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Understanding Auditory Hallucinations: Beyond Schizophrenia

auditory-hallucinations

When we hear about people hearing voices, we often assume they are suffering with Schizophrenia or another psychiatric condition, however, studies show that auditory hallucinations are quite common in general populations (10%- 15% of the general population1), especially amongst children and adholescents2, meaning they can occur without other psychotic symptoms and may be caused by a range of conditions.

There are two types of auditory hallucination:

  • Verbal (hearing voices) in the absence of any speaker
  • Hearing sounds or noises

In the psychiatric population, these tend to be frequent, intrusive, and distressing. In contrast, in the nonclinical population, these are often predominantly positive and nonthreatening3. 

Conditions That Cause Auditory Hallucinations

Social Isolation and Withdrawal

It has been speculated that the psychological effects of loneliness and social seclusion may prompt compensatory hypersensitivity of the perceptual network4, with any hallucinations being projected outwards to meet the person’s communicative needs5. This means they might start seeing or hearing things that aren’t really there because their mind is trying to fill the gap and create a sense of connection with others.

Psychological Underpinnings of Auditory Hallucinations

Trauma

The neurocognitive Aberrant Memory Model6 explains auditory hallucinations as resulting from abnormal memory activation and monitoring, especially from past traumatic experiences. This happens because the brain fails to properly inhibit these memories, causing them to surface unintentionally. Waters et al. suggest that this is due to dysfunctional prefrontal inhibition.

The prefrontal cortex is a part of the brain involved in complex behaviours, decision making, and moderating social behaviour. Inhibition refers to the brain’s ability to control or suppress certain thoughts and actions. When we talk about “dysfunctional prefrontal inhibition,” it means that this part of the brain isn’t working properly to control or regulate thoughts and behaviours.

Crucially, when these uninhibited memories arise out of context, they feel unfamiliar and seem to come from an external source, leading to the sensation of “otherness” and the perception that the voices are from someone else.

When someone has experienced trauma, they might develop a symptom called hypervigilance. This means they are always on high alert, constantly looking out for danger. This heightened state of awareness, along with how they interpret different situations, can make them more likely to experience auditory hallucinations.

Anxiety plays a big role in this too. When someone is anxious, they are more likely to misinterpret unclear or vague signals as real threats. This lowered threshold means the person is more likely to accept ambiguous signals as real. Everyday examples include mothers believing their babies to be crying, and physicians on duty hearing the phantom ring of their pagers7. 

Borderline Personality Disorder

Studies show that those diagnosed with Borderline Personality Disorder (BPD) experience auditory hallucinations more than more frequently than previously assumed8 and in a similar way those diagnosed with schizophrenia9 10, including the perceived location of them, but they differ in frequency of paranoid delusions11 12, possibly because BPD and schizophrenia frequently coexist.

One study revealed that BPD patients experienced Auditory and Visual Hallucinations (AVH) for a mean duration of 18 years, with a mean frequency of at least daily lasting several minutes or more. Other studies highlight the risk of wrongly treating BPD patients as though they are suffering from schizophrenia