# Ideational Slippage in Middle-Aged and Older Adults: A Preliminary Study

## TL;DR

This study explores how brain structure relates to communication errors in middle-aged and older adults, suggesting a link to early cognitive decline.

## Contribution

The study introduces a performance-based assessment of ideational slippage linked to corpus callosum volume in aging adults.

## Key findings

- Smaller splenium volume correlates with greater ideational slippage in middle-aged and older adults.
- The association remains significant after controlling for processing speed and fluid intelligence.
- Observed effects support the role of the splenium in visuospatial perception and cognitive function.

## Abstract

Ideational slippage—characterized by incorrect word usage and strained logic during dialogue—is common in aging and, at greater frequency, is an indicator of pre-clinical cognitive decline. Performance-based assessment of ideational slippage may be useful in the study of cognitive aging and Alzheimer’s-disease-related pathology. In this preliminary study, we examine the association between corpus callosum volume and a performance-based assessment of ideational slippage in middle-aged and older adults (age 61–79 years). Ideational slippage was indexed from cognitive special scores using the Rorschach Inkblot Method (RIM), which are validated indices of deviant verbalization and logical inaccuracy (Sum6, WSum6). Among middle-aged and older adults, smaller splenium volume was associated with greater ideational slippage (ηp2 = 0.48), independent of processing speed and fluid intelligence. The observed negative associations are consistent with visuospatial perception and cognitive functions of the splenium. The effect was strongest with the splenium, and volumes of the genu and total white matter had small effects that were not statistically significant. Conclusions: Results are discussed with future application of RIM special scores for the assessment of pre-clinical cognitive decline and, based on observed effect sizes, power analyses are reported to inform future study planning.