Malingering must clearly also be differentiated from factitious presentations associated with personality disorders [25–30]. One of the differential parameters is the time the simulation has lasted: usually, factitial behaviour without external incentives is chronic and persistent (for various reasons such as previous failures to diagnose the disorder, the fact that many physicians and hospitals have been con­sulted, refusal to accept the diagnosis and psychiatric treatment), whereas malinger­ing is episodic, opportunistic, and short-lasting. However, this parameter may not be valid in cases of a rst episode of factitious behaviour due to psychological or psy­chiatric disorders. Another differential parameter is the evidence of “external rewards” although even this parameter is questionable, both empirically and con­ceptually. Conceptually, the “absence” of external rewards cannot be equated with the “presence” of a strong internal motivation: the external rewards may sometimes be so banal that they do not seem important; moreover, the external rewards may be overshadowed by strong internal motivations [25]. On this point, other authors also believe that the presence of obvious external gain should not alone disqualify a diagnosis of a factitious disorder: a male patient, for example, could be engaging in deceptive behaviour, with exaggerated pain, for both external rewards (e.g. to obtain a narcotic to feed an addiction) and internal needs (e.g. to avoid chronic conicts with the partner) [31]. In both cases, the diagnosis must be based on very challeng­ing clinical and human constructs.