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Test of Premorbid Functioning
Please visit this website for more information about the instrument: Test of Premorbid Functioning
NeuroRehab Supplemental - Highly Recommended
Recommendations for Use: Indicated for studies requiring a measure for premorbid functioning or assessments of premorbid intelligence.
  • It is recommended to use either the Test of Premorbid Functioning (TOPF) or the Word Reading Subtest of the Wide Range Achievement Test (WRAT-4) at baseline. See comments and special instructions.
  • Use is generally recommended for clinical conditions with CNS involvement impacting cognition (especially those with onset after childhood) but not specifically affecting reading (e.g., alexia, dyslexia, aphasias)
Supplemental: Myalgic encephalomyelitis/Chronic fatigue syndrome (ME/CFS), Sport-Related Concussion (SRC)
Short Description of Instrument
The purpose of the TOPF is to estimate preinjury intellectual level based on an individual's ability to read words that lack graphemic-phonemic correspondence (e.g., "yacht"). The TOPF consists of 70 words and takes 10 minutes to administer. The TOPF is currently marketed as a package that includes norms for the WAIS-IV and Wechsler Memory Scale-IV so the user can compare the intellectual level estimated by the TOPF with current level of intellectual function determined by the WAIS-IV. The kit also includes instructions to estimate preinjury intellectual level based on demographic features rather than reading performance.
Comments/Special Instructions
Among many other conditions involving CNS compromise (see above), this assessment is relevant for evaluating neurodegenerative changes during the chronic phase in athletes who have extensive exposure to a contact sport, including multiple concussions and numerous subconcussive head impacts over an extended duration.
NeuroRehab Specific: The Test of Premorbid Functioning is explicitly designed to not be phonologically decoded and more directly measures vocabulary than reading ability while the WRAT phonologically decodes words and is designed to measure reading ability. The other primary difference between the tests is that the Test of Premorbid Functioning was co-normed and calibrated to the exact mean of the Wechsler Adult Intelligence Scale-IV (WAIS-IV). The WRAT is calibrated with a sample starting off at a higher or lower than 100 ability level relative to the mean, and this depends on the version. Test of Premorbid Functioning is preferable, compared to the WRAT, but the WRAT will be included as an alternative due to its legacy status and the amount of existing data collected.
Scoring and Psychometric Properties
Scoring: Number of words correctly read.
Psychometric Properties: Normed on ages 16-90-fully stratified sample representative of the US
Reliability: Internal consistency .96 to .99 (average .98)
Reliability for TBI = .98, MCI=.98, Alzheimers = .99
Retest reliability = .89 to .95
Correlation with WAIS-IV VCI = .75
Correlation with WIAT-II Word Reading = .77
The rationale for the TOPF is based on using recognition of irregular words to estimate preinjury intellectual level. However, this assumption might not be valid in athletes and other individuals whose intellectual abilities were developmentally uneven or who had a learning disability wherein verbal skills were less developed than visuospatial ability.
Strengths:  The TOPF was co-normed with the WAIS-IV/WMS-IV and the scores from the TOPF are calibrated to the norms associated with the IQ and memory measures. No other premorbid estimate is calibrated to the WAIS-IV norms, therefore differences in normative samples, normative methods, and dates of norms will result in scores that are not aligned (e.g., mean of WAIS-IV may be higher or lower than the mean of the measures derived from different samples)
The TOPF provides a series of equations for determining if the TOPF should or should not be used as an estimator. The technical manual provides data regarding the impact of developmental and neurological conditions on reading as a premorbid estimator. Additionally, equations provide statistics for probability of unexpectedly low IQ/Memory versus premorbid estimate.
Weaknesses: Test is owned by Pearson (cost), software is required to score and produce equations. Also, if not using full WAIS-IV, must enter estimated scores to get regression-based estimates.
Wechsler D, ed. Test of Premorbid Functioning. San Antonio, TX: The Psychological Corporation; 2009.
Pearson (2009) Advanced Clinical Solutions for WAIS-IV/WMS-IV Technical Manual. San Antonio, TX: Pearson,
Donders J, Stout J. The Influence of Cognitive Reserve on Recovery from Traumatic Brain Injury. Arch Clin Neuropsychol. 2019;34(2):206-213.
Rolin SN, Davis JJ, Miller JB. Estimating Premorbid Ability in Rehabilitation Patients Using the Test of Premorbid Functioning and Wide Range Achievement Test-Fourth Edition. Assessment. 2021;28(3):994-1003.
Document last updated January 2022