Wednesday, March 21, 2007

BPS RESEARCH DIGEST: Brain damage turns man into human chameleon

BPS RESEARCH DIGEST: Brain damage turns man into human chameleon

Brain damage turns man into human chameleon

In his 1983 fake documentary 'Zelig', Woody Alan plays a character, Leonard Zelig, a kind of human chameleon who takes on the appearance and behaviour of whoever he is with. Now psychologists in Italy have reported the real-life case of AD, a 65-year-old whose identity appears dependent on the environment he is in. He started behaving this way after cardiac arrest caused damage to the fronto-temporal region of his brain.

When with doctors, AD assumes the role of a doctor; when with psychologists he says he is a psychologist; at the solicitors he claims to be a solicitor. AD doesn't just make these claims, he actually plays the roles and provides plausible stories for how he came to be in these roles.

To investigate further, Giovannina Conchiglia and colleagues used actors to contrive different scenarios. At a bar, an actor asked AD for a cocktail, prompting him to immediately fulfil the role of bar-tender, claiming that he was on a two-week trial hoping to gain a permanent position. Taken to the hospital kitchen for 40 minutes, AD quickly assumed the role of head chef, and claimed responsibility for preparing special menus for diabetic patients. He maintains these roles until the situation changes. However, he didn't adopt the role of laundry worker at the hospital laundry, perhaps because it was too far out of keeping with his real-life career as a politician.

AD's condition is a form of disinhibition, but it appears distinct from other well-known disinhibition syndromes such as utilisation behaviour, in which patients can't help themselves from using any objects or food in the vicinity. For example, AD didn't touch anything in the hospital kitchen.

His tendency to switch roles is exacerbated by anterograde amnesia (a loss of memory for events since his cardiac arrest) and anosognosia – a lack of insight into his strange behaviour.

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