Hallucinations in visually impaired individuals: an analysis of the National Comorbidity Survey Replication.

OBJECTIVE

Charles Bonnet syndrome (CBS) is by complex visual hallucinations and ocular pathology causing vision loss. It has been considered that CBS occurs frequently in elderly visually handicapped patients and the hallucinations are limited to the visual modality. Three hypotheses we examined were: (1) whether visual impairments are associated with visual hallucinations (2) whether visual impairments are associated with auditory hallucinations (3) whether the development of visual and auditory hallucinations in patients with visual impairments is associated with age.

METHOD: Data from the National Comorbidity Survey Replication (NCS-R) in the United States were used to examine whether associations between visual impairments and visual hallucinations can be found in the general population, and whether such influences of visual impairments are limited to the visual modality and to specific age groups.

RESULTS

Prevalence of visual and auditory hallucinations in respondents with visual impairments were 12.8% (95% Confidence Interval (CI)=3.4-22.2%) and 7.1% (95%CI=2.6-11.6%) respectively. Although the point estimates were substantive, the odds ratios between visual impairments and existence of visual hallucinations or auditory hallucinations were not statistically significant (odds ratio (OR)=2.43, 95%CI=0.92-6.44, P=0.07 and OR=2.16, 95%CI=0.87-5.33, P=0.10, respectively) in the whole sample. Association between visual impairments and visual hallucination was significant (OR=3.09, 95%CI=1.06-8.99, P<0.05) only in the elderly (age group 60-), while significant association was found between visual impairments and auditory hallucinations in a younger age group (age group 18-39, OR=13.25, 95%CI=2.99-58.75, P<0.001).

CONCLUSION

Visual impairments act as a trigger for both visual and auditory hallucinations. In patients with visual impairments, the presence of visual hallucinations was associated with an age over 60, while the existence of auditory hallucinations was associated with an age under 39.