Prosopagnosia is the inability to recognize someone by the face alone, in the absence of sensory or intellectual impairment (Schwarzer et al., 2006). Almost all reported cases are of the acquired form, but there is evidence for a ... Prosopagnosia is the inability to recognize someone by the face alone, in the absence of sensory or intellectual impairment (Schwarzer et al., 2006). Almost all reported cases are of the acquired form, but there is evidence for a familial form as well (McConachie, 1976; de Haan, 1999; Galaburda and Duchaine, 2003; Kennerknecht et al., 2006).
McConachie (1976) described a 12-year-old girl who had never been able to recognize any but the most familiar faces. Examination and testing revealed some evidence of right hemisphere abnormality on EEG, some directional confusion and disturbance of topographic ... McConachie (1976) described a 12-year-old girl who had never been able to recognize any but the most familiar faces. Examination and testing revealed some evidence of right hemisphere abnormality on EEG, some directional confusion and disturbance of topographic memory, and difficulty with complex visual discrimination and integration. Her mother also reported difficulty with recognizing familiar faces, raising the possibility of familial transmission. McConachie (1976) noted that because so-called 'developmental prosopagnosia,' in which there is no history of brain injury, can be circumvented by various strategies, it might be more common than is generally believed. De Haan and Campbell (1991) reexamined the patient originally described by McConachie (1976) and administered an extensive series of tests of face recognition ability and related functions, comparing her performance to that of 4 women of comparable educational background and age. The patient's basic visuosensory functions, such as acuity, contrast sensitivity, and color perception, were largely intact; and general face perception, e.g., distinguishing between a face and a 'nonface,' was relatively well preserved. Recognition of familiar faces was severely impaired, and she also showed problems with other face-processing tasks, such as analysis of facial expression, and with object recognition. This apparent functional impairment was supported by subsequent studies, which demonstrated a complete absence of covert face recognition. De Haan (1999) studied a family in which several members had difficulty with face recognition to such a degree that the mother would instruct them beforehand about who was coming to visit, and the father once introduced himself to his own daughter when they met in an unusual setting. Upon examination, the father and 2 daughters tested very poorly on a familiar face recognition task, whereas the mother and a brother had no face recognition deficit. Another sister, who reportedly had no difficulty with face recognition, declined to participate in the study. Galaburda and Duchaine (2003) reported a 4-generation family with prosopagnosia, including father-to-son transmission. The proband was a 42-year-old man who recalled incidents early in childhood when he could not recognize close family members, and he had failed to recognize nearly all his relatives at times. It was not until he entered the army that he realized the severity of his problem, when the uniform appearance of his fellow servicemen left him unable to differentiate between people. He also reported that he frequently mistook strangers for acquaintances. His son, mother, and grandmother also had prosopagnosia. Schwarzer et al. (2006), commenting on their clinical experience with 38 hereditary prosopagnosics, stated that all of the patients reported that throughout their entire life they had been unable to recognize people by their faces alone, sometimes not even recognizing very close relatives, and used context and other attributes such as voice and hair to identify individuals. Schwarzer et al. (2006) noted that the perception of facial details is not grossly distorted in these patients, all of whom can perceive normal attractiveness and emotions and can identify gender. In a detailed study of the gaze behavior of 8 hereditary prosopagnosics compared to 4 gender- and age-matched controls, Schwarzer et al. (2006) found that while the control participants focused their gaze on the central facial features in face recognition tasks, the hereditary prosopagnosics had a more dispersed gaze and also fixated on external facial features. The difference in gaze pattern was independent of recognition performance, i.e., even when the prosopagnosics recognized a face correctly, compared to the control participants their gaze was significantly more dispersed. Schwarzer et al. (2006) concluded that the face recognition impairment of hereditary prosopagnosics is reflected in their gaze behavior. Kennerknecht et al. (2007) reported an Indian woman with hereditary prosopagnosia. She described identifying people by hair cuts, glasses, teeth, clothing, and sometimes by smile. She had normal recognition of attractiveness but had difficulty with inner imaging of her parents, close friends, and some objects. Neurologic exam showed no other abnormalities. She was socially well-integrated and was a university student of high caliber. Family history revealed a total of 8 other affected members from both the maternal and paternal sides of the family. Her mother, but not her father, was affected. Kennerknecht et al. (2007) suggested that the occurrence in both sides of the family was consistent with a high prevalence of the disorder. Kennerknecht et al. (2008) reported detailed clinical features of 10 unrelated Chinese medical students with prosopagnosia. All prosopagnosic students had pronounced difficulties in the recognition of close relatives and had often been reproached for not greeting them. All reported the use of compensatory strategies and behavioral adaptation, such as reliance on multiple extrafacial cues including gesture, spectacles, gait, hairstyle, perfume, clothing, and jewelry, or arriving early at social meetings to avoid having to locate people. They also had difficulties in recognizing key actors or actresses in movies or television and had to rely on their friends to navigate them through the stories.
From a survey conducted in 3 local high schools and 1 university in Germany, Kennerknecht et al. (2006) analyzed 689 completed questionnaires and identified 65 individuals who were 'highly suspicious' for congenital prosopagnosia. After in-depth interviews of 43 ... From a survey conducted in 3 local high schools and 1 university in Germany, Kennerknecht et al. (2006) analyzed 689 completed questionnaires and identified 65 individuals who were 'highly suspicious' for congenital prosopagnosia. After in-depth interviews of 43 individuals, the diagnosis was established in 17 persons (6 males and 11 females), yielding a prevalence of 2.47% in the German Caucasian population. Of those 17 cases, 14 allowed interviewing of at least 1 first-degree relative, and all had at least 1 affected first-degree relative. Kennerknecht et al. (2006) concluded that congenital prosopagnosia is a very common cognitive disorder that is almost always familial, and suggested that the long-term use of compensatory strategies prevents many affected individuals from realizing that they have a specific dysfunction. Using a questionnaire-based screening method, Kennerknecht et al. (2007) identified 1 female Bengali student with prosopagnosia among a total of 189 native Indian university students. Using a questionnaire of 533 Chinese Han medical students followed by personal interviews in a selected subgroup, Kennerknecht et al. (2008) identified 10 (1.88%) individuals with prosopagnosia, including 4 with a family history of prosopagnosia consistent with autosomal dominant inheritance. In an accompanying commentary, Duchaine (2008) suggested that there may be a difference between heritable forms of the disorder and nonheritable forms. He reported that only 11 (58%) of 19 prosopagnosic individuals in his own study clearly had affected relatives. Duchaine (2008) further suggested that the 6 affected individuals reported by Kennerknecht et al. (2008) who did not have a family history of the disorder may not have had a heritable form, thus reducing the frequency to 0.75%. However, even this reduced frequency would still represent a 'staggering number of Han Chinese with hereditary face recognition problems,' about 9.75 million.