Capgras delusions are typically focused on a small number of people or just one person. These people are typically emotionally close to the deluded person; atypically, Mr J believed that every person was a robot, even people he did not know very well, including doctors and nurses. Because of this particular clinical feature, we would define his psychopathological condition as Capgras-like syndrome. The clinical report presented here clearly suggests a correlation between an acute infection and delusional symptoms, and to our knowledge, this is the first case report of an association between urinary tract infection and Capgras-like syndrome.
Several psychopathological areas are usually impaired in Capgras syndrome and in this case impaired consciousness, thoughts, memory, perception, and allo psychic derealization were involved. We can argue that such a complex symptomatology could indicate diffuse functional damage of the brain. For this reason, it is possible to hypothesize that the frequent association between organic disease and misidentification delusions is linked to wider neuronal interconnectivity (hodological) problems rather than to specific topological problems.
Even if delusional misidentifications are known to be potentially correlated with infectious conditions, few relevant papers are available in the scientific literature. Crichton and Lewis reported on a patient with acquired immune deficiency syndrome who developed Capgras syndrome as part of an acute confusional state resulting from an opportunistic infection.20
In 1991, Förstl et al reviewed 260 case reports of misidentification syndromes,21
and identified two cases in association with pneumonia, one case in association with tuberculosis, one case in association with acquired immune deficiency syndrome, and one case in association with neurocysticercosis.
It is also true that several other infective conditions may exacerbate or lead to different kinds of acute psychosis. Infections caused by Epstein–Barr virus,22
human immunodeficiency virus,24Mycoplasma pneumoniae
and Salmonella typhi29
have been reported as possible causes of acute psychosis.
In cases of infective diseases with secondary sepsis, there may be two different pathological mechanisms related to brain injury. On the one hand, we could have an injury related to the inflammatory system, including proinflammatory cytokines, and in particular tumor necrosis factor alpha. This mediator could involve direct cellular damage to the brain, mitochondrial and endothelial dysfunction, and disturbances in neurotransmission.30
On the other hand, we may have a direct interaction between the proinflammatory system and cholinergic transmission that produces confusion directly.31
Environmental agents, such as stress or bacteria, are unlikely to be sufficient to induce a delusional syndrome; in the case of Mr J, a vulnerability to psychosis was identified in the family history, ie, his great-grandmother being affected by schizophrenia.
An interesting feature of this case is the theme of robots. To date, only one paper has reported robots or androids as possible misidentifications occurring in Capgras syndrome.9
This may be related to the fact that only in the last few years has the presence of robots with human features become culturally and internationally relevant (for example with the “Blade Runner” film and the books written by Isaac Asimov). It is possible that the contents of misidentification delusions are changing (humans become androids) concomitantly with general cultural issues of the day, and that other terms should probably be used to describe this emerging psychopathological syndrome, eg, “android syndrome”.
It is often difficult to distinguish between psychosis due to organic conditions and psychosis heralding the onset of a chronic psychotic illness, in particular when there is a positive family history of schizophrenia (as in the case of Mr J) and when different kind of medications are given concomitantly, like the antipsychotics and antibiotics in the present case.
In the future, it would be extremely valuable to perform functional magnetic resonance imaging to investigate delusional misidentification syndromes further. Awareness of the prevalence of delusional misidentification syndromes associated with acute medical illness should promote diligence on the part of clinicians in recognizing this disorder. Organic disease should be ruled out before a diagnosis of a mental or cognitive disorder is made.