Background and Objectives: Alzheimer’s dementia is a progressive neurodegenerative disease that affects memory abilities due to genetic and environmental factors. A well-known gene that influences the risk of Alzheimer’s disease is the apolipoprotein E (APOE) gene. The APOE gene is involved in the production of a protein that helps transport cholesterol and other types of fat in the bloodstream. Problems in this process are thought to contribute to the development of Alzheimer’s disease. APOE comes in several forms, which are called alleles (ε2, ε3, ε4). Materials and Methods: Therefore, our study aims to identify those subjects with a higher genetic risk through the polymorphism of the APOE gene, using a population screening in patients with a clinical diagnosis of AD in a region of Spain, Castilla y León, as potential biomarkers and to identify individuals at increased genetic risk by polymorphism of the APOE gene. An observational case-control study was conducted in Castilla y León (Spain). Saliva samples were collected and the ApoE gene was analyzed by PCR and agarose gel electrophoresis, respecting ethical criteria. Results: In the Alzheimer’s population in Castilla y León, a high prevalence of ApoE3 (74%) was found, followed by ApoE4 (22%); in addition, a higher presence of the ε4 allele was found in the Alzheimer’s disease (AD) group than in the control group. It was also observed that the ε2/ε2 genotype was not found in any individual with AD but was found in healthy subjects and that the opposite was observed for the ε4/ε4 genotype. The odds ratio (OR) indicated a risk four times greater of having AD if having the ε4 allele. Conclusions: The demonstrated relation between the different isoforms and the likelihood of developing AD has led to its consideration as a biomarker and a potential pre-symptomatic therapy. The molecular mechanisms that confer a disruptive and protective role to ApoE4 and ApoE2, respectively, are still being studied.

Background: Parkinson’s Disease (PD) is the second most prevalent neurodegenerative disease worldwide. Motor and non-motor symptoms of PD cause functional disabilities. Aquatic-based therapeutic exercise (AT) is a potential approach that may improve the management of PD, given its hydrostatic and hydrodynamic properties. We aimed to evaluate the effectiveness and safety of AT compared to traditional land-based therapeutic exercise (LT) in patients with PD. Methods: Based on the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, we systematically reviewed studies indexed in PubMed, Scopus, Web of Science, PEDro, CINAHL, and Cochrane. Registered in PROSPERO (CRD42024528310), this review involved original studies published from 2014 to December 2024, with a randomized controlled trial (RCT) design, in which the intervention group performed AT, and the control group performed LT. The outcomes evaluated were balance, gait, quality of life, strength, mental health, pain, flexibility, and sleep quality. Results: Of the 413 records identified, 135 duplicates were removed, and 265 did not meet the selection criteria. Thirteen RCTs comprising 511 patients (age range: 50–80 years) were eligible. Most studies reported beneficial effects of AT, with no serious adverse events. Compared to LT, AT led to significant improvements (p < 0.05) in quality of life, mental health, pain, flexibility, and sleep quality. No evidence was provided of the beneficial effects of AT compared to LT on balance, gait, and strength; however, significant improvements were observed in the AT group from baseline (p < 0.05). Conclusions: AT appears to be a safe and effective intervention for improving the quality of life, mental health, pain, flexibility, and sleep quality in PD patients. While balance, gait, and strength may also benefit, the evidence comparing AT to LT remains inconclusive due to variability in study protocols.