Source: wikipedia.org

“Voices inside my head, echo the things that you said.”

—The Police, “Voices Inside My Head"

Auditory –loosely defined as hearing something when there’s no actual noise to hear–are one of the more stereotypical and recognizable symptoms of those who have psychotic disorders like . Among those with mental illness, the most common form of this particular symptom is the experience of hearing people talking, known colloquially as “voice-hearing” or, more technically, as auditory verbal hallucinations (AVH).

Despite the fact that AVH are a prototypical example of a psychotic symptom, it has long been debated whether voice-hearing should always be equated with the presence of a psychotic disorder. I tackled this issue a few years ago with the publication of a paper called “Hallucinations in Non-psychotic Disorders: Towards a Differential Diagnosis of “Hearing Voices” [1]. In it, I highlighted how voice-hearing is known to occur in people without psychotic disorders as well as people without mental illness. It is well known, for example, that many historical luminaries were voice-hearers, including Socrates and Plato, Joan of Arc, Sigmund and , and Martin Luther King, Jr. to name a few. In the paper’s conclusion, I suggested that:

“Similar to the likening of to fever, auditory hallucinations might be best compared to coughs–normal and even functional experiences that can occur spontaneously or in response to environmental stimulation, reflect or be part of a larger clinical disorder, or be malingered [feigned]. As with coughs, clinicians and researchers ought to focus on recognizing what makes AH clinically relevant, distressing, or functionally impairing. Depending on these factors, potential treatment strategies might include watchful waiting, palliative therapies directed at the “symptom” itself, or targeting the larger, underlying disease.”

A study published earlier this year, based on a World Health Organization (WHO) survey of over 30,000 people across 18 countries, revealed that 2.5% of respondents reported voice-hearing at some point in their lives [2]. I was subsequently interviewed by U.S. News & Report about this paper, with the reporter expressing surprise that voice-hearing was such a common experience. In fact, the reported prevalence of 2 to 3 voice-hearers out of every 100 people is low compared to other similar studies that have found rates of anywhere from less than 1% to 84% [3].

Why such widely varying rates? For one thing, it appears that the detection of voice-hearing depends on who’s being asked, how they’re being asked, and who’s doing the asking. For example, the highest prevalence of voice-hearing was found in a small study of just 55 mental health nurses in the U.K. who filled out a written questionnaire about hearing a voice “as if someone had spoken aloud rather than a thought or feeling” [4]. This questionnaire included such experiences as hearing one’s name called “like in a store when you walk past some people… but know they didn’t really say my name,” “hearing the doorbell or phone ring when it didn’t” (without any actual voice-hearing), and hearing a voice while falling asleep or awakening (hypnopompic and hypnagogic hallucinations, which are not unusual in those with sleep disturbances). When considering those commonplace experiences along with the use of an anonymous pencil-and-paper questionnaire to elicit them (which might result in a greater willingness to divulge experiences suggestive of mental illness), the study’s 84% response rate is not so surprising. In contrast, the lowest reported voice-hearing prevalence of only 0.6% was found in a study using a telephone interview administered in the U.K., Germany, and Italy that specifically excluded the hypnopompic and hypnagogic hallucinations experienced by nearly everyone in the study at some point in their lives [5].

In the recent WHO study, interviews of all 30,000+ subjects were conducted in person using the question, “Have you ever heard voices that other people said did not exist?” Positive responses while “ or half-asleep or under the influence of drugs” or from anyone with a psychotic disorder or were not included in the 2.5% positive response rate.

Now that we have a better understanding of the apparent commonality of voice-hearing, how do we make sense of these experiences? The prevailing approach in psychology now is to conceptualize voice-hearing that is part of mental illness and voice-hearing that isn’t as existing on a continuum. In other words, they’re fundamentally the same experience – hallucinations – but they differ somehow in terms of severity. More specifically, studies that have compared voice-hearing among “clinical” (help-seeking patients receiving professional treatment) and non-clinical persons reveal that voice-hearers who seek help tend to have voices that are perceived with greater frequency, more negative content, more associated distress, longer duration, less control, and greater associated interference with their lives and well-being [6]. As expected then, voice-hearers who don’t seek help tend to experience voices with more pleasant or neutral content that are more controllable and cause less distress or life interference.

Recently, researchers have turned to neuroimaging to explore how voice-hearing might differ between clinical and non-clinical individuals in terms of brain function. For example, investigators in the Netherlands used functional magnetic resonance imaging (fMRI) to explore how areas of brain activation during voice-hearing might differ between these two groups [7]. Rather than detecting differences, they found that “normal” or “non-psychotic” voice-hearing appears to involve the same areas of brain activation as “pathological” or “psychotic” voice-hearing. This supports the continuum model of hallucinations, or what I call the “lumping hypothesis,” that invites the comparison of hallucinations to coughs. Sometimes coughs are normal, if potentially annoying experiences that serve a purpose, while at other times they’re serious symptoms of a life-threatening condition. Maybe that’s the case with AVH.

And yet, I think it’s premature to discard the opposing “splitting hypothesis”, which argues that voice-hearing in clinical populations might be fundamentally different from that of non-clinical voice-hearers. Perhaps, for example, when “normal” people report voice-hearing, they aren’t really talking about AVH at all. This hypothesis best explains the wide range in rates of voice-hearing in epidemiologic surveys. For example, the U.K. investigators that found the 84% rate of hallucinations among mental health nurses conceded that the high rate might have reflected a conflation of actual and metaphorical expression [4].

