Abstract
Introduction: The Free-Cog is a brief cognitive test designed to capture decline in both general cognition and executive function. The Free-Cog has been validated by comparison with the Mini-Addenbrooke Cognitive Examination in a UK secondary care setting. Here, we compare Free-Cog to the routinely-used Mini-Mental State Examination (MMSE) and the Lawton-Brody Instrumental Activities of Daily Living (IADL) and Physical Self-Maintenance Scales (PSMS).
Methods: Patients from three memory clinics were recruited (n=318 records). The Free-Cog, MMSE, IADL and PSMS were administered in-person (n=288), via telephone (n=17), or virtually using video conferencing (n=12). The four tests were compared using Pearson correlation and ability to discriminate based on dementia diagnosis using binary logistic regression and area under receiver operator characteristic (AUROC) curves.
Preliminary results: In-person Free-Cog score correlations ranged from strong (MMSE; r=0.86, 95% Confidence Interval [CI]: [0.83-0.89], p<0.001), to moderate (IADL; r= 0.57, 95% CI: [0.48-0.65], p<0.001) to weak with the PSMS (r=0.28, 95% CI: [0.16-0.39], p<0.001). The Telephone Free-Cog only correlated significantly with MMSE (r=0.73, 95% CI: [0.39-0.90], p<0.001) and virtual Free-Cog with MMSE (r=0.92, 95% CI: [0.74-0.98], p<0.001) and IADL (r= 0.63, 95% CI: [0.09-0.88], p=0.03). Each 1-point increase in Free-Cog (Odds ratio [OR]: 0.75, 95% CI: [0.69-0.82], p<0.001) decreased the odds of being diagnosed with dementia, as the MMSE (OR: 0.66, 95%CI: [0.57-0.76], p<0.001), and IADL (OR: 0.70, 95% CI: [0.60-0.83], p<0.001). The MMSE (AUROC=0.82) followed by the IADL (AUROC=0.80), then Free-Cog (AUROC=0.79) best discriminated between dementia and diagnosed otherwise, whereas the PSMS was inadequate (AUROC=0.60).
Conclusion: The Free-Cog appears to be a free-of-cost, valid alternative to the routinely-used MMSE, and supplements the IADL scale in capturing cognitive and functional changes associated with neurodegenerative diseases of cognition.