Frontal lobe/executive system (FLEX) functional decline associated with age: A meta-analysis of normative neuropsychological studies

Miles Alan Tarter (2000)

Using multiple and redundant electronic and manual search techniques, studies reporting normative data on frontal lobe/executive (FLEX) system functioning in older adults were collected for literature review, meta-analyses and synthesis. Study selection was made on the basis of multiple search techniques in order to gather as complete a collection of primary data as possible without regard to study quality or year of publication. Specific effort was made to locate older studies in order to enable evaluation of possible cohort effects on estimates of decline in FLEX system functioning. Eighty primary studies published from 1941-1998 reporting data on at least one FLEX measure in adults were selected and coded for meta-analyses. Demographic and health data on "normal" subjects was coded for each study. Health of subjects was rated on a 3-point scale based on the stated intent of investigators and descriptions of subjects provided within studies. Study quality was measured by coding whether investigators inquired into 16 areas of health functioning when assembling normal or control subjects. Information on selection strategies and methods was coded and collected. All coding was recorded and organized in a computerized database for meta-analyses. This dissertation has three primary objectives. First, to review and synthesize the literature regarding age related decline in FLEX system functioning in adults and normal elderly subjects. Second, to provide meta-analytic effect size estimates of five subject variables (age, education, gender, health status, and cohort) on performance of commonly used standardized tests sensitive to executive system dysfunction in normal older adults. Third, to provide meta-analytic effect size estimates of three potential sources of systematic, between-studies variance (sample size, sampling method, and sampling strategy) on effect size estimates of aging.