Children With Heavy Prenatal Alcohol Exposure Demonstrate Deficits on Multiple Measures of Concept Formation

Fetal Alcohol Syndrome (FAS) is a developmental disorder caused by excessive maternal alcohol consumption during pregnancy, which has long lasting consequences on cognitive, behavioral, and psychosocial functioning in the offspring. It is characterized by a unique pattern of facial dysmorphia, growth retardation, and central nervous system (CNS) dysfunction (Hoyme et al., 2005; Jones and Smith, 1973; Jones et al., 1973). Children with histories of prenatal alcohol exposure, with or without a diagnosis of FAS, often exhibit qualitatively similar deficits on a variety of neuropsychological and behavioral measures (e.g., Mattson et al., 1998). The cognitive and behavioral problems caused by prenatal alcohol exposure likely lead to more significant disability than do the minor facial anomalies required for the diagnosis of FAS. Although the range of behavioral impairments following gestational alcohol exposure is broad, identifying the core deficits and relative strengths and weaknesses associated with prenatal alcohol exposure may lead to improved differential diagnosis. One neuropsychological domain that has received increased attention in this population is executive functioning, which is a complex construct that has been broadly defined as “the ability to maintain an appropriate problem solving set for attainment of a future goal” (Welsh and Pennington, 1988). A variety of cognitive functions are subsumed under this general definition including planning, concept formation, set shifting and set maintenance, inhibition, working memory, problem solving, and the ability to integrate information across time and space (Pennington and Ozonoff, 1996). Deficits have been reported in children with heavy prenatal alcohol exposure in areas of executive functioning including planning, flexibility, fluency, inhibition, concept formation, and reasoning (Kodituwakku et al., 1995; Kopera-Frye et al., 1996; Mattson et al., 1999; Schonfeld et al., 2001). Concept formation is 1 component of executive function that has received limited attention in alcohol-exposed individuals. The ability to form mental categories for objects, events, and ideas is essential for abstract thought and problem solving in everyday life. Formally, concept formation relies on the ability to use prior knowledge to identify abstract concepts that capture common defining properties of a set of stimuli (Hartman and Stratton-Salib, 2007). In addition to the identification of concepts, the majority of tasks designed to assess concept formation are complex and require other cognitive abilities such as selective attention and working memory to focus and shift attention among stimuli features and keep track of concepts already generated. Previous studies have identified deficits on tasks tapping verbal and nonverbal concept formation in individuals with prenatal alcohol exposure. Specifically, alcohol-exposed individuals have more difficulty guessing the correct target word from sentences providing clues of context, structure, and meaning (Mattson et al., 1999) and providing reasonable responses on a numerical estimating task (Kopera-Frye et al., 1996). In the nonverbal domain, children with prenatal alcohol exposure show greater difficulty identifying conceptual rules on the Children’s Category Test (Mattson et al., 1998), and achieve fewer categories and are impaired in their ability to respond to feedback on the Wisconsin Card Sorting Test (WCST) (Carmichael Olson et al., 1998; Coles et al., 1997; Kodituwakku et al., 1995). The first goal of the current study was to evaluate concept formation in a sample of heavily exposed children using 2 well-validated tasks, the WCST and the Card Sorting Test (CST) from the Delis–Kaplan Executive Functioning System (DKEFS). While both of these tasks involve sorting, they place different constraints on concept formation and have different response requirements (as described below). Taken together, they provide information that may be useful in elucidating aspects of concept formation that are most problematic for children with heavy prenatal alcohol exposure. The WCST is a classic test of executive functioning that requires the identification of 3 sorting principles and the flexible application of these rules in response to feedback (Heaton et al., 1993). On this task, individuals are asked to match cards to 4 key cards that have varying numbers of different colored shapes, and are given feedback regarding response accuracy. Once the category (color, shape, or number) is correctly completed, it is changed without notice, and individuals must use feedback to learn the new sorting rule. Overall, reports of WCST performance in children with prenatal alcohol exposure suggest impairments in concept formation and difficulty responding to feedback (i.e., shifting to a new category). Specifically, 3 studies of alcohol-exposed children have revealed deficits on the WCST including increased errors and fewer categories achieved (Carmichael Olson et al., 1998; Coles et al., 1997; Kodituwakku et al., 1995). In contrast, a prospective study of children with lower levels of prenatal alcohol exposure found only a moderate correlation between WCST variables and prenatal alcohol exposure, suggesting that the relationship between prenatal alcohol exposure and concept formation may be dose-dependant (Streissguth et al., 1994). The CST is another measure of concept formation that requires the flexible identification of multiple concepts within sets of stimuli (Delis et al., 1992, 2001). The task involves sorting 6 cards according to various unifying characteristics and requires the recognition of multiple sorting rules and the inhibition of perseverative responses. The CST requires both identification and verbalization of sorting principles following both spontaneous (by the participant) and structured (by the examiner) sorting. The principles differ in level of difficulty and include both verbal (semantic) and nonverbal (perceptual) concepts. In contrast to the WCST, individuals are not provided with feedback on their performance. In a factor analysis of the CST, the WCST loaded heavily on a CST factor related to accuracy of responding (i.e., errors), but was not related to 2 other independent CST factors: one for each of the verbal and nonverbal concept formation domains (Greve et al., 1995). This indicates that the CST provides unique information, and can provide additional information about verbal or nonverbal concept formation relative to the WCST. This may be particularly useful as the WCST may be heavily mediated by verbal skills (Goldstein et al., 1996; Rempfer et al., 2006). To date, no studies using the CST in a prenatally alcohol-exposed sample have been published. The second goal of the current study was to examine the relationship between concept formation and general intellectual functioning in children with heavy prenatal alcohol exposure. Assessment of relative strengths and weaknesses in this population will assist in the definition of a cognitive profile or profiles, which is currently being sought (Riley et al., 2003). Little information exists regarding the relationship of concept formation or other executive function measures to general intellectual function. Although a small number of studies using the WCST exist, only one has attempted to determine the relationship of executive functioning to overall cognitive ability in an alcohol-exposed population (Connor et al., 2000). Performance on a computerized version of the WCST was examined in relation to estimates of IQ in an adult sample with heavy prenatal alcohol exposure. Nonlinear regression lines were computed from a large sample of adults (n = 434), the majority of which were recruited through the Seattle longitudinal prospective study on prenatal alcohol exposure (subjects falling in the highest 10% of exposure levels were excluded). Data from 29 clinically referred adult men with heavy prenatal alcohol exposure were then plotted and compared with the regression lines. For each of the 5 primary WCST variables, 6 to 7 of the heavily exposed subjects performed better than predicted based on regression estimates, whereas 22 to 23 alcohol-exposed subjects did worse than predicted. These results suggest thatWCST performance, at least using the computerized version, may be a relative weakness for adults with heavy prenatal alcohol exposure. However, these results should be interpreted cautiously since the heavily exposed subjects with the lowest IQ scores do not appear to fall within the range of scores used to calculate the regression lines. Regression lines tend to be unreliable when based on few observations (i.e., at the extremes of a distribution) and extrapolation can lead to extraneous results (Cohen et al., 2003; Kuo, 2002). No studies using the CST exist with which to compare results to general intellectual functioning. The current study incorporates tasks that require concept formation for successful performance. While previous studies have examined some areas of concept formation, the tests used in the current study represent a more comprehensive assessment, including both verbal and nonverbal components and a level of detail not available in individual measures. In addition, concept formation was compared to general cognitive functioning to evaluate if concept formation is a relative strength or weakness in this population.