Age, gender, general intelligence and educational level influences on working memory

Working memory plays an important role in normal functioning, and its deficits are central to a number of psychiatric and neurological conditions. Working memory functioning appears to be influenced by a number of demographic factors, including age, gender, as well as educational level and general intelligence. The current study examined the effects of age on working memory changes in younger adults, and investigated relative contributions of gender, education and general intelligence on working memory ability. The current study also addressed the ambiguity in the definition of working memory function by employing a multimeasure battery of tasks, assessing several components of working memory both across the verbal and visual-spatial domains. Data were collected from normal adults (N=403) age 18 to 55 who were tested at the Biopsychiatry department of New York State Psychiatric Institute. Working memory measures included a test of visual spatial maintenance (Spatial Delayed Response task), a test of continuous updating (N-Back test), a test of memory for temporal order (Word Serial Position Test) and a test of mental manipulations within working memory (Letter-Number Sequencing). General intelligence was estimated using the Vocabulary subtest of WAIS-III. The results indicate that working memory declines linearly with age in normal adults between ages 18 and 55. Higher levels of estimated intelligence were predictive of better working memory performance and were also found to be a mediating factor for the effects of age on the performance of the measure of continuous updating (N-Back task), such that the age associated decrements were more pronounced in those with lower estimated level of intelligence. In individuals with high estimated intelligence, age was found not to be a significant predictor of performance. After controlling for age, gender and general intelligence, education was a significant predictor of working memory performance on selected measures, including the verbal continuous updating task; however, education did not present as a mediating factor for the effects of age. Gender was found to be a significant predictor only on a test of visual spatial working memory, with males performing better than females.