Exploration of the Raven APM–National Adult Reading Test Discrepancy as a Measure of Intellectual Decline in Older Persons

Abstract

Previous studies have shown that the discrepancy between performance on “fluid” and “crystallized” intelligence measures may serve as an indicator for intellectual decline. The validity of this procedure in older persons is unknown. The present study developed a multiple regression equation, to predict the Raven Advanced Progressive Matrices (APM) score from the National Adult Reading Test (NART) score and demographic variables in a large sample of healthy older persons (n = 270). The discrepancy between the predicted and observed Raven APM scores was transformed into a percentile distribution as an indicator of intellectual decline, which can be used in clinical practice. The validity of the procedure was further examined by comparing the proportion of persons with a significant decline (at the −1 and −1.65 SD level) between two older patient samples (87 patients with cerebral stroke and 387 patients with diabetes mellitus) by means of χ² tests. There was a significantly higher rate of intellectual decline at the −1 SD (“below average”) and −1.65 SD (“impaired”) cutoff levels for patients with stroke compared with patients with diabetes (stroke, 34% and 14%; diabetes, 16% and 5%, p < .05). These findings suggest that the Raven APM–NART discrepancy may be a useful measure of intellectual decline in older persons.

Key words:

• cognitive decline
• diabetes
• intelligence
• National Adult Reading Test
• norms
• Raven Advanced Progressive Matrices
• stroke

ACKNOWLEDGEMENTS

The authors report no conflict of interest. E.vdB. and A.M.A.B. were supported by Grant No. 2001.00.023 and 2003.01.004 of the Dutch Diabetes Research Foundation. R.P.C.K. was supported by a 2006 Utrecht University High Potential research grant. G.M.S.N. and M.vZ. were supported by the Netherlands Heart Foundation (NHS 2000.023) and the Brain Foundation (The Netherlands). The ADDITION Study in the Netherlands was funded by grants from Novo Nordisk Netherlands, GlaxoSmithKline Netherlands, and Merck Netherlands.

The authors would like to thank P. de Kort and B. Jansen for enrollment of patients in the stroke study. We also thank the Hoorn Study Group (project leaders: J. M. Dekker, Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam; G. Nijpels, Department of General Practice and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam; C. D. A. Stehouwer, Department of Internal Medicine and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands), the Utrecht Diabetic Encephalopathy Study Group (project leader: G. J. Biessels, Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands), the ADDITION Study Group (project leader: G. E. H. M. Rutten, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands), the “Utrecht Diabetes Programma,” and the “IJsselstein Diabetes Project” (mentor: Ph. L. Salomé) for their assistance.

Notes

APM = Advanced Progressive Matrices; NART = National Adult Reading Test; SAT = Spatial Anticipation Test; RAVLT = Rey Auditory Verbal Learning Test; TMT = Trail-Making Test; CI = confidence interval.

^a Raw score of the NART was converted to IQ score based on Dutch normative data.

^b Higher scores reflect worse performance.

APM = Advanced Progressive Matrices; NART = National Adult Reading Test.