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Estimating Premorbid Intelligence



Clin Neuropsychol 2000 Aug;14(3):325-40
Limited accuracy of premorbid intelligence estimators: a demonstration of regression to the mean.

Basso MR, Bornstein RA, Roper BL, McCoy VL.

Department of Psychology, University of Tulsa, OK 74104-3189, USA.

Regression-based premorbid intelligence estimators have been devised by Barona, Reynolds, and Chastain (1984), Barona and Chastain (1986), Hamsher (1984), Krull, Scott, and Sherer (1995; the Oklahoma Premorbid Intelligence Estimate: OPIE), and Vanderploeg, Schinka, and Axelrod (1996; BEST-3 approach), but little is known of their relative accuracy, particularly in outer ranges of intellectual ability (e.g., below-average, superior, etc.). Towards this end, the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was administered to 150 neurologically normal adults, and estimated VIQ, PIQ, and FSIQ scores were computed according to each regression method. Results showed that methods based solely on demographic factors were most susceptible to meanward regression, rendering them poor estimators of IQ scores in outer ranges. Although the OPIE and BEST-3 performed somewhat better, their accuracy remained relatively weak. The findings suggest that regression-based estimates of premorbid IQ are very susceptible to error, particularly in outer ranges of intellectual function.


 J Clin Exp Neuropsychol 1999 Jun;21(3):368-74
WAIS-R prediction equations in patients with traumatic brain injury.

Axelrod BN, Vanderploeg RD, Rawlings DB.

John D. Dingell Department of Veterans Affairs Medical Center, Detroit, MI, USA.

Arithmetic algorithms for predicting premorbid Full Scale IQ were evaluated in a sample of 125 brain injured adults who had been evaluated within two months of their injury, and then again one year later. FSIQ at post-test was used as the criterion variable. The prediction equation, based on demographic information only (Barona, Chastain, & Reynolds, 1984), proved to be a modest predictor of premorbid FSIQ. The BEST-3 (Vanderploeg & Schinka, 1995), a prediction equation that incorporates demographic information and performance data, was sensitive to the severity of the brain injury. Subsequent analyses found the BEST-3 to be a better predictor of recovery of function than it was an estimate of premorbid functioning. This study demonstrates the need for flexibility in the interpretation of results, as what was thought to be a prediction equation for premorbid functioning was better viewed as an estimate of recovery.


J Clin Psychol 1997 Nov;53(7):647-56 
Estimating premorbid WAIS-R intelligence in the elderly: an extension and cross validation of new regression equations.

Paolo AM, Ryan JJ, Troster AI.

University of Kansas Medical Center, Kansas City 66160, USA.

Recently developed equations that combine WAIS-R subtests and demographic information to estimate premorbid intelligence were evaluated in persons 75 years and older. The equations underestimated the obtained IQs of elderly persons. Therefore, new equations were developed using the old age WAIS-R standardization sample. The new equations cross-validated well and demonstrated adequate ability to detect possible intellectual deterioration in a brain damaged sample. The demographic formulas of Barona, Reynolds, and Chastain worked as well as the new equations in suggesting possible deterioration in a sample of elderly persons with chronic and diffuse cognitive impairment.


J Clin Psychol 1996 May;52(3):335-43
Utility of the Barona demographic equations to estimate premorbid intelligence: information from the WAIS-R standardization sample.

Paolo AM, Ryan JJ, Troster AI, Hilmer CD.

Department of Neurology, University of Kansas Medical Center, Kansas City 66160-7314, USA.

The WAIS-R (Wechsler, 1981) and elderly WAIS-R standardization samples (Ryan, Paolo, & Brungardt, 1990) were combined to evaluate the utility of the Barona demographic regression equations (Barona, Reynolds, & Chastain, 1984) to estimate premorbid intelligence. The equations underestimated ability for persons with IQs less than 80 and overestimated ability of subjects with IQs greater than 119. The equations also overestimated the IQs of 247 persons with confirmed brain dysfunction. Because this overestimation occurred for impaired persons with IQs less than 90, it is difficult to determine whether the difference reflects true intellectual deterioration or statistical artifact. Abnormal cut-off scores at the 10% and 5% levels are provided to allow clinicians to detect abnormal discrepancies between the estimated and obtained IQs.


The Clinical Neuropsychologists 2000 14(2):181-186
PPVT-R as an Estimate of Premorbid Intelligence in Older Adults.

Snitz BA, Bieliauskas LA, Crossland A, Basso MR, Roper B.

The Peabody Picture Vocabulary Test-Revised (PPVT-R) was examined as an estimate of premorbid intelligence in a clinical sample of elderly patients (N = 150) undergoing clinical neuropsychological evaluation. PPVT-R standard scores were compared across grossly cognitively intact, mildly/moderately and severely impaired groups of patients, and compared to a short form of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and the Barona regression equation. Results indicate that, while the PPVT-R is vulnerable to increasing levels of cognitive impairment among patients with fewer years of education, the PPVT-R is stable across mild to moderate levels of impairment for patients with greater than 12 years of education. In a sub-sample of grossly cognitively intact patients (n = 91), the PPVT-R standard score correlated significantly with estimated WAIS-R FSIQ (r = .61). Compared to the Barona equation, the PPVT-R was less likely to over-estimate WAIS-R FSIQ in the grossly cognitively intact patients. These data suggest the PPVT-R to be a useful estimate of premorbid ability for patients with a greater than high-school education.

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