Linguistic and Cognitive Complexity from Personal Diaries Predicts Late-life Cognitive Health: the Cache County Journal Pilot Study

Abstract

The aging population throughout the world is increasing, leading to larger numbers of individuals with Alzheimer\u27s disease (AD), with a price tag for services ranging in the hundreds of billions of dollars. The neurodegenerative process of AD may begin decades before symptom onset, prompting studies of early detection and prevention. The cognitive reserve hypothesis posits that cognitive stimulation throughout the lifespan (e.g. from formal education, occupations, leisure activities) builds neuronal connections in the brain that can delay onset of symptoms even once the neurodegeneration has begun. Expressive writing samples have been used to measure linguistic and cognitive complexity, both potential markers for cognitive reserve. The Cache County Memory Study (CCMS) conducted four waves of dementia ascertainment in an initial panel of 5,092 persons aged 65 and older on 1/1/95. In a sample of 67 of these participants (43% males), writing samples from personal journals earlier in life (as early as age 20), were collected and subjected to linguistic analysis using the Linguistic Inquiry Word Count (LIWC) software. Results yielded average Words per sentence (WPS), and Proportion of Words that are Numerals (PWN). Cognitive status at study entry in the CCMS was measured using the Modified Mini-Mental State Exam (3MS; range 0-100). WPS and PWN were correlated with 3MS scores, for the sample overall and separately by gender. For males, higher WPS was significantly correlated with higher 3MS score (r=0.431, p=0.020), and higher PWN was significantly correlated with lower 3MS (r=-0.504, p=.005), but there were no significant correlations for females. Word Count, Percentage of Six-Letter Words, and Percentage of Unique Words were also analyzed, although none of these predicted 3MS score. In conclusion, these results suggest that early adulthood writing samples may be used to predict later dementia risk. Early prediction would allow time for interventions to delay dementia expression