This study prospectively examined neuropsychological (NP) functioning associated with adolescent substance use and withdrawal. Participants were youths with histories of substance use disorders (n = 47) and demographically comparable youths with no such lifetime histories (n = 26). They were followed with NP testing and substance involvement interviews at 7 time points spanning 8 years, from ages 16 to 24, on average. After controlling for recent use, age, education, practice effects, and baseline NP functioning, substance use over the 8-year follow-up period significantly predicted performances on tests of memory and attention at Year 8. Additionally, withdrawal symptoms during the follow-up predicted visuospatial and attention scores at Year 8. Findings suggest that use and withdrawal may differentially impact neurocognitive functioning during youth, with heavy use leading to learning, retention, and attentional difficulties, and withdrawal leading to problems with visuospatial functioning. (JINS, 2002, 8, 873–883.)

Alcohol and other drug use are common in youth, but neurocognitive sequelae are unclear. This study examines the relationship between neuropsychological functioning and protracted substance use in adolescence. One hundred fifteen adolescents, ages 13 to 19 years, were recruited from inpatient substance abuse treatment programs and followed for 4 years. Adolescents were administered a comprehensive battery of neuropsychological tests and evaluated on substance use involvement during treatment, and at 6-month, 1-year, 2-year, and 4-year follow-up time points. Protracted substance abuse over the 4 years of follow-up was associated with significantly poorer subsequent functioning on tests of attention. In addition, alcohol and drug withdrawal accounted for significant variance in visuospatial functioning, above and beyond demographic, educational, and health variables in detoxified late adolescents and young adults. Results suggest that alcohol and drug withdrawal may be a more powerful marker of protracted neuropsychological impairments than other indices of youthful alcohol and drug involvement. (JINS, 1999, 5, 481–493.)

Face recognition is often considered to be a modular (encapsulated) function. This annotation supports the proposal that faces are special, but suggests that their identification makes use of general-purpose cortical systems that are implicated in high-level vision and also in memory and learning more generally. These systems can be considered to function within two distinct cortical streams: a medial stream (for learning and salience of faces encountered) and a lateral stream (for distributed representations of visual properties and identities of faces). Function in the lateral stream, especially, may be critically dependent on the normal development of magnocellular vision. The relevance of face recognition anomalies in three developmental syndromes (Autism, Williams syndrome, and Turner syndrome) and the two-route model sketched above is considered.

Williams syndrome (WS) is a rare genetic disorder which, among other characteristics, has a distinctive cognitive profile. Nonverbal abilities are generally poor in relation to verbal abilities, but also show varying levels of ability in relation to each other. Performance on block construction tasks represents arguably the weakest nonverbal ability in WS. In this study we examined two requirements of block construction tasks in 21 individuals with WS and 21 typically developing (TD) control individuals. The Squares tasks, a novel two-dimensional block construction task, manipulated patterns by segmentation and perceptual cohesiveness to investigate the first factor, processing preference (local or global), and by obliqueness to examine the second factor, the ability to use mental imagery. These two factors were investigated directly by the Children's Embeded Figures Test (CEFT; Witkin, Oltman, Raskin, & Karp, 1971) and a mental rotation task respectively. Results showed that individuals with WS did not differ from the TD group in their processing style. However, the ability to use mental imagery was significantly poorer in the WS group than the TD group. This suggests that weak performance on the block construction tasks in WS may relate to an inability to use mental imagery.

Previous twin and family studies have indicated that there are strong genetic influences in the etiology of autism, and provide support for the notion of a broader phenotype in first-degree relatives. The present study explored this phenotype in terms of one current cognitive theory of autism. Parents and brothers of boys with autism, boys with dyslexia, and normal boys were given tests of “central coherence”, on which children with autism perform unusually well due to an information-processing bias favouring part/detail processing over processing of wholes/meaning. Results indicated that fathers of boys with autism, as a group, showed piecemeal processing across four tests of central coherence. This was not true for any other group. These findings raise the possibility that the broader autism phenotype may include a “cognitive style” (weak central coherence) that can confer information-processing advantages.

One commonly cited feature of Williams syndrome is a characteristic dissociation between relatively spared language skills and severely impaired nonverbal abilities. However, the actual evidence for a dissociation between verbal and nonverbal abilities in Williams syndrome is equivocal. In two separate studies we examined these abilities in 16 individuals showing the Williams syndrome phenotype. When considered as a whole, the group did have significantly superior verbal abilities, but this difference was caused by a large discrepancy in abilities in only a small number of individuals. In both studies there was a clear, linear relation between individuals' verbal ability, and the magnitude of their verbal–nonverbal discrepancy. We suggest that these results are best explained in terms of verbal ability developing at a faster rate than nonverbal ability in this disorder. We discuss how this model of differential rates of development has the potential to reconcile the apparently inconsistent findings in this area.