The NART as an index of prior intellectual functioning: a retrospective validity study covering a 66-year interval

Background. The National Adult Reading Test (NART) is widely used in resear ch and clinical practice as an estimate of pre-morbid or prior ability. How ever, most of the evidence on the NART's validity as a measure of prior int ellectual ability is based on concurrent administration of the NART and an IQ measure. Method. We followed up 179 individuals who had taken an IQ test (the Moray House Test) at age 11 and administered the NART and the Mini-Mental State E xamination (MMSE) at age 77. A subset (N = 97) were also re-administered th e original IQ test. Results. The correlation between NART performance at age 77 and IQ age 11 w as high and statistically significant (r = 0.73; P < 0.001). This correlati on was comparable to the correlation between NART and current IQ, and child hood IQ and current IQ, despite the shared influences on the latter variabl e pairings. The NART had a significant correlation with the MMSE but this c orrelation fell to near zero (r = 0.02) after partialling out the influence of childhood IQ. Discussion. The pattern of results provides strong support for the claim th at the NART primarily indexes prior (rather than current) intellectual abil ity.