Extended Abstract
1. Objectives
Elderly people are prone to cognitive impairment due to the gradual loss of their physiological and psychological capabilities [1]. These disorders not only lead to a significant decrease in their quality of life but also incur a significant economic burden on the health-care organizations and the families of the elderly [2]. Although no specific etiology has been identified for these disorders, some factors such as serum lipid levels have been reported as a potential and modifiable risk factor for cognitive impairment [3]. On the other hand, the ease of evaluation, low cost, and less aggressive methods of non-genetic biomarkers (such as the concentration of lipids and serum lipoproteins) have made these biomarkers important as a screening tool for neurological disorders [4, 5]. In this regard, this study aims to investigate the cognitive status of elderly people living in Amirkola City, Babol County, Iran and evaluate its relationship with their serum lipid levels and other underlying factors.
2. Methods & Materials
This cross-sectional study was conducted from September 2016 to March 2017 (6 months). The statistical population consisted of all elderlies living in Amirkola City. By considering inclusion and exclusion criteria, 1519 samples were selected based on the census method. The inclusion criterion was aged between 60 and 80 years, and the exclusion criteria were the unwillingness to continue the study, inability to answer the questions, returning incomplete questionnaires, having hypothyroidism, multiple sclerosis, drug abuse, use of other drugs that affect blood lipoproteins, and having incomplete medical records.
The study data were collected using a demographic form. Also, the Mini-Mental State Examination (MMSE) questionnaire was used for measuring the cognitive status of the subjects. MMSE is a 30-item tool that screens and assesses the severity of cognitive impairment in terms of awareness of time and place, registration, attention, calculation, recall, language, executive skills, reading, writing, and drawing [6]. AA100 AutoAnalyzer was used for measuring subjects’ serum lipids and blood glucose levels and the Friedewald formula was employed for calculating low-density lipoprotein level [7, 8].
The obtained data were analyzed in SPSS V. 22 by using descriptive statistics (frequency, percentage, mean, standard deviation) and inferential statistics (Kolmogorov-Smirnov, Chi-squared, and 1-way ANOVA). For evaluating study hypotheses and research questions, the Tukey post hoc test was used. The significance level was set at less than 0.05 (P<0.05).
3. Results
Most study participants were male (55.4%) with a Mean±SD age of 69.40±7.40 years. The Mean±SD MMSE score of the subjects was 25.3±3.93. According to the results, 30.6% of the subjects (n=465) had abnormal cognition (mild, moderate, and severe cognitive impairment) and in particular 13 (9%) had severe cognitive impairment. Based on the Chi-squared test results, there was a significant relationship between gender and cognitive impairment (P<0.05), but other underlying factors, including smoking, history of stroke, heart attacks, epilepsy and seizure, heart failure, diabetes, and hypertension had no significant association with cognitive impairment (P>0.05).
One-way ANOVA was used to compare the mean values of studied variables (age, blood pressure, blood sugar, cholesterol, triglycerides, and lipoprotein) between groups with different levels of cognitive impairments; the results are presented in Table 1. As seen, there is a significant difference between variables of age, systolic blood pressure, total cholesterol level, and low-density lipoprotein among subjects with different levels of cognitive impairment (P<0.05). The Tukey post hoc test results showed that variables of age (78.15±8.11 years), systolic blood pressure (148.62±24.24 mm Hg), total cholesterol level (207.46±48.05 mg/mL), and low-density lipoprotein (130.68±38.11 mg/mL) of elderlies with severe cognitive impairment (group 4) are significantly higher than those in the groups with normal, mild, and moderate cognitive impairments (groups 1 to 3).
4. Conclusion
Based on the study results, cognitive impairment in the elderly living in the study area is high. A significant relationship was found between cognitive impairment and old age, systolic blood pressure, total cholesterol level, and low-density lipoprotein, where the values of these factors in elderlies with severe cognitive impairment were higher than those values in groups with normal, mild, and moderate cognitive impairments. Considering the relatively high prevalence of cognitive impairment in this study, screening for cognitive impairments is one of the recommendations of this study because early diagnosis and treatment of this disease, especially in high-risk groups such as women and the elderly with hypertension and impaired serum lipid profiles, can play an important role in better controlling the disease and reducing the care burden of these patients. Moreover, due to the close relationship between depression and cognitive impairment, screening older people for depression can also be of great importance.

Ethical Considerations
Compliance with ethical guidelines
This research has been approved by Babol University of Medical Sciences. The research objectives and procedure were explained to the participants and they were assured of the confidentiality of their information. They were allowed to leave the study at any time.
Funding
This study was financially supported by Deputy of research and technology of Babol University of Medical Sciences (Grant code: 930280). 
Authors' contributions
Conceptualization and validation: Alijan Ahmadi Ahangar and Payam saadat; Methodology: Seyed Reza Hosseini and Ali Bijani; Formal analysis: Seyed Ehsan Samaei and Mostafa Mostafazadeh Bora; Investigation, resources, and draft preparation: AlijanAhmadiAhangar, Mandana Kalantar, Seyed Ehsan Samaei and Pyam Saadat; Editing: Payam Saadat; Visualization, supervision, and project administration: Alijan Ahmadi Ahangar; and funding acquisition: Alijan AhmadiAhangar.
Conflict of interest
The authors declared no conflict of interest.
Acknowledgments
The authors would like to express their gratitude to the Clinical Research and Development Unit of Ayatollah Rouhani Hospital, Babol City, Iran. The authors also thank all the elderly who participated in this study and the officials of the Master Plan of "Amirkola Aging and Health Project."