Face processing in Alzheimer's disease - defining the deficit

人脸识别障碍是阿尔茨海默病(AD)中一种常见的、高度情绪化的早期症状。AD患者变得无法认出认识的人，包括亲戚和亲密的朋友，造成了很大的痛苦。识别熟悉的面孔的问题通常被归因于AD的标志性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，面部识别受损可能有不同的病因。Lavallee等人。(2016)要求AD患者同时匹配不熟悉的面孔，要么是直立的，要么是倒立的。使用倒脸的理由是基于倒脸效应，即对倒脸陌生面孔的识别障碍。AD患者表现出倒置效应的减少，反映出建立对个人面孔的连贯知觉表征的能力受损。这表明，面部处理能力受损可能不仅仅是由于以阿尔茨海默病为特征的标志性遗忘综合症，也可能是由于高级视觉处理能力受损。对基本机制的描述对干预和管理具有影响。首先，人脸处理对于大多数社交来说都是至关重要的。随着疾病负担的进展，AD患者的社会认知受到损害，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，一些患者可能在疾病过程的早期出现社交缺陷，这与面部加工受损有关。因此，识别AD患者面部识别受损的机制有助于识别那些更有可能发展为社会缺陷的患者。第二，确定与人脸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、量身定做的康复方案，以支持社会功能并更长时间地保持生活质量。本研究的目的是：(1)确定AD患者面孔识别缺陷的记忆与知觉基础；(2)研究面孔加工与社会认知之间的关系。参与者：健康老年人；从NHS和社区招募的阿尔茨海默病患者。方法：实验认知测试；神经心理学评估。

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.