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CHARLES BONNET SYNDROME, INSIGHT AND COGNITIVE IMPAIRMENT

1997; Wiley; Volume: 45; Issue: 7 Linguagem: Inglês

10.1111/j.1532-5415.1997.tb01524.x

1532-5415

Robert J. Teunisse,

Neurology and Historical Studies

To the Editor: In a recently published study, Pliskin et al.1 compared 15 patients with the Charles Bonnet syndrome (CBS) with 11 controls and found impairment of neuropsychological function to be associated with CBS. They propose that the Charles Bonnet Syndrome in the older adult may be an indication of the early stages of dementia. In describing their method, they state that the 15 CBS patients met the diagnostic criteria outlined by Gold and Rabins.2 However, in describing symptomatology, they mention that eight patients had no insight into the unreality of the hallucinations and three had delusions toward them. This means that, contrary to their earlier statement, more than half of their patients did not meet diagnostic criteria of Gold and Rabins.2 The editorial comment on this issue is that “one might argue that these individuals no longer meet the strict definition of CBS.”3 I think this point deserves more attention. Adequate reality testing is essential in the definition of Gold and Rabins. The criteria “retention of insight” and “absence of delusions” are of critical importance to discriminate CBS from true psychotic syndromes, including those in patients with dementia. Therefore, though the results of this study suggest that “visual hallucinations, in general,” may be the presenting symptoms of dementia, one should not draw conclusions regarding CBS. The diagnostic criterion “insight” is discussed in a recent paper on the characteristics of CBS in 60 individuals.4 CBS patients usually have a prompt and full insight into the unreality of their hallucinations. There are only a few understandable exceptions to this rule. First, the initial hallucinations can be bewildering and confusing experiences for some patients, and it may take a few hallucinatory episodes before they understand fully what is happening. Second, if hallucinations contain ordinary (“possible”) objects that fit realistically into the surroundings, it may be very difficult or even impossible to discriminate real from unreal. However, CBS patients, knowing they are “hallucination prone,” are easily and promptly corrected by others in such cases. Some experienced CBS patients, afraid to make embarrasing mistakes, even assume a sceptical attitude towards their visual perceptions in general. This may be illustrated by the account of one of my CBS patients, a retired university professor, who was hospitalized because of a broken hip: “Occasionally, when the nurse pushes me in my wheelchair through the hallway, I notice various persons standing in the way. I really can't tell whether they are real or hallucinations and so I keep silent and rely on the nurse to ask them to step aside in case they are real.” “And what happens if they are hallucinations?” I asked him. “Well, in that case she pushes me right through them,” he answered. It remains to be seen how many demented patients with visual hallucinations would meet CBS criteria: awareness of the fact that what one sees is not present in reality implies the fullfillment of a rather difficult cognitive task. As yet, there is no reliable evidence that true CBS patients are more at risk for dementia.