These days in psychiatry, we rarely talk about one’s “ ,” though the concept is almost ubiquitous in pop-psychology and layspeech (see for example, Robert Firestone and Psychology Today Blogger Lisa Firestone's 2002 book, Conquer Your Critical Inner Voice). Most of us routinely think using language, even mentally addressing ourselves “in our heads” using both first and second person (e. . saying to oneself, “I’m going to be late” or “you’re going to be late”). Often this kind of self-talk can take on a critical tone (e.g., “I’m ugly,” “You’re going to be single forever,” “You’re never going to find ”) and sometimes we even seem to argue with ourselves in a kind of internal dialogue (e.g. “I want that piece of cake, but I know I shouldn’t… because you’re too fat!”). My favorite TV character when I was growing up, Magnum P.I., often talked about his “little voice” that reflected intuitions and hunches that emerged in his detective work – was Magnum a non-clinical hallucinator? I think we would all agree that the answer is no; that he was experiencing something altogether different than actually hearing a voice, as in a seemingly acoustic experience, which has been central to the definition of an AVH.

Sometimes though, patients and clinicians confuse things while attempting to find a common language to communicate. As a clinician, it can be tricky to distinguish auditory hallucinations from other frequently reported experiences that might be described similarly, such as our “inner voices” and internal thoughts. Among people who are clinically depressed, critical self-talk can often become unwanted, repetitive, and intrusive (in psychiatry, we call these “depressive ruminations”). Sometimes this might even create the impression, if not the actual belief or experience, that the thoughts aren’t quite one's own (psychiatrists call this “ego-dystonic”). Although people might use the word “voice” to describe these experiences, or might respond positively when asked by a clinician about “hearing voices,” these are not what psychiatrists mean when we ask about “hearing a voice when no one is around.”

Instead, when AVH occur as a part of mental illness, they typically take the form of distinctly hearing someone else’s voice rather than one’s own. One psychological theory currently in vogue suggests that AVH represent our own inner speech that is, for pathological reasons, experienced as coming from outside of ourselves. I’ve never been fond of this theory as an over-arching explanation of voice-hearing however. For one thing, patients with schizophrenia who have AVH still have intact inner speech that they experience as their own thoughts [8]. Also, regardless of diagnosis, voice-hearers don’t just experiences voices as external sound (as opposed to internal thoughts), they often clearly recognize the voice as someone else, attributing it to a family member or a known person from their past. For example, among victims of , it’s not unusual to hear the voices of one’s assailant. Because of such experiences, other theories have suggested that AVH might represent memories. My feeling is that is that there are probably many different experiences, in terms of what causes them, how they are subjectively experienced, and what’s going on inside the brain, that all fall under the broad umbrella of voice-hearing. It may therefore be necessary to consider multiple models to explain each of these experiences and perhaps one day we will come to view only a subset of these experiences as AVH [9,10].

As noted, voice-hearing in clinical and non-clinical persons appears to involve similar areas of brain activation, but there is other evidence from neuroimaging studies to support the splitting hypothesis. For instance, differences in brain activation during inner speech, self-criticism, intrusive thoughts, auditory imagery, and AVH suggest that these are all distinct experiences [11,12,13]. Furthermore, when comparing clinical and non-clinical voice-hearers, there appear to be differences in many other areas of the brain that might affect how voices are experienced, potentially contributing to differences in salience (how much people pay to their voices), localization (where the voice seems to be coming from), or character (what the voice sounds like) [13].

So, is it normal to hear voices? To a certain extent, it can be, but it’s also possible that when people talk about voice-hearing, they’re talking about a wide variety of different experiences. A more important question might be what it means to hear voices. While some people clearly report that voice-hearing can be a meaningful and even positive experience, many do not. Almost by definition, those seeking professional help for voice-hearing would prefer to do without the experience. A careful clinical evaluation first involves taking care to separate AVH from other non-psychotic experiences that might respond to distinct types of treatment, whether or other medications besides [14]. Second, since people with mental illness don’t usually just report voice-hearing alone (there is no such thing as “hallucination disorder”), a thorough examination would also carefully explore for other symptoms, such as thinking or evidence of or , that might lead to a clinician to a clearer diagnosis that would guide appropriate treatment.

In a previous blogpost, I argued against a “non-medical” approach to psychosis advocated by some and recently supported by the British Psychological Society (BPS), so I won’t repeat that debate here. However, it’s worth reviewing what medical research tells us about the clinical significance of psychotic symptoms like voice-hearing that makes psychiatrists concerned. For example, “subclinical psychotic experiences” like voice-hearing that aren’t associated with distress or help-seeking do appear to increase the risk of later developing a mental disorder, whether psychotic or otherwise [15,16]. A study just published this year found that psychotic symptoms such as AVH also increase the risk of premature death [17]. Still, an increased risk is not the same as a certainty and some people who report no distress from voice-hearing do just fine without professional help. But for those that do seek or otherwise end up under professional care, voice-hearing warrants a careful clinical evaluation and discussion of available treatment options that might relieve their burden.

Dr. Joe Pierre and Psych Unseen can be followed on Twitter at https://twitter.com/psychunseen. To check out some of my fiction, click here to read the short story "Thermidor," published in Westwind earlier this year.

References

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