Multimorbidity, the presence of two or more health conditions, has been identified as a possible risk factor for clinical dementia. It is unclear whether this is due to worsening brain health and underlying neuropathology, or other factors. In some cases, conditions may reflect the same disease process as dementia (e.g. Parkinson's disease, vascular disease), in others, conditions may reflect a prodromal stage of dementia (e.g. depression, anxiety and psychosis).

To assess whether multimorbidity in later life was associated with more severe dementia-related neuropathology at autopsy.

We examined ante-mortem and autopsy data from 767 brain tissue donors from the UK, identifying physical multimorbidity in later life and specific brain-related conditions. We assessed associations between these purported risk factors and dementia-related neuropathological changes at autopsy (Alzheimer's-disease related neuropathology, Lewy body pathology, cerebrovascular disease and limbic-predominant age-related TDP-43 encephalopathy) with logistic models.

Physical multimorbidity was not associated with greater dementia-related neuropathological changes. In the presence of physical multimorbidity, clinical dementia was less likely to be associated with Alzheimer's disease pathology. Conversely, conditions which may be clinical or prodromal manifestations of dementia-related neuropathology (Parkinson's disease, cerebrovascular disease, depression and other psychiatric conditions) were associated with dementia and neuropathological changes.

Physical multimorbidity alone is not associated with greater dementia-related neuropathological change; inappropriate inclusion of brain-related conditions in multimorbidity measures and misdiagnosis of neurodegenerative dementia may better explain increased rates of clinical dementia in multimorbidity

多重发病，即存在两种或多种健康状况，已被确定为临床痴呆的可能危险因素。目前尚不清楚这是否是由于大脑健康状况恶化和潜在的神经病理学或其他因素造成的。在某些情况下，病症可能反映与痴呆症相同的疾病过程（例如帕金森病、血管疾病），而在其他情况下，病症可能反映痴呆症的前驱阶段（例如抑郁症、焦虑症和精神病）。

评估尸检时晚年的多重发病是否与更严重的痴呆相关神经病理学相关。

我们检查了来自英国的 767 名脑组织捐献者的生前和尸检数据，确定了晚年身体的多重疾病以及特定的大脑相关疾病。我们通过逻辑模型评估了这些所谓的危险因素与尸检时痴呆相关神经病理学变化（阿尔茨海默病相关神经病理学、路易体病理学、脑血管疾病和边缘系统年龄相关 TDP-43 脑病）之间的关联。

身体多重病与更大的痴呆相关神经病理学变化无关。在存在身体多重病态的情况下，临床痴呆与阿尔茨海默病病理学相关的可能性较小。相反，可能是痴呆相关神经病理学临床或前驱表现的病症（帕金森病、脑血管疾病、抑郁症和其他精神疾病）与痴呆和神经病理学变化相关。

单独的身体多重病与更大的痴呆相关神经病理学变化无关；在多发病测量中不恰当地纳入大脑相关疾病以及神经退行性痴呆的误诊可能更好地解释多发病中临床痴呆发生率的增加