Hallucinations are very startling and frightening: you suddenly see, or hear or smell something — something that is not there. Your immediate, bewildered feeling is, what is going on? Where is this coming from? The hallucination is convincingly real, produced by the same neural pathways as actual perception, and yet no one else seems to see it. And then you are forced to the conclusion that something — something unprecedented — is happening in your own brain or mind. Are you going insane, getting dementia, having a stroke?
In other cultures, hallucinations have been regarded as gifts from the gods or the Muses, but in modern times they seem to carry an ominous significance in the public (and also the medical) mind, as portents of severe mental or neurological disorders. Having hallucinations is a fearful secret for many people — millions of people — never to be mentioned, hardly to be acknowledged to oneself, and yet far from uncommon. The vast majority are benign — and, indeed, in many circumstances, perfectly normal. Most of us have experienced them from time to time, during a feveror with the sensory monotony of a desert or empty road, or sometimes, seemingly, out of the blue.
Many of us, as we lie in bed with closed eyes, awaiting sleep, have so-called hypnagogic hallucinations — geometric patterns, or faces, sometimes landscapes. Such patterns or scenes may be almost too faint to notice, or they may be very elaborate, brilliantly colored and rapidly changing — people used to compare them to slide shows.
At the other end of sleep are hypnopompic hallucinations, seen with open eyes, upon first waking. These may be ordinary (an intensification of color perhaps, or someone calling your name) or terrifying (especially if combined with sleep paralysis) — a vast spider, a pterodactyl above the bed, poised to strike.
Hallucinations (of sight, sound, smell or other sensations) can be associated with migraine or seizures, with fever or delirium. In chronic disease hospitals, nursing homes, and I.C.U.’s, hallucinations are often a result of too many medications and interactions between them, compounded by illness, anxiety and unfamiliar surroundings.
But hallucinations can have a positive and comforting role, too — this is especially true with bereavement hallucinations, seeing the face or hearing the voice of one’s deceased spouse, siblings, parents or child — and may play an important part in the mourning process. Such bereavement hallucinations frequently occur in the first year or two of bereavement, when they are most “needed.”
Working in old-age homes for many years, I have been struck by how many elderly people with impaired hearing are prone to auditory and, even more commonly, musical hallucinations — involuntary music in their minds that seems so real that at first they may think it is a neighbor’s stereo.
People with impaired sight, similarly, may start to have strange, visual hallucinations, sometimes just of patterns but often more elaborate visions of complex scenes or ranks of people in exotic dress. Perhaps 20 percent of those losing their vision or hearing may have such hallucinations.
I was called in to see one patient, Rosalie, a blind lady in her 90s, when she started to have visual hallucinations; the staff psychiatrist was also summoned. Rosalie was concerned that she might be having a stroke or getting Alzheimer’s or reacting to some medication. But I was able to reassure her that nothing was amiss neurologically. I explained to her that if the visual parts of the brain are deprived of actual input, they are hungry for stimulation and may concoct images of their own. Rosalie was greatly relieved by this, and delighted to know that there was even a name for her condition: Charles Bonnet syndrome. “Tell the nurses,” she said, drawing herself up in her chair, “that I have Charles Bonnet syndrome!”
Rosalie asked me how many people had C.B.S., and I told her hundreds of thousands, perhaps, in the United States alone. I told her that many people were afraid to mention their hallucinations. I described a recent study of elderly blind patients in the Netherlands which found that only a quarter of people with C.B.S. mentioned it to their doctors — the others were too afraid or too ashamed. It is only when physicians gently inquire (often avoiding the word “hallucination”) that people feel free to admit seeing things that are not there — despite their blindness.
Rosalie was indignant at this, and said, “You must write about it — tell my story!” I do tell her story, at length, in my book on hallucinations, along with the stories of many others. Most of these people have been reluctant to admit to their hallucinations. Often, when they do, they are misdiagnosed or undiagnosed — told that it’s nothing, or that their condition has no explanation.
Misdiagnosis is especially common if people admit to “hearing voices.” In a famous 1973 study by the Stanford psychologist David Rosenhan, eight “pseudopatients” presented themselves at various hospitals across the country, saying that they “heard voices.” All behaved normally otherwise, but were nonetheless determined to be (and treated as) schizophrenic (apart from one, who was given the diagnosis of “manic-depressive psychosis”). In this and follow-up studies, Professor Rosenhan demonstrated convincingly that auditory hallucinations and schizophrenia were synonymous in the medical mind.
While many people with schizophrenia do hear voices at certain times in their lives, the inverse is not true: most people who hear voices (as much as 10 percent of the population) are not mentally ill. For them, hearing voices is a normal mode of experience.
My patients tell me about their hallucinations because I am open to hearing about them, because they know me and trust that I can usually run down the cause of their hallucinations. For the most part, these experiences are unthreatening and, once accommodated, even mildly diverting.
David Stewart, a Charles Bonnet syndrome patient with whom I corresponded, writes of his hallucinations as being “altogether friendly,” and imagines his eyes saying: “Sorry to have let you down. We recognize that blindness is no fun, so we’ve organized this small syndrome, a sort of coda to your sighted life. It’s not much, but it’s the best we can manage.”
Mr. Stewart has been able to take his hallucinations in good humor, since he knows they are not a sign of mental decline or madness. For too many patients, though, the shame, the secrecy, the stigma, persists.
By OLIVER SACKS
Published: November 3, 2012