Working memory late effects in survivors of pediatric acute lymphoblastic leukemia

Acute Lymphoblastic Leukemia (ALL) is the most commonly diagnosed malignancy in children (Pui, 2000; Steen & Mirro, 2000; American Cancer Society, 2009; Westlake & Bertolone, 2002). Modern advances in cancer treatment, such as combination chemotherapy (Ettinger, Bond, & Sievers, 2002; Rodman & Reed, 2009), have increased survivorship of ALL to nearly 85% (Westlake & Bertolone, 2002). This new population of ALL survivors is displaying a unique profile of cognitive late effects that are a result of the treatment (e.g. chemotherapy) which while effective in eradicating the disease, has neurotoxic properties (American Cancer Society, 2009). Late effects have been discovered in a variety of cognitive skills, including academic achievement, visual-spatial skills, and processing speed, but the most commonly seen late effects are in the areas of attention and memory (e.g. Askins & Moore, 2008; Cullen, Derrickson, & Potter, 2002; Leigh, 2000). While working memory is a skill that depends on both attention and memory (Baddeley 2000) and is important in both academic performance and life skills (Dark & Benbow, 1991; Geary, Hoard, & Hamson, 1999), it is relatively unstudied in this population. The purpose of this study was to investigate working memory abilities in survivors of pediatric ALL. Working memory skills in this population were compared to both sample and population IQ. Comparisons of verbal and nonverbal working memory and male and female working memory skills were compared as well. First, working memory, as measured by a composite, was not found to be significantly impaired when compared to sample and population mean IQ. However, a single subtest, Digit Span Backward from the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV; Wechsler, 2003), when compared to IQ outside the composite, was found to be significantly below IQ for both the sample and population mean. Second, no gender differences were found for working memory abilities. Finally, there was no difference between nonverbal and verbal working memory performance. While the results were nonsignificant, verbal working memory was worse than nonverbal working memory, which was the opposite of the hypothesized pattern. Implications, recommendations, and limitations of this study are discussed in detail.