MANY elderly patients with poor vision may be hiding the fact that they hallucinate from time to time for fear of being considered insane by their doctors, according to a study in The Lancet.
The phenomenon by which psychologically normal people with poor vision experience complex visual hallucinations was first described by Charles Bonnet, a Swiss philosopher, in 1760.
Bonnet's Syndrome usually affects older people and is thought to be triggered by poor vision and sensory deprivation. When Dutch researchers interviewed 505 visually handicapped people aged 18 years old and older, 63 admitted to having hallucinations which ranged in frequency from twice a year to twice a day.
Of the 61 who agreed to be psychologically assessed, 60 were psychologically normal. Only 16 of the 60 had ever dared consult a doctor about their hallucinations, and of these only one had received a proper diagnosis of Bonnet's Syndrome.