Breast cancer is one of the most common cancer types worldwide and accounts for approximately 31% of all cancers in women. The global incidence of breast cancer is increasing, making it a significant public health problem. Advances in breast cancer management, including surgery, chemotherapy, radiotherapy, and hormone therapy, have contributed to reduced mortality rates. However, despite these positive developments, chemotherapy-related cognitive impairment, commonly referred to as "chemobrain," may occur. Chemotherapy-induced cognitive impairment may manifest as deficits in memory, learning, attention, motor functions, executive functions, visual-spatial abilities, and information processing speed. These impairments negatively affect patients' quality of life and daily functioning. In this study, cognitive education activities were designed and implemented to address these impairments. These activities aimed to support attention, memory, and executive functions and to minimize cognitive deficits. The purpose of this study was to examine the effects of cognitive activities applied to breast cancer patients receiving chemotherapy on cognitive functions, depression levels, and odor recognition abilities. The study sought to answer the following research questions: 1. What is the effect of cognitive education activities on odor recognition ability in breast cancer patients receiving chemotherapy? 2. What is the effect of cognitive education activities on cognitive functions in breast cancer patients receiving chemotherapy? 3. What is the effect of cognitive education activities on depression levels in these patients?
This randomized controlled trial was conducted between March 2025 and February 2026 at the oncology outpatient clinic and chemotherapy unit of Gulhane Training and Research Hospital. The study aimed to evaluate the effects of cognitive education activities on cognitive function, depression levels, and odor recognition ability in breast cancer patients receiving chemotherapy. A total of 120 patients who met the inclusion criteria were enrolled in the study. Eligible participants were between 18 and 65 years of age, literate, diagnosed with breast cancer, had received at least one cycle of chemotherapy, were continuing treatment, and had no diagnosed neurological or cognitive disorder before or during chemotherapy. In addition, participants had a Standardized Mini-Mental Test (SMMT) score of 24 or below. Participants were randomly assigned to intervention (n=60) and control (n=60) groups using a computer-generated randomization method. During the study, 12 participants withdrew for various reasons, and the study was completed with 108 participants (54 in each group). The study was designed as a single-blind, pre-test/post-test randomized controlled trial. The intervention group received structured cognitive education through printed booklets, face-to-face sessions, and weekly telephone counseling. The cognitive activity program was designed to stimulate attention, memory, executive functions, and language skills. Four cognitive activity booklets with progressively increasing difficulty levels were developed. Since chemotherapy sessions were scheduled every three weeks according to the hospital protocol, each booklet was structured to be completed over a three-week period. Face-to-face sessions were conducted every three weeks, resulting in a total of five sessions over a 12-week period. During these sessions, participants completed structured cognitive activities included in the activity booklets, such as sudoku, puzzles, sentence completion, pattern recognition, word derivation, coloring, and reading comprehension exercises, all of which were designed to support cognitive functions. Weekly telephone follow-ups were conducted to enhance adherence to the intervention. To assess olfactory function, odor identification tasks were performed using non-transparent containers. Familiar scents such as lavender, coffee, lemon, orange, onion, rose water, and cinnamon were used. The control group received routine care without any cognitive intervention during the study period. After completion of the study, the control group was also provided with cognitive activity training and the educational materials used in the intervention. Data were collected using a sociodemographic data form, an odor identification test, the Standardized Mini-Mental Test (SMMT), the Functional Assessment of Cancer Therapy - Cognitive Function (FACT-Cog) scale (Version 3), and the Beck Depression Inventory (BDI). Measurements were conducted at baseline and at 12 weeks following the initial assessment.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
SINGLE
Enrollment
108
Participants received structured cognitive training through printed activity booklets designed to support attention, memory, executive functions, and language skills. The booklets included activities such as puzzles, word derivation, sentence completion, pattern recognition, coloring, reading comprehension, and sudoku. Four booklets with progressively increasing difficulty levels were provided over a 12-week period. Each booklet was designed to be completed over three weeks. The intervention was supported by face-to-face sessions and weekly telephone follow-ups to enhance adherence.
Health Sciences University Gulhane Training and Research Hospital
Ankara, Etlik, Turkey (Türkiye)
Change in Cognitive Function (Standardized Mini-Mental Test)
Cognitive function was assessed using the Standardized Mini-Mental State Examination (SMMSE/SMMT). The scale evaluates global cognitive status across domains including orientation, registration, attention and calculation, recall, and language. Scores range from 0 to 30, where 30 represents maximum cognitive function and scores below 24 may indicate cognitive impairment. Higher scores indicate better cognitive performance.
Time frame: From baseline to the end of the 12-week intervention period
Change in Subjective Cognitive Function (Functional Assessment of Cancer Therapy - Cognitive Function)
Subjective cognitive function was assessed using the Functional Assessment of Cancer Therapy - Cognitive Function (FACT-Cog) Version 3. This self-report scale consists of 37 items categorised into four subscales: Perceived Cognitive Impairment, Comments from Others, Perceived Cognitive Abilities, and Impact of Cognitive Impairment on Quality of Life. Each item is rated on a 5-point Likert scale (0=Not at all to 4=Very much), with higher total scores indicating better perceived cognitive health and fewer cognitive complaints.
Time frame: From baseline to the end of the 12-week intervention period
Change in Depression Level (Beck Depression Inventory)
Depression levels were assessed using the Beck Depression Inventory (BDI), a 21-item self-report scale evaluating the severity of depressive symptoms. Total scores range from 0 to 63, with higher scores indicating more severe depressive symptoms.
Time frame: From baseline to the end of the 12-week intervention period
Odor Recognition Ability
Odor recognition ability was assessed using a structured odor identification test consisting of 8 common odors presented in opaque (non-transparent) containers. Participants were asked to smell each container and indicate whether they could correctly recognize the odor. The assessment was based on whether each odor was correctly identified or not, rather than a numerical scoring system. The odors included familiar scents such as coffee, lavender, lemon, orange, onion, rose water, cinnamon, and mint.
Time frame: From baseline to the end of the 12-week intervention period
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