The effects of prenatal alcohol exposure on executive functioning

Abstract

Converging evidence from various research areas indicates that people who have been exposed to alcohol prenatally may exhibit impairments on the performance of relatively complex and novel tasks. These tasks include tests designed to measure executive functioning (EF)--the ability to plan and guide behavior to achieve a goal in an efficient manner. EF can be categorized into two domains, cognition-based EF and emotion-related EF. People prenatally exposed to alcohol show impaired performance on tests assessing both domains. Moreover, one cognition-based and two emotion-related measures of EF appear to be reliable and stable predictors of behavioral problems in alcohol-affected people. A deficit in flexible recruitment of brain regions to do complex tasks may underlie the EF deficits in people prenatally exposed to alcohol.

Figure 1

Images of the human brain showing two regions in the prefrontal cortex—the dorsolateral and the orbital—that are critical for cognition-based and emotion-related executive control functioning. Also indicated are other brain regions affected by prenatal alcohol exposure, including the cerebellum, basal ganglia, and corpus callosum. SOURCE: Modified from Color Atlas of the Brain and Spinal Cord, M.A. England and J. Wakely, 1991.

Figure 2

An illustration of two typical problems with different levels of complexity administered as part of the Progressive Planning Test (PPT). In both instances, the subject must move several beads from their initial positions to the goal position. When solving the problem, the subject can move only one bead at a time; once a bead has been moved from its initial position, it cannot be returned to that position. The problems shown here use three beads, each of a different color: yellow (Y), red (R), and blue (B). The first problem (labeled “simple”) has a relatively straightforward solution and, therefore, does not strain the subject’s working memory. The subject must move the beads as follows: the yellow, or Y, bead to the second (or 2) peg (denoted as Y to 2), then R to 2, B to 3, R to 3, and Y to 3. In contrast, the second problem requires greater mental manipulation by the subject, namely reversing the order of two beads (i.e., the Y bead and the R bead) when placing them in the second position before moving the B bead to the goal position. Thus, the subject must accomplish six steps to solve the problem: Y to 3, R to 2, Y to 2, B to 3, Y to 3, and R to 3.