Perea-Bartolome et al. BMC Public Health 2011, 11:504 http://www.biomedcentral.com/1471-2458/11/504 development of dementia, but a drop in blood pressure can be observed in the phase prior to the development of diffuse cognitive impairment [28]. Likewise, no clear effect of antihypertensive treatment has been observed in terms of the prevention of mild cognitive impairment in hypertensive patients. A Cochrane review [31] concludes that “There was no con- vincing evidence in the reviewed trials to suggest that lowered blood pressure prevents the development of dementia or cognitive impairment in hypertensive patients without manifest prior cerebrovascular disease”. However, on considering the evidence of the cross-sec- tional, longitudinal and observational studies together with the evidence generated by the randomized clinical trials (RCTs), moderately solid support is found of the notion that hypertension in adult life - particularly when not treated effectively - exerts a negative effect upon cognition, and contributes to the development of dementia and Alzheimer’s disease in old age [17,19,32]. There is less evidence from these studies that the same negative effect upon cognition is present with hyperten- sion at an older stage in life [19]. The relationship between cholesterol and mild cogni- tive impairment is contradictory. There are several cross-sectional PAPPS studies with differing results [33,34]. There are also several longitudinal studies reporting a positive association between total choles- terol and mild cognitive impairment, while three observe no association, and one reports a negative association [35]. In reference to diabetes mellitus, a number of studies have reported an association with the prevalence of dementia, though others have found no such relation- ship. Biessesls et al. [36], following an analysis of several longitudinal studies, found the incidence of dementia to increase between 50-100% in subjects with diabetes ver- sus individuals without diabetes. Associations have also been described with blood glucose [37] and glycosylated hemoglobin. In this sense, for every 1% rise in HbA1c, an increased risk of cognitive impairment or dementia has been reported (OR 1.40: CI 1.08-1.83)[38]. Metabolic syndrome groups a series of cardiovascular risk factors; as a result, an increased risk of target organ damage could be expected in patients with this syn- drome. However, few studies have evaluated the associa- tion between metabolic syndrome and the development of dementia or mild cognitive impairment. Some cross- sectional [39] and longitudinal studies [40] have described an association between metabolic syndrome and cognitive impairment. Thus, while a certain rela- tionship appears to exist, the risk of dementia in indivi- duals with metabolic syndrome has not been firmly established, and it is not clear whether such risk is greater than the sum of its components [38]. Page 3 of 8 Comorbidity among people over age 65 is common and conditions the prognosis of other concomitant dis- ease processes, with an acceleration of the possible com- plications. Different methods are available for assessing comorbidity. Charlson proposed a numerical scale using a list of pathological conditions: the Charlson comorbid- ity index [41,42]. This index was designed to classify comorbidities for prognostic purposes, and posteriorly has been used as a control of the influence which comorbidity may exert in different situations. The Charlson index has not been used in the analysis of car- diovascular risk factors and cognitive impairment. Like- wise, no study has been made of the association of cardiovascular risk as estimated from the risk scales and cognitive impairment in individuals over 65 years of age. Less than one-half of all patients with Alzheimer’s dis- ease have been diagnosed, and of these subjects, approxi- mately 25% are receiving some kind of treatment [43]. The number of individuals with undiagnosed cognitive impair- ment is therefore expected to be high, particularly in groups with certain risk factors. One of the factors explaining why many people with cognitive impairment have not been diagnosed is related to the fact that we have no cognitive impairment screening tool in the elderly population sufficiently warranted by the scientific commu- nity and the professionals who care for such patients. Based on a neuropsychological battery especially adapted for the study of elderly people, we will carry out a study of cognitive performance in people over 65 years of age in Salamanca (Spain), with special emphasis on the identification of early symptoms of cognitive impairment, with the purpose of detecting mild cogni- tive impairment and of studying the relationships between this clinical situation and cardiovascular risk factors. The following objectives have been established: 1. To study the cognitive performance of people over 65 years of age in Salamanca, with a view to estimat- ing the prevalence of the different manifestations of cognitive impairment and its severity. 2. To analyze the association of cardiovascular risk factors (diabetes, arterial hypertension, dyslipidemia and metabolic syndrome) in patients over age 65 with mild cognitive impairment. 3. To use the Mini - Mental State Examination (MMSE) and the 7 Minute Screen test as screening tools for cognitive impairment in the elderly popula- tion under study. Methods/Design Design and study population A longitudinal study will be carried out, since we will be starting from a reference population of 327 people