Auditory, Visual Hallucinations Often Partner in DLB

Batya Swift Yasgur, MA, LSW

May 24, 2018

Patients with dementia with Lewy bodies (DLB), especially women and those with hearing impairments, frequently experience auditory hallucinations, new research suggests.

Investigators assessed 124 patients with DLB at a Japanese university hospital and found that while only a third had auditory hallucinations, most patients with auditory hallucinations also had visual hallucinations.

The auditory hallucinations were more likely to occur in women, as well as those with impaired hearing, depression, or delusions.

"I think clinicians should recognize the importance of auditory hallucinations when managing patients with DLB," lead author Naoko Tsunoda, MD, PhD,director at the Mitsugumachi Dementia Clinic, Kumamoto, Japan, told Medscape Medical News.

"Auditory hallucinations frequently occur and might be associated with other neuropsychiatric symptoms, such as delusions and depression," she said.

The study was published online May 8 in the Journal of Clinical Psychiatry.

Auditory Hallucinations Understudied

Neuropsychiatric symptoms, including hallucinations and delusions, are "core clinical features" of DLB, note the investigators.

Although auditory hallucinations are considered to be important features for the diagnosis of DLB, less attention has been paid to them than to visual hallucinations, and less is known about them, they write.

"In my clinical practice, I have seen no small [number of] DLB patients with auditory hallucinations, and those with auditory hallucinations seemed to be more difficult to treat than those without," Tsunoda said.

"But little has been known about the clinical features of auditory hallucinations in DLB," leading her to decide to study this topic.

The researchers assessed 124 patients with probable DLB (57% women; mean age at first examination, 78.3 years).

The patients were consecutively selected from those attending the dementia referral center at Kumamoto University Hospital between June 2007 and January 2015.

Participants completed the Mini-Mental State Examination (MMSE) and the Neuropsychiatric Inventory (NPI), and underwent MRI or CT and single-photon emission CT for cerebral perfusion.

The mean educational attainment of participants was 10.5 years, and the mean MMSE score was 19.1. The researchers used the Consortium on DLB International Workshop 2005 criteria for probable DLB in their inclusion criteria.

When auditory hallucinations were identified, patients were questioned regarding details of their hallucinations.

Age, Sex, and Impaired Hearing

Most of the patients (63.7%) reported having experienced hallucinations within the previous months. Of these, the largest percentage (60.5%) reported visual hallucinations, followed by 35.5% who reported auditory hallucinations and 32.3% who reported both auditory and visual hallucinations.

Almost all of the patients with auditory hallucinations also had visual hallucinations (90.9%), whereas only four patients reported auditory hallucinations unaccompanied by visual hallucinations.

There was a significant association with age: Those with auditory hallucinations were significantly older than those without (mean age, 79.8 vs 77.5 years, respectively; P = .02).

Additionally, there were significantly more women and significantly higher proportions of patients with hearing impairments among those with auditory hallucinations vs those without (70.5% vs 48.8% [P = .02] and 22.7% vs 6.3% [P = .007], respectively).

More patients with than without auditory hallucinations were taking antipsychotic medication (29.5% vs 12.5%, respectively; P  = .02).

Compared with patients in the non–auditory hallucinations group, those in the auditory hallucinations group had significantly higher total NPI scores (P  < .001), total NPI scores excluding the hallucinations domain (P  = .005), and total NPI scores excluding the hallucinations and delusions domain (P  = .02).

The two groups did not significantly differ with regard to educational attainment, MMSE scores, and the frequency of other drug use.

When the researchers conducted multiple logistic regression analysis, they found that the presence of auditory hallucinations remained significantly associated with being female (P  = .04), the presence of hearing impairment (P  = .004), and the use of antipsychotics (P  = .01).

Movie Soundtrack

Analysis of the contents of auditory hallucinations revealed that most consisted of human voices (in 41 patients), the sound of running water (1 patient), and unspecified sounds (2 patients).

The authors note that of the 41 patients with verbal auditory hallucinations, 37 patients (90%) heard the visual hallucinations speak.

Over half of the patients (61%) heard the visual hallucinations speaking specifically to them, with most (71%) reporting "bad" or "unpleasant" voices. Only 4 patients (10%) reported hearing "good" or "pleasant" voices.

Of the NPI individual domains, three were associated with the presence of auditory hallucinations: higher frequencies of delusions, depression, and aberrant motor behavior.

Delusions of persecution, delusions of theft, phantom boarder delusions, and the TV phenomenon were significantly more frequent in the auditory hallucination group than in the non–auditory hallucination group.

Multiple regression analysis showed that visual hallucinations (P  < .001), phantom boarder delusions (P  = .001), and depression (P  = .038) were independently correlated with the presence of auditory hallucinations.

"I was surprised that 36% of the patients with DLB had auditory hallucinations, and among these, over 90% also had visual hallucinations," said Tsunoda.

"Auditory hallucinations consisted mostly of human voices, and about 90% of patients described them as being similar to hearing a movie dialogue soundtrack," she added.

Hallucination vs Hearing Impairment

Commenting for Medscape Medical News, Ronald C. Hamdy, MD, professor of medicine and Cecile Cox Quillen chair of excellence in geriatric medicine, East Tennessee State University, Johnson City, called the study a "very, very nice review of auditory hallucinations, not only in DLB but otherwise as well."

"We knew all along that visual hallucinations are common in patients with DLB and, in fact, are one of the core features of DLB. But the new and positive things this study added are the focus on and descriptions of visual and auditory hallucinations," said Hamdy, who was not involved with the research.

The investigators "differentiate nicely between hallucinations and memory distortions, hearing impairments, or antipsychotic use," which is important because "before prescribing anything or even making diagnosis, it is important to make sure a patient is actually hallucinating and not experiencing a hearing impairment," he added.

He noted that in patients with impaired hearing, "any noise may be misinterpreted. For example, people may hear voices talking outside when it's raining at night."

When patients have tinnitus or other auditory impairments, "the cerebral cortex is trying to make sense of what it's hearing, and so a patient may think someone is talking or people are laughing, which can seem like a hallucination, but in reality is a compensatory mechanism," Hamdy explained.

The study therefore "encourages clinicians to make a differential diagnosis and try to identify nonpsychiatric causes of hallucinations," he emphasized.

The researchers concur that "auditory hallucinations might occur as a functional compensation for sensory impairment" and suggest that "improving the hearing ability could be a potential treatment option for auditory hallucinations in patients with DLB."

The study was funded by grants from the Ministry of Health, Labour and Welfare, Tokyo, Japan, and by the Ministry of Education, Culture, Sports, Science and Technology in Tokyo. The study authors and Hamdy have disclosed no relevant financial relationships.

J Clin Psychiatry. Published online May 8, 2018. Article

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