The validity of the NART-RSPM index in detecting intellectual decline following traumatic brain injury: a controlled study

Lifespan normative data (18-89 years) for Raven's Advanced Progressive Matrices Set I

Raven's Advanced Progressive Matrices (APM) Set I is a validated and brief test of fluid intelligence, ideal for use in busy clinical settings. However, there is a dearth of normative data allowing an accurate interpretation of APM scores. To address this, we present normative data from across the adult lifespan (18-89 years) for the APM Set I. Data are presented in five age cohorts (total N = 352), including two older adult cohorts (65-79 years and 80-89 years), which allows age-standardized assessment. We also present data from a validated measure of premorbid intellectual ability, which was absent from previous standardizations of longer forms of the APM. In line with previous findings, a striking age-related decline was noted, beginning relatively early in adulthood and most marked amongst lower-scoring individuals. Older adults did not demonstrate difficulty with specific test items or make an increased proportion of specific errors. Sex was not a significant predictor of performance. The data set is of particular use in the neuropsychological assessment of older adults, given the known susceptibility of fluid intelligence to both the effects of normal ageing and acquired brain injury in older age. The results are discussed in light of theories of neurological ageing.

Exploration of the Raven APM-National Adult Reading Test discrepancy as a measure of intellectual decline in older persons

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 χ(2) 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.

Is performance on the Wechsler test of adult reading affected by traumatic brain injury?

OBJECTIVES

The validity of the National Adult Reading Test (NART) as a predictor of premorbid IQ when used with patients who have sustained a traumatic brain injury (TBI) has been questioned in recent years. This study examined whether performance on the Wechsler Test of Adult Reading (WTAR) is similarly affected by TBI in the first year after an injury.

DESIGN AND METHOD

The WTAR scores of participants who had sustained a mild TBI (N=82), moderate TBI (N=73), severe TBI (N=61) or an orthopaedic injury (N=95) were compared (cross-sectional study). A subset of 21 mild TBI, 31 moderate TBI, 26 severe TBI and 21 control group participants were additionally reassessed 6 months later to assess the impact of recovery on WTAR scores (longitudinal study).

RESULTS

The severe TBI group had significantly lower scores on the WTAR than the mild TBI, moderate TBI and control groups in the cross-sectional study, despite being matched demographically. The findings from the longitudinal study revealed a significant group difference and a small improvement in performance over time but the interaction between group and time was not significant, suggesting that the improvements in WTAR performance over time were not restricted to more severely injured individuals whose performance was temporarily suppressed.

CONCLUSIONS

These findings suggest that reading performance may be affected by severe TBI and that the WTAR may underestimate premorbid IQ when used in this context, which may cause clinicians to underestimate the cognitive deficits experienced by these patients.

Estimation of premorbid general fluid intelligence using traditional Chinese reading performance in Taiwanese samples

AIMS

The aims of the present study were to (i) investigate if traditional Chinese word reading ability can be used for estimating premorbid general intelligence; and (ii) to provide multiple regression equations for estimating premorbid performance on Raven's Standard Progressive Matrices (RSPM), using age, years of education and Chinese Graded Word Reading Test (CGWRT) scores as predictor variables.

METHODS

Four hundred and twenty-six healthy volunteers (201 male, 225 female), aged 16-93 years (mean +/- SD, 41.92 +/- 18.19 years) undertook the tests individually under supervised conditions. Seventy percent of subjects were randomly allocated to the derivation group (n = 296), and the rest to the validation group (n = 130).

RESULTS

RSPM score was positively correlated with CGWRT score and years of education. RSPM and CGWRT scores and years of education were also inversely correlated with age, but the declining trend for RSPM performance against age was steeper than that for CGWRT performance. Separate multiple regression equations were derived for estimating RSPM scores using different combinations of age, years of education, and CGWRT score for both groups. The multiple regression coefficient of each equation ranged from 0.71 to 0.80 with the standard error of estimate between 7 and 8 RSPM points. When fitting the data of one group to the equations derived from its counterpart group, the cross-validation multiple regression coefficients ranged from 0.71 to 0.79. There were no significant differences in the 'predicted-obtained' RSPM discrepancies between any equations.

CONCLUSION

The regression equations derived in the present study may provide a basis for estimating premorbid RSPM performance.

Neuropsychological and Information Processing Performance and Its Relationship to White Matter Changes Following Moderate and Severe Traumatic Brain Injury: A Preliminary Study

Reductions in information processing speed have frequently been reported following moderate and severe traumatic brain injuries (TBIs), consistent with the effects of diffuse white matter damage. Although the corpus callosum (CC) is a common site for diffuse damage following TBI, the effects of this damage on information processing speed have not been adequately examined. This study assessed a TBI group and a matched control group on tests of attention, memory, fluency, and set shifting ability, together with reaction time (RT) tasks requiring the inter- and intrahemispheric processing of visual and tactile information. The RT tasks were designed to target the cognitive functions that are likely to be affected by diffuse white matter damage, including damage to the CC. The TBI group demonstrated deficits in verbal and visual fluency and verbal memory. They were also slower on the visual and tactile RT tasks, were more affected by task complexity, and slower on RT tasks requiring the interhemispheric transfer of information. In fact, one of the interhemispheric tactile RT tasks proved to be the most discriminating of all the cognitive and RT measures. MRIs completed on a subset of TBI participants indicated that the mean CC measurements were 5% to 19% smaller than a normative control group, with the most atrophied areas being the isthmus and anterior midbody. Although white matter atrophy was moderately related to visual and tactile RT performance, and total hippocampal volume related to memory performance, CC area was not related to many of the tasks that were designed to tap interhemispheric processing. None of the standard cognitive tests correlated with outcome in the TBI group, but 1 of the tactile RT measures was significantly related to 2 measures of outcome.