Visual Hallucinations and HLA Class II Antigens in Cortical Dementia

Background: Visual hallucinations are a core feature of dementia with Lewy bodies (DLB) and have been proposed as being part of a narcolepsy-like REM sleep disorder. Selective loss of hypothalamic hypocretin-producing neurons is common to both narcolepsy and the spectrum of Lewy body diseases. We hypothesized that the genetic marker associated with narcolepsy, the HLA class II DR2-DQ6 haplotype, could confer some degree of susceptibility to brainstem-hypothalamic damage leading to the manifestation of visual hallucinations. Methods: We examined HLA class II haplotypes in 30 patients with prominent visual hallucinations in the context of clinical criteria for DLB and in 30 patients affected by a cortical-type dementia without hallucinations. Results: No significant differences were found in the distribution of DR and DQ antigens. Conclusions: We conclude that hypothalamic vulnerability in different diseases is not mediated by a common HLA haplotype.