Neuropsychological tests
All the neuropsychological assessments were performed prior to ADT and at the third and sixth months of ADT. Four neuropsychological tests, including the Symbol Digit Modalities Test (SDMT) [10], the California Verbal Learning Test, second edition (CVLT-II) [11]; the Brief Visuospatial Memory Test - Revised (BVMT-R) [11]; and the Trail Making Test (TMT) [12,13]were performed to cover 4 main cognitive areas. Depressive symptoms were measured using the Beck Depression Inventory (BDI) [14]. All the neuropsychological tests were completed in approximately 15–20 min in the supervision of trained physicians.
Attention and speed of processing : A written version of the SDMT was used to assess visual spatial scanning, attention and concentration, and information processing speed. Patients were asked to match as many symbols with digits 1–9 as possible in 90 s. The SDMT takes approximately 5 min to complete. The test result represents the number of correct answers [10].
Verbal memory : The CVLT-II is the standard scale of verbal learning and memory in clinical neuropsychology and has been widely used in clinical trials. The CVLT-II is composed of a 16-item word list. The examiner reads out the list of words to the participant in the same order. After each reading, the patient repeats as many words as possible in any order. The learning score represents the total number of correct words remembered in the first 5 attempts [11].
Visuospatial learning and memory : BVMT-R is a measurement tool of visuospatial learning and memory; it consists of 3 recall attempts. At the learning attempts, patients were asked to view 6 geometric figures for 10 s. Then they were asked to draw as many symbols as they can remember, in the correct position on an empty page. These drawn symbols are scored from 0 to 2, depending on accuracy and location, for a maximum of 12 points for each attempt to recall and draw the 6 figures. The highest possible score is 36 total for 3 recall attempts [11].
Executive functions: Executive functions comprise working memory, complex attention, problem solving, and response inhibition. The TMT evaluates visual search, attention, and executive function and is divided into 2 parts. The first part of the test evaluates speed and psychomotor attention and requires consecutively connecting randomly-distributed, encircled numbers from 1 to 25 [12]. The second part requires the subject to connect numbers and letters in alternating, ascending order [13]. Patients were asked to finish the test as quickly as possible, and the test time was recorded. A standardization study of this test in Turkish adults over the age of 50 was conducted by Cangöz et al [15].
Depressive symptoms : The BDI is used to assess depressive symptoms. In this scale, patients were asked to mark the most accurate expressions describing how they felt in the week leading up to and including the day of the test. The BDI test consists of 21 questions, with the following possible responses: not at all (0); mild (1); moderate (2), and severe (3). According to the scoring system, a 0–10 score is considered normal, 11–16 is mild mood disturbance, 17–20 is borderline mood, 21–30 is moderate depression, 31–40 is severe depression, and ≥41 is extreme depression [14].