cortex plays a key role in the ability to maintain and manipulate information in working memory (Cohen et al., 1997; D’Esposito et al., 1995). This ability contributes to many aspects of decision making, such as tracking and integrating various features in order to make an overall evaluation. Working memory abilities may also be important for speculating about possible future outcomes, since such speculation often involves considering and integrating many different pieces of information.
With age, the volume of the brain declines at a rate of about 2 percent per decade (Raz, 2000). This decline in volume appears to be mostly the result of cell shrinkage and reductions in neural connections (Uylings, West, Coleman, De Brabander, and Flood, 2000). The neuron loss that does occur is selective, affecting some regions of the brain but not others. The region hardest hit by aging is the prefrontal cortex (Coffey et al., 1992; Cowell et al., 1994; DeCarli et al., 1994; Raz, 2000; Raz et al., 1997; Tisserand and Jolles, 2003; West, 1996). Although researchers do not yet fully understand why aging affects the prefrontal cortex more than other regions, it seems related to the later development of this region (Raz, 2000). Frontal regions continue to change and develop long after childhood is over (Bartzokis et al., 2003). But the benefits of such plasticity appear to come with a cost. In particular, myelination in the frontal regions has properties that allow it to continue developing into middle age but that may also make it more vulnerable to aging (Bartzokis et al., 2003). In addition, vascular disorders associated with aging, such as hypertension, appear to have more negative consequences for frontal regions than for other brain areas (Raz, Rodrigue, and Acker, 2003). Researchers have attributed many of the cognitive changes seen in normal aging to changes in the prefrontal cortex (Daigneault and Braun, 1993; Moscovitch and Winocur, 1995; West, 1996). Given the marked deficits in decision making seen in patients who have prefrontal (specifically orbitofrontal) lesions, like Phineas Gage, we might also expect to see changes in decision processes with age.
However, behaviorally, older adults could hardly look more different from patients with lesions in orbitofrontal regions. Unlike such patients, older adults in general do not have problems regulating their emotions or social behavior. In fact, as previously noted, older adults are generally better at avoiding negative affect and emotional outbursts than younger adults (Carstensen et al., 2000; Gross et al., 1997; Lawton et al., 1992). This suggests that not all functions subserved by prefrontal regions decline with age.
Although most studies investigating how aging affects prefrontal brain regions have not distinguished its subregions, behavioral data suggest that