Extended Abstract
1. Objectives
arkinson Disease (PD) is a progressive neurological disease that causes motor dysfunction and cognitive decline and consequently creates many problems for the affected patients and their caregivers [1-3]. The prevalence of PD increases dramatically after age 60 [2]. Aging is one of the biggest risk factors for the development of PD, such that its prevalence in people aged 45-55 years is 0.02% and is estimated to reach 85.77% by the age of 85 [4]. On the other hand, some disorders and illnesses such as sleep disorder and impaired blood pressure can make a person more prone to cognitive impairments [5-8]. Regarding the effect of cognitive impairment on several factors, including health indicators, this study attempted to evaluate the relationship between visual and verbal memory impairment with health indicators of the elderly with PD.
2. Methods & Materials
This cross-sectional study was conducted on 30 older adults with PD living in Tehran (diagnosed by a neurologist) in 2017. They were selected based on convenience sampling method and the inclusion criteria were being 60-70 years old, having PD for 1-6 years, being able to read and write, being able to establish verbal communication and follow instructions, and lacking aphasia and linguistic problems. The exclusion criteria were the unwillingness to participate and returning incomplete questionnaires. After obtaining written informed consent from the participants, the data collection process was started. At first, the Montreal cognitive assessment tool was used to screen for cognitive impairment. 
Because of the high prevalence of visual and verbal memory impairment among PD patients, Wechsler memory scale was used to determine the verbal memory impairment, and Rey 15-item visual memory test was used to check the visual memory impairment. Moreover, to measure sleep quality of the subjects, the Pittsburgh sleep quality index was employed. The existence of blood pressure disorder in subjects was determined based on their medical records and specialist’s diagnosis. After collecting the study data, they were analyzed in SPSS V. 22.
3. Results
Of 30 participants, 15 were male and 15 females with a Mean±SD age of 64.76±7.87 years. More than 50% had high blood pressure and over 60% had sleep disorders. More than 96% of them had a visual impairment and 70% had verbal memory.  Based on the results of the Shapiro-Wilk test, all study variables had a normal distribution (P>0.05).
Based on a study, the prevalence of high blood pressure in Iranian people (Birjand City dwellers) was reported 20% [9]. In this study, it was more than 50%. This indicates a higher incidence of high blood pressure in the elderly with PD compared to the normal elderly population. In this regard, and considering the nature of PD in causing a disturbance between the acetylcholine and dopaminergic systems which leads to the dysfunction of acetylcholine system, imbalance of sympathetic nervous system and blood pressure [10], it can be said that high blood pressure can be a factor in exacerbating cognitive deficits.
According to the participants’ reports and based on PSQI results, symptoms such as tremor during sleep, activation of sympathetic nervous system, frequent urination, and sleep disturbances were the main causes of poor sleep quality which can affect the function of the brain and the information relay between the hippocampus and the cortex, and subsequently cognitive defects [11].
In order to examine the relationship between visual and verbal memory impairment with blood pressure and sleep disorders, the Pearson correlation test was used whose results are shown in Table 1. Based on the results, visual (P=0.031) and verbal (P=0.004) memory impairment had a significant correlation with high blood pressure (P<0.005). Between visual memory impairment and sleep disorder, there was also a significant correlation (P=0.045), but verbal memory impairment had no significant association with sleep disorder (P>0.05).
4. Conclusion
There is a significant relationship between memory impairment and health indicators of older people with PD. Therefore, it can be expected that by examining these factors and controlling them with timely medical interventions, the incidence and severity of cognitive impairment in these individuals can be manipulated and decreased. In order to better assess the memory status of the elderly people with PD, it is suggested that their narrative memory impairment with declarative memory impairment be compared using a larger sample size. Regarding the relationship between sleep disorder and memory impairment in people with PD, the sleep quality improvement techniques should be taught to them by proper rehabilitation and using physical interventions. Moreover, it is recommended that serious professional rehabilitation principles be reconsidered in occupational and social activities after 2 years.

 

Ethical Considerations
Compliance with ethical guidelines
This paper has been approved by University of Social Welfare and Rehabilitation  sciences IR.USWR.REC.1396.105. The research goals and process were explained to the participants and they were assured of the confidentiality of their information. They were free to quit the study at any time.
Funding
This paper was extracted from the MSc. thesis of Motahare Hejazi in Department of Occupational Therapy, University of Social Welfare and Rehabilitation Sciences. This research  received  specific grant from Clinical Research Development Center of Rofeideh Rehabilitation Hospital.
Authors' contributions
Conceptualization: Seyede Motahare Hejazi, Nazila Akbarfahimi, Hojjat Allah Haghgoo, Ashraf Karbalaei Nouri;  Methodology: Seyede Motahare Hejazi; Foramal analysis: Akbar Biglarian, Nazila Akbarfahimi; Writing review: Nazila Akbarfahimi, Hojjat Allah Haghgoo, Seyede Motahare Hejazi; and Final Editing: Nazila Akbarfahimi, Hojjat Allah Haghgoo. 
Conflict of interest
The authors declared no conflict of interest.
Acknowledgments
Authors are grateful to all the elderly people participating in this study, their care givers, the Chancellor and the staff of the Rofeideh rehabilitation hospital who helped authors to do this study.