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We explored age-related differences in executive function during selection of a target from among active representations. Refreshing (thinking briefly of a just-activated representation) is an executive process that foregrounds a target relative to other active representations. In a behavioral study, participants saw one or three words, then saw a cue to refresh one of the words, saw one word again and read it, or read a new word. Increasing the number of active representations increased response times (RTs) only in the refresh condition for young adults but increased RTs equally in all conditions for older adults, suggesting that they experienced interference from activated irrelevant information during perception and reflection. Consistent with this interpretation, in a functional magnetic resonance imaging study, young adults showed two areas of the left dorsolateral frontal cortex and a medial area of frontal cortex, including anterior cingulate, that were relatively more sensitive to number of active representations during refresh than read trials; for older adults these areas were equally sensitive to number of active items for refresh and read trials. Young and older adults showed activity associated with refreshing on trials requiring selection in left mid-ventral frontal cortex (an area associated with selection from active representations); older adults also showed activity in left anterior ventral frontal cortex (an area associated with controlled semantic activation). Our results support the hypothesis of an age-related decrease in ability to gate out activated but currently irrelevant information, and are consistent with a dissociation of function between left mid-ventral and left anterior ventral frontal cortex.

Using functional magnetic resonance imaging (fMRI) and a working memory procedure, we compared source memory judgments (format and location) with old-new judgments in young and older adults. Consistent with previous fMRI findings, for young adults, an area of left dorsolateral prefrontal cortex showed greater activity during format than old-new judgments made immediately, as well as those made after a brief, filled delay. In contrast, for older adults, activity in this area was not greater during format than old-new judgments at either retention interval. These data provide additional evidence that left lateral prefrontal cortex is important in monitoring specific source information and new evidence that older adults' source memory deficits may be related, in part, to reduced function of this brain area.

Older adults are slower than young adults to think of an item they just saw, that is, to engage or execute (or both) the simple reflective operation of refreshing just-activated information. In addition, they derive less long-term memory benefit from refreshing information. Using functional magnetic resonance imaging (fMRI), we found that relative to young adults, older adults showed reduced refresh-related activity in an area of dorsolateral prefrontal cortex (left middle frontal gyrus, Brodmann's Area 9), but not in other refresh-related areas. This provides strong evidence that a frontal component of the circuit that subserves this basic cognitive process is especially vulnerable to aging. Such a refresh deficit could contribute to poorer performance of older than young adults on a wide range of cognitive tasks.

The total number of American blacks aged 65 years and over is estimated to be approximately 2.3 million, and the black elderly population will continue to increase faster than the white elderly population throughout the remainder of this century. During the period 1985 to 2025, the elderly population in the United States will increase to 105 percent.The prevalence of hypertension and diabetes for the elderly population (65 years and over) is much higher in blacks than in whites. During the period 1976 to 1980, 76.5 percent of black women aged 65 to 74 years had definite hypertension, compared with 53.4 percent of white women.Many factors are associated with the development of hypertension and diabetes in blacks. Specfic epidemiologic studies are necessary to identify black-white differences in risk factors, including biomedical risk, socioeconomic status, psychosocial risk, nutritional status, lifestyle, and genetic factors.