The purpose of this chapter is to summarize current knowledge about the brain bases of the psychological effects of sickle cell disease (SCD). For the purpose of this chapter, we categorize two broad approaches commonly used to identify the behavioral correlates of brain function. Psychological or behavioral models are used that have been developed independent of the study of the nervous system. A common example of this approach is psychoeducational assessment, which focuses on constructs relevant to functional outcomes such as IQ scores and academic skills. Psychological models are also used for assessments that have been derived more directly from neuroscience. This approach typically involves assessing specific neurocognitive domains derived from theories of brain organization, such as language, visual-spatial, and executive functions. SCD offers a challenge to neuropsychologists because of the multiple factors to consider for understanding brain function. Because SCD is a genetic condition present from birth, the disease is likely to interact with developmental factors in infancy or early childhood. Because of social-historical factors, individuals with SCD are more likely than the general population to grow up in difficult social and economic conditions that place them at higher risk for some adverse brain effects. The disease itself also has specific effects on the brain that may lead to acquired brain injury during childhood or later in life. This context creates a challenge; there are multiple potential routes for brain effects that could have an impact on psychological functioning throughout the life span. We discuss research to date on a number of these factors, including pregnancy and birth risks, social and environmental factors in early childhood, and more direct effects of the disease on the brain. These factors are discussed in their likely order of impact based on current research, with direct effects of SCD on the brain having the most robust and well-established effects on neuropsychological functioning. An overview is presented in table 24-1. Mothers of children born with SCD either have SCD or trait. Data on pregnancy outcomes of mothers with SCD or trait indicate that most of these pregnancies are successful and without serious complications (Koshy, 1995; Sun, Wilburn, Raynor, & Jamieson, 2001).
The Participation of Microglia in Neurogenesis: A Review
