of dementia). Next, a more detailed description of the relation of hypertension and other cardiovascular diseases to cognition is provided. Methodological and conceptual challenges to this field of research are discussed, and future research directions are enumerated.
In general, the investigations described in this paper utilized clinical neuropsychological tests to measure cognitive functioning. These tests can be grouped according to the major domain of cognitive functioning assessed and include measures of attention, learning and memory, executive functions, visuospatial and visuoconstructional skills, psychomotor abilities, perceptual skills, and language functions. Screening tests such as mental status examinations and composite measures such as intelligence tests were also used. The interested reader is referred to Lezak (1995) for a detailed discussion of this particular taxonomy of tests. In addition, an appendix at the end of this paper lists brief descriptions of the major domains of cognitive functions and several representative tests that are commonly used in the literature described below.
Numerous health-related factors have been demonstrated to influence cognition (with effect sizes ranging from small to large). Examples include lifestyle, endocrine, and genetic factors, systemic diseases, neurotoxic exposures, and medical and surgical treatments for disease. Each of these general areas is considered briefly below, with positive findings emphasized for illustrative purposes.
A variety of lifestyle factors are known to affect cognitive function. Such factors may impact cognition by exerting direct biological influence on the brain or by promoting various systemic diseases (e.g., cardiovascular, pulmonary) that indirectly affect the brain. Less healthful lifestyles also tend to aggregate among individuals with lower levels of education and may, in part, explain previously noted associations between low education and/or socioeconomic status and poorer cognitive function (Kilander et al., 1997). Examples of such lifestyle factors include smoking, excessive alcohol consumption, illicit drug use, dietary factors, and physical inactivity.
With respect to health-compromising behaviors, several studies have revealed poorer cognitive performance among individuals who smoke tobacco products (M.F. Elias et al., in press; Galanis et al., 1997; Hill, 1989; Launer et al., 1996). Heavy alcohol consumption also has known deleterious effects on cognition (Rourke and Løberg, 1996; Tarter and Van Thiel, 1985). However, across a range of habitual drinking, several investigations have noted an in-