Diabetes Mellitus and microRNA as Risk Factors for Mild Cognitive Impairment: Impact of Life Style Modification

The current study was carried out during the period from February 2016 to June 2019 on two steps.

1. First step (baseline assessment): It was a cross sectional study carried out on 163 Type 2 Diabetes Mellitus (T2DM) patients attending outpatient clinics at NRC. Patients were 65 males and 98 females; aged from 40 to 65 years. All patients were literate and were able to complete the tests of cognitive function. The exclusion criteria were T2DM patients with history of head trauma, stroke, transient ischemic attack, brain tumor, epilepsy, psychiatric disease, cardiac or liver failure and visual or hearing disabilities. Approval of NRC ethical committee was obtained with registration number 15131. Participants signed a written informed consent before being included in the study.

1.1 A face to face interview was carried out with all participants to collect data about demographics, medical history and cognitive function. Data included age, gender, level of education, and tobacco smoking. Detailed medical history of diabetes was taken from patients including age of diagnosis of diabetes, frequency of hypoglycemic attacks, type of treatment (insulin or oral hypoglycemic drug), history of hypertension, dyslipidemia or other diseases and medications taken. Any complaint suggestive for presence of sensory peripheral neuropathy such as tingling, burning pain or numbness in hands and feet was recorded. All studied participants were subjected to thorough clinical examination, systolic and diastolic blood pressure and anthropometric assessment (weight and height measurements).

1.2 Assessment of cognitive function with its domains was carried out using Adenbrooke's Cognitive Examination III (ACE III) test which assesses five cognitive domains: attention, memory, verbal fluency, language and visuospatial abilities. It is the most reliable and validated Arabic form cognitive scale and freely available to be applied. Objective mild cognitive impairment (MCI) was considered if ACE III score is less than 88. The Trail Making Test (TMT) was also used. TMT is one of the most widely used instruments in neuropsychological assessment as an indicator of speed of cognitive processing and executive functioning. It assesses attention, concentration, psychomotor speed, cognitive shifting and complex sequencing function by measuring the time required to connect a series of sequentially numbered and lettered circles. The test consists of two parts (A and B). The direct score of each part is represented by the time of completion of the tasks. Shorter time indicates better cognitive function.

1.3 Hamilton Rating Scale for Depression (HRSD) was used, it is one of the most widely used scales that objectively rate depression severity. The scale includes 17 items, each one is scored on a 3 or 5 points scale, with the final score indicative of the severity of the patient's depression. The classification of depression level was carried out depending on the National Institute for Health & Clinical Excellence of the United Kingdom (UK) (0-7 = Normal, 8-13 = Mild depression, 14-18 = Moderate depression, 19-22 = Severe depression and ≥ 23 = Very severe depression).