ABSTRACT
In the literature about visual hallucinations in Alzheimer's disease (AD) one can find a frequency of occurrence of 40%, with a range of 13–73%. These high estimates and range are problematic for clinical practice and care-giving, in that they suggest that hallucinations are frequent occurrences in AD and, implicitly, that they ‘should’ be present and found by clinicians. Reports that visual hallucinations are an even more frequent feature of Lewy body dementia (LBD) than AD have undoubtedly influenced the ‘probable’ diagnosis of both illnesses, but what exactly are visual hallucinations (in view of the new understanding of pathology to the visual system in AD) and the resultant perceptual deficits? How many types of ‘visual phenomena’ are there in AD? Are they sometimes mislabelled? Does such mislabelling have consequences for the care of persons with AD?
