The elderly woman saw people who would not respond to her, but she had no dementia or psychiatric conditions.
Mrs. T was an 87-year-old widow whose sons were worried that she might be suffering from hallucinations. Concerned, too, about their mother’s gradually increasing frailty, they had recently moved her to an apartment building for senior citizens. At our first meeting, she and the son who accompanied her reported that she had been having hallucinations for the past year or two. One prominent hallucination was of a face sitting on her sofa. In others, the patient saw people in her apartment or in the hallway who would not speak to her.
While Mrs. T’s sons were most worried about her hallucinations, they also thought their mother had begun to experience some memory loss. Recently she had forgotten her brother’s name but eventually recalled it. On separate occasions, she had forgotten to turn off the coffeepot and the oven. Each time she remembered before there were any problems. Otherwise, she was quite functional, being independent in activities of daily living, such as bathing, dressing, and eating. Her two sons managed her bank account and provided transportation.
PAST MEDICAL HISTORY
Mrs. T’s history was significant for prolonged hospitalizations and multiple surgeries on her left leg for osteomyelitis during childhood. As a result, her left leg was one inch shorter than her right. More recent operations included right hip replacement, left knee replacement, right carpal tunnel release, and cataract surgery in both eyes. In addition, she had been diagnosed with macular degeneration 10 years previously, but it was not clear whether she had ever received treatment. She complained that her vision had deteriorated in the past year or so.
The only medicines Mrs. T was taking were available without a prescription, including aspirin, calcium carbonate, a brand-name multivitamin, and a vitamin product recommended for patients with macular degeneration. In the recent past, she had taken hydrochlorothiazide for edema and hydroxyzine for pruritus that interfered with sleep, but she had not taken either medicine for months.
Her social history was significant for the loss of her husband in 1999. Although her formal education had ended at the 10th grade, she eventually received her high school equivalency certificate in the 1970s. She had never smoked, and her only alcohol consumption was limited to an occasional glass of wine with dinner.
Prior to retiring, she had been employed for 30 years as a payroll accountant for a large corporation. Her family history was notable only for remarkable longevity: Mrs. T’s mother died at the age of 101 from pneumonia and her father died at 96 of unknown causes. There was no family history of Alzheimer’s disease or other dementias or of psychiatric illnesses.
Mrs. T’s vital signs were normal. Testing with a Snellen chart revealed greatly reduced visual acuity. Even with corrective lenses, vision in her right eye was 20/160 and in her left was 20/100. On neurologic examination, she was alert and cooperative with testing. She scored 26 out of a possible 30 on the Folstein Mini-Mental State Examination, even without allowing for her visual impairment (for example, she was unable to copy a diagram of intersecting pentagons).
Further questioning showed that she was aware of the visual hallucinations, which were not accompanied by auditory hallucinations, and she did not fear them. She did not relate any delusions, that is, firmly held false beliefs despite evidence to the contrary. Her gait was slow and tentative, and she confessed to a fear of falling. The remainder of her exam and her lab results were unremarkable.
TRACKING DOWN A CAUSE
What was causing Mrs. T’s hallucinations? Her clear sensorium and long history effectively ruled out delirium, and she was taking no medicines with psychotropic effects. She had no personal or family history of psychosis, which generally makes its appearance in young adulthood. Indeed, she married and raised a family, was gainfully employed in a responsible position for 30 years, and had even gone back to school in late middle age to obtain her high school equivalency certificate.
Psychosis has been known to occur late in life but only rarely. In any event, Mrs. T had no delusions or evidence of bizarre behavior. She knew the people in her hallucinations weren’t real. She tested this by speaking to them and acknowledged that when they didn’t reply, they weren’t really there. While she wasn’t afraid of these visions, she did want to understand their cause and stop them if possible. The face on her sofa disappeared when her son removed a throw pillow.
Mrs. T was suffering from a common but underrecognized problem: Charles Bonnet syndrome. An 18th-century Swiss naturalist, Bonnet initially described this condition in his 89-year-old grandfather, who, blind from cataracts, nonetheless described visions of men and women. In this syndrome, partially sighted individuals have well-formed visual hallucinations due not to a psychiatric illness but rather to attempts by the visual cortex to make sense of poor or distorted input from their eyes.
Prevalence is thought to be as high as 10% or 15% in individuals with visual impairment. Diagnostic criteria are not universally defined, but typically, patients have vivid and well-formed hallucinations. These might be momentary or last throughout the day, but they have no personal significance. Unlike delirious or psychotic individuals, Bonnet syndrome patients realize that these visions are hallucinations.
HELPING MRS. T
Mrs. T’s visual impairment was due to long-standing but recently worsening macular degeneration. Other types of visual impairment present in Charles Bonnet syndrome include cataracts, as was the case in Bonnet’s grandfather, and glaucoma. Treatment varies with the cause of the visual impairment. When cataracts are the cause, surgery is often curative. Additionally, the reassurance of a diagnosis is helpful.
Mrs. T and her son were relieved to receive a diagnosis for this puzzling problem. Obviously, treatment with antipsychotic drugs, which might be indicated for a demented patient suffering from frightening hallucinations, was not indicated and had potential to do significant harm.
We referred Mrs. T to a specialist in macular degeneration. Even if it is not treatable, there is evidence that nonpharmacologic interventions, such as improved lighting or increased contact with others, can be helpful. She also accepted our referral for physical therapy to improve her stability and lessen the risks of falls.