Face processing in Alzheimer's disease - defining the deficit

面部识别受损是阿尔茨海默病（AD）的一个经常报道的、高度情绪化的早期症状。阿尔茨海默病患者会变得无法认出认识的人，包括亲戚和亲密的朋友，这给他们带来了很大的痛苦。识别熟悉面孔的问题通常被归因于阿尔茨海默症标志性的情景记忆缺陷和巩固记忆的退化。然而，最近的一项研究表明，受损的面部识别可能有不同的病因。Lavallee等人（2016）要求AD患者匹配同时呈现的不熟悉的面孔，无论是直立还是颠倒呈现。使用倒立人脸的理由是基于人脸倒立效应，即对倒立陌生人脸的识别受损。阿尔茨海默氏症患者表现出倒置效应减弱，反映出对个体面孔建立连贯知觉表征的能力受损。这表明受损的面部处理可能不仅仅是由于阿尔茨海默氏症的标志性失忆综合征，也可能是由于受损的高级视觉处理。对潜在机制的描述对干预和管理具有启示意义。首先，人脸处理对大多数社会互动至关重要。随着疾病负担的加重，阿尔茨海默病患者的社会认知受损，这反过来又与患者预后较差和照顾者更大的痛苦有关。然而，越来越多的文献表明，一些患者可能在发病早期出现社交缺陷，这与面部处理受损有关。因此，确定AD患者面部识别受损的机制有助于识别那些更有可能出现社交缺陷的患者。其次，确定与面部识别相关的记忆和感知过程将有助于为AD患者设计基于证据的量身定制的康复方案，以支持社会功能并保持更长时间的生活质量。本研究旨在：(1)确定AD患者面部识别缺陷的记忆与知觉基础；(2)研究人脸加工与社会认知的关系。参与者：健康的老年人；从NHS和社区招募阿尔茨海默病患者。方法：实验认知测试；神经心理评估。

Impaired face recognition is a frequently reported, highly emotive early symptom in Alzheimer's disease (AD). AD patients become unable to recognise known people, including relative and close friends, causing much distress. Problems with recognising familiar faces have typically been attributed to the hallmark episodic memory deficit in AD and the degradation of consolidated memories. However, a more recent study has suggested impaired face recognition may have a different etiology. Lavallee et al. (2016) asked AD patients to match simultaneously presented unfamiliar faces, presented either upright or reversed. The rational for using inverted faces was based on the face-inversion effect, i.e. impairment in recognising inverted unfamiliar faces. AD patients showed a reduced inversion effect reflecting an impaired ability to build a coherent perceptual representation of individual faces. This suggests that impaired facial processing may not be solely due to the hallmark amnesic syndrome that characterises AD, but may also be due to impaired higher-level visual processing. The delineation of the underlying mechanism has implications for intervention and management. Firstly, processing of human faces is critical for most social interaction. Social cognition is impaired in AD patients with progression of disease burden, which in turn is linked to poorer outcomes for patients and greater caregiver distress. However, an increasing body of literature suggests that some patients may develop social deficits earlier in the disease process, with links to impaired face processing. Identifying the mechanisms that underpin impaired face recognition in AD could therefore help to identify those patients more likely to develop social deficits.Secondly, determining the memory vs perceptual processes linked to face recognition will help to devise evidence-based, tailored rehabilitation protocols for AD patients to support social functioning and maintain quality of life for longer. This study aims to: (1) determine memory vs. perceptual underpinnings of face recognition deficits in AD;(2) examine the relationship between face processing and social cognition.Participants: Healthy older adults; patients with Alzheimer's disease recruited from the NHS and community.Methodologies: Experimental cognitive testing; neuropsychological assessment.