Academic journal article New Zealand Journal of Psychology

Is the Test of Premorbid Functioning a Valid Measure for Maori in New Zealand?

Academic journal article New Zealand Journal of Psychology

Is the Test of Premorbid Functioning a Valid Measure for Maori in New Zealand?

Article excerpt

There is an abundance of research indicating culture influences performance on neuropsychological tests (Brickman Cabo, & Manly, 2006), with disparities in test scores between majority and minority cultures (Brickman et al., 2006; Kaufman, McLean, & Reynolds, 1988; Razani, Murcia, Tabares, & Wong, 2006). This has relevance for Maori in New Zealand (NZ) as, while Maori comprise 15% of the population (Statistics New Zealand, 2013a), they are disproportionately more likely to be referred for a neuropsychological assessment than their Pakeha European counterparts (Dudley, Wilson, & Barker-Collo, 2014), with much higher rates of traumatic brain injury (Feigin, Theadom, Barker-Collo, Starkey, McPherson, Kahan, & Ameratunga, 2013) and stroke (Harwood, 2010). In NZ, inequity persists as a result of the "import and drop" approach to neuropsychological assessment (Ogden, 2001; Ogden, Cooper, & Dudley, 2003). While tests that were developed and normed overseas are used to assess, diagnose and plan rehabilitation for Maori clients (Ogden, 2001; Ogden et al., 2003); these tests are culturally bound and inaccurate when applied cross-culturally (Ardila, 1995; Brickman, et al, 2006). A potential result of this is misdiagnosis, inappropriate rehabilitation, and inappropriate financial compensation awarded (Ogden, 2001; Ogden et al., 2003).

In the few studies conducted, Maori perform more poorly than Pakeha on tests that rely on Western education and content, and Maori Perform better than Pakeha on tests that measure visuospatial abilities or on tests that have been adapted to include culturally relevant content (Ogden & McFarlane-Nathan, 1997; Ogden et al., 2003). One aspect of neuropsychological assessment, the assessment of premorbid functioning (PF), is of particular importance. Premorbid, or pre-injury functioning is the estimate of an individuals' level of functioning prior to injury/disease onset, and provides a baseline against which their current performance is compared. In most cases PF must be estimated, and specific tests have been designed to produce these estimates. Valid and reliable tests of premorbid ability should correlate highly with intelligence and be resilient to the effects of brain damage (Crawford, Stewart, Cochrane, Foulds, Besson, & Parker, 1989; Crowell, Vanderploeg, Small, Graves & Mortimer, 2002).

Overseas studies of word reading tests typically report that at least 50-60% of the variance in Full scale IQ scores (FSIQ) is explained. For example, Crawford, Deary, Starr and Whalley, (2001) who followed up 179 individuals who had completed an IQ test at age 11 and administered the National Adult Reading Test (NART; Nelson & Willison, 1991) at age 77). The NART consists of a list of 50 unrelated, phonetically irregular words of graded difficulty which must be read aloud, with scoring based upon correct pronunciation. Performances on the NART and IQ were highly correlated (r = 0.73), accounting for 53% of variance. When applying Japanese and Spanish versions of the NART up to 70% of variance in IQ has been explained (Matsuoka, Masatake, Kasia, Koyama, & Kim, 2006; Schrauf, Weintraub, & Navarro, 2006). For example, Matsuoka et al in a normal elderly population (n = 50) compared a Japanese version of the NART (the JART) with the revised Wechsler Adult Intelligence Scale (WAIS; Wechsler, 1997), finding that the JART explained 61% of variance in IQ scores. These authors further reported that JART-predicted IQs were not significantly different between the normal elderly and age, gender and education matched participants with Alzheimer's disease.

Ogden et al. (2003) were the first to look at the premorbid estimation in a Maori sample, examining the Spot the Word (STW) test (Baddley, Emslie, & Nimmo-Smith, 1993).; a test in which the individual must identify which is the real word from a series of 60 pairs of real and made-up words (Baddeley, Hazel, & Nimmo Smith, 1992) . …

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