APOE Genotypes Modulate the Relationship of Hypertension With Alzheimer's Disease: Associations and Clues of Peripheral Mechanisms.

Head and neck cancer (HNC) refers to a heterogeneous group of malignant tumors arising from the mucosal surfaces of the oral cavity, pharynx, larynx, nasal cavity, and paranasal sinuses. Radiation therapy, often in combination with chemotherapy, is the primary treatment modality for this condition. Due to the anatomical location and radiosensitivity of surrounding tissues, patients with head and neck cancer (HNC) are particularly prone to developing radiation-induced dermatitis (RID), an acute skin reaction to ionizing radiation. In this patient population, the incidence of RID approaches 100%, presenting a significant clinical challenge. The clinical manifestations associated with this condition range from mild erythema and pruritus to more severe reactions, such as dry or wet desquamation. Unlike dermatological side effects in other body regions that can be easily concealed by clothing, RID in patients with HNC occurs on the face and neck—areas that are highly visible and critical for social interaction and self-identity. This unique visibility makes concealment difficult, thereby exacerbating the patient's vulnerability to profound psychosocial consequences, including body image disturbance, psychological distress, and avoidance of social activities, ultimately impairing quality of life. In severe cases, RID may necessitate unanticipated interruption of radiotherapy, which could potentially compromise treatment efficacy. The physical changes associated with RID may be associated with reduced social functioning. Given the exposed nature of the symptoms, patients may experience feelings of shame or heightened self-consciousness, which may in turn be associated with social withdrawal and reduced social functioning. Social integration, defined as the extent to which an individual participates in social networks and maintains a sense of connectedness and belonging to their community, is a crucial component of psychosocial well-being and recovery. A body of research, particularly among survivors of breast cancer, has identified a correlation between treatment-related appearance changes and social avoidance, depression, and diminished self-esteem. This finding indicates that the relationship between physical symptoms and social outcomes is not direct, but rather is likely influenced by underlying psychological processes. Guided by the Biopsychosocial Model, we hypothesize that physical symptoms (RID) do not occur in isolation but elicit psychological responses (mood states) that are, in turn, associated with behavioral outcomes (social integration). Investigating these interrelationships is essential to identify whether psychological support can mitigate social impairment even when physical symptoms persist. Mood states, encompassing negative emotions (e.g., tension, depression, fatigue) and positive emotions (e.g., vitality, self-esteem), appear to be an important factor. This distinction is grounded in the Two-Factor Theory of Affect, which posits that positive and negative emotions are distinct dimensions that can coexist and independently influence psychological functioning. Furthermore, grouping subscales into these two broad dimensions allows for a parsimonious examination of whether social impairment is associated with the presence of distress, the absence of vitality, or both. This distinction is potentially relevant for future intervention research, as the Broaden-and-Build Theory suggests that positive and negative emotions may benefit from different strategies. Previous research has identified mediators such as body image disturbance and stigma. However, these studies predominantly focus on negative psychological outcomes. Mood state represents a more immediate and proximal psychological reaction to physical symptoms than complex cognitive constructs like stigma. Furthermore, focusing solely on distress overlooks the potential role of positive psychological resources (e.g., vigor), which are critical for social engagement. Therefore, this study selects mood states to capture both the accumulation of negative affect and the depletion of positive affect as dual pathways. The present study is primarily guided by the Theory of Unpleasant Symptoms (TOUS). This theoretical framework posits that symptom experience comprises three interrelated components: the symptom itself, influencing factors, and functional outcomes. Within the proposed model, RID is conceptualized as the primary symptom, and social integration is operationalized as the functional outcome. While TOUS traditionally categorizes psychological variables as influencing factors that moderate outcomes, recent adaptations of the model in cancer research suggest that psychological responses can also act as proximal mediators. Based on the TOUS framework and the theoretical distinctions described above, the following hypotheses were specified prior to data collection to guide the planned mediation analysis: mood state functions as a proximal psycho