Supplementary Material for: The role of brain integrity in the association between occupational complexity and cognitive performance in subjects with increased risk of dementia

Introduction: Mechanisms underlying the positive association between occupational mental demands and late-life cognition are poorly understood. The objective of this study was to assess whether the association between occupational complexity and cognition is related to and moderated by brain integrity in individuals at-risk for dementia. Brain integrity was appraised throughout structural measures (Magnetic Resonance Imaging, MRI) and amyloid accumulation (Pittsburgh Compound B (PiB)-positron emission tomography, PiB-PET). Methods: Participants from the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) neuroimaging sample -MRI (N=126), PiB-PET (N=41)- were included in a post-hoc cross-sectional analysis. Neuroimaging parameters comprised the Alzheimer´s Disease signature cortical thickness (ADS, Freesurfer 5.3), medial temporal atrophy (MTA), and amyloid accumulation (PiB-PET). Cognition was assessed using the Neuropsychological Test Battery. Occupational complexity with data, people, and substantive complexity were classified through the Dictionary of Occupational Titles. Linear regression models included cognition as dependent variable, occupational complexity, measures of brain integrity, and their interaction terms as predictors. Results: Occupational complexity with data and substantive complexity were associated with better cognition (overall cognition, executive function) when adjusting for ADS and MTA (independent association). Significant interaction effects between occupational complexity and brain integrity were also found, indicating that, for some indicators of brain integrity and cognition (e.g., overall cognition, processing speed), the positive association between occupational complexity and cognition occurred only among persons with higher brain integrity (moderated association). Conclusion: Among individuals at-risk for dementia, occupational complexity does not seem to contribute towards resilience against neuropathology. These exploratory findings require validation in larger populations.

引言：职业心理负荷与晚年认知功能之间的正相关关联机制目前尚不明晰。本研究旨在评估痴呆高危人群中，职业复杂度与认知功能的关联是否与大脑完整性相关，并受大脑完整性调节。大脑完整性通过两类指标进行评估：一是结构影像学指标磁共振成像（Magnetic Resonance Imaging, MRI），二是淀粉样蛋白沉积检测，采用匹茨堡化合物B正电子发射断层扫描（Pittsburgh Compound B (PiB)-positron emission tomography, PiB-PET）完成。

方法：本研究纳入芬兰老年认知障碍与残疾预防干预研究（Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability, FINGER）神经影像学子队列的参与者，包括磁共振成像亚组（N=126）与PiB-PET亚组（N=41），并对其开展事后横断面分析。本研究的神经影像学指标包括：阿尔茨海默病特征性皮层厚度（Alzheimer´s Disease signature cortical thickness, ADS，采用FreeSurfer 5.3软件分析）、内侧颞叶萎缩（medial temporal atrophy, MTA）以及淀粉样蛋白沉积情况（由PiB-PET评估）。认知功能采用神经心理测试组合（Neuropsychological Test Battery）进行评估。职业复杂度包含数据维度、人际维度与实质复杂度三个维度，通过《职业名称词典》（Dictionary of Occupational Titles）进行分级。本研究采用线性回归模型，以认知功能为因变量，以职业复杂度、大脑完整性指标及其交互项作为预测变量。

结果：在校正ADS与MTA后，数据维度职业复杂度与实质复杂度均与更优的认知功能（总体认知、执行功能）呈正相关，此为独立关联。本研究还发现职业复杂度与大脑完整性之间存在显著交互效应，提示在部分大脑完整性与认知功能指标（如总体认知、加工速度）中，职业复杂度与认知功能的正相关关系仅存在于大脑完整性较高的人群中，此为调节效应。

结论：在痴呆高危人群中，职业复杂度似乎并不能提升个体对抗神经病理损伤的韧性。本探索性研究结果需在更大规模人群中进行验证。