Estimation of premorbid cognitive function based on word knowledge: the Swedish Lexical Decision Test (SLDT)

Area of Science:

• Clinical Neuropsychology
• Cognitive Psychology
• Psychometrics

Background:

• Assessing current patient status requires estimating premorbid cognitive function.
• Existing methods for premorbid status assessment in Sweden are suboptimal.
• Word knowledge is empirically linked to global cognitive functioning in adults.

Purpose of the Study:

• To design and evaluate a Swedish Lexical Decision Test (SLDT) for assessing premorbid global cognitive function (intelligence).
• To establish the psychometric properties of the SLDT in a healthy Swedish population.
• To illustrate the SLDT's utility in a clinical context, including a case of Alzheimer's disease.

Main Methods:

• Development of the Swedish Lexical Decision Test (SLDT) based on word knowledge.
• Linear stepwise regression analysis to determine the predictive power of SLDT for global cognitive function.
• Evaluation of psychometric properties using data from 109 healthy individuals stratified by demographics.
• Case study analysis including an Alzheimer's disease patient.

Main Results:

• SLDT findings explained 48% of the variance in Full Scale Intelligence Quotient (FSIQ) from the Wechsler Adult Intelligence Scale Revised (WAIS-R).
• Demographic variables accounted for 31% of the variance.
• Combining SLDT results with demographic variables accounted for 60% of the variance in FSIQ.
• The study presents psychometric properties and discusses the theoretical basis of the word knowledge-cognition relationship.

Conclusions:

• The SLDT is a promising tool for estimating premorbid intelligence in clinical neuropsychology in Sweden.
• The test demonstrates significant predictive validity for global cognitive function.
• The findings support the strong association between lexical knowledge and general cognitive abilities.