The Cognitive Changes Among Patients over 65 Years of Age in a Rural Area—The Preliminary Report of Protective and Predisposing Factors

<b>Background:</b> Aβ1-42 and APOE concentrations, as well as Aβ42/40 ratio, may be considered as a link between hypertension (HTN) or diabetes mellitus (DM), brain amyloidosis, and dementia. HTN and DM are associated with cognitive impairment and may contribute to the development of Alzheimer's disease (AD). This preliminary study aimed to evaluate the impact of vascular risk factors on the concentration of biochemical AD markers and cognitive state. As it is a cross-sectional study in nature, causal relationships cannot be established. <b>Methods:</b> The study was conducted in the south of Poland among a rural population over 65 years of age. A total of 58 patients qualified into the study were divided into groups according to the presence of HTN (<i>n</i> = 18) or HTN coexisting with DM (<i>n</i> = 40). A healthy control group was also formed (<i>n</i> = 20), resulting in 78 study participants. The study population was also divided based on M-ACE results, forming a normal cognition group (NC) and a deteriorated cognition group (DC). Biochemical tests, neurological scales assessments, and ultrasound examinations were conducted. <b>Results:</b> Patients who scored in the normal range on the M-ACE had higher Aβ1-42 (median 38.52 vs. 27.35 pg/mL, <i>p</i> = 0.02) and apoE concentrations (median 125.0 vs. 65.73 μg/mL, <i>p</i> = 0.002), and a higher Aβ42/40 ratio (median 0.39 vs. 0.29 <i>p</i> < 0.000) compared to the DC group. Considering the study groups, the highest Aβ42/40 ratio was found among the HC group (median 0.47). The median score for the M-ACE scale was 3 points lower when HTN and DM coexisted, compared to the sole diagnosis of HTN (25 points and 28 points, respectively). A higher number of years of education correlated with better M-ACE results. Lipid and uric acid concentrations were not related to M-ACE or MMSE scores. An inverse relationship connected Aβ1-40 and Aβ1-42 to BMI, the duration of HTN treatment, and glycated hemoglobin. <b>Conclusions:</b> Aβ1-42, APOE, and Aβ42/40 are not only correlated with cognition but also related to patient's disease profile. The coexistence of DM and HTN was associated with the most significant decline in cognitive functioning. However, a higher number of years of education may protect against the development of dementia in old age. The roles of cholesterol and uric acid in cognitive decline are still inconclusive.