The temporal stability of premorbid intelligence: A non-clinical 10-year follow-up study using the Irregular Word Reading Test (TeLPI)

Introduction: The Cognitive Reserve (CR) describes the brain's ability to actively cope with neurological damage, enabling the maintenance of premorbid cognitive functioning through compensatory processes. The most common way to estimate CR is through formal education, the intelligence quotient (IQ) and participation in cognitive stimulating activities. In the absence of IQ data, the Irregular Word Reading Test (TeLPI) allows you to estimate the premorbid intelligence. Objective: The comparison of the TeLPI results between two times of assessment (baseline and re-assessment) with an interval time (IT) of 9 years. To analyze of the stability of their results as a valid dimension for the CR estimation. Results: The TeLPI presented temporal stability of its results between the two evaluation times (IT = 9.07 +/- 1.02). The sample, composed by 63 cognitively healthy participants, showed no differences for the estimated Full Scale IQ (t(62) = 0.49, p = .63), for the Estimated Verbal IQ (t(62) = 0.71, p = .48) and for the estimated Performance IQ (t(62) = 0.64, p = .52). Likewise, no differences were found in the number of TeLPI errors at the two assessment times (t(62) = -0.61, p = .54). Conclusions: Considering that CR is characterized as being relatively stable, the TeLPI should be included in its assessment, as an indicator with proved stability over a long period of time, on the physiological aging spectrum.