Charles Bonnet syndrome: an early marker for dementia?

OBJECTIVE

To clarify the neuropsychological function in patients with Charles Bonnet Syndrome.

DESIGN

Control group comparison study.

SETTING

University of Chicago Hospitals.

PARTICIPANTS

The neuropsychological function of 15 older adults with presenting complaints of visual hallucinations who met criteria for Charles Bonnet Syndrome (CBS) were compared with 11 demographically matched controls to determine if there was any evidence of functional brain impairment. CBS patients were screened for focal brain lesions and epileptic disturbance via MRI and EEG and also received pattern visual evoked potentials and ophthalmological examinations.

MEASUREMENTS: Scores from the Wechsler Adult Intelligence Scale-Revised, Mattis Dementia Rating Scale, Wechsler Memory Scale, and the Auditory Verbal Learning Test were compared.

RESULTS

Significant differences were found between the two groups on the neuropsychological measures. Moreover, 14 of 14 subjects had ocular abnormalities and six of eight had abnormal age-corrected pattern visual evoked potentials indicative of dysfunction in the visual system.

CONCLUSIONS

The results of the study indicate that patients diagnosed with Charles Bonnet Syndrome evidence neuropsychological changes commonly associated with the early stages of dementia. Therefore, in patients with impaired vision, the appearance of cognitive deficits, albeit subtle, occur with the onset of visual hallucinations. We propose that isolated visual hallucinations in the older adult may be an indication of the early stages of dementia.