in 93 participants who were aged 75 to 95 years at the time of their assessments, and Alzheimer's disease was investigated in the 14 participants who died at 79 to 96 years of age.
Main outcome measures: Seven neuropsychological tests and neuropathologically confirmed Alzheimer's disease.
Results: Low idea density and low grammatical complexity in autobiographies written in early life were associated with low cognitive test scores in late life. Low idea density in early life had stronger and more consistent associations with poor cognitive function than did low grammatical complexity. Among the 14 sisters who died, neuropathologically confirmed Alzheimer's disease was present in all of those with low idea density in early life and in none of those with high idea density.
Conclusions: Low linguistic ability in early life was a strong predictor of poor cognitive function and Alzheimer's disease in late life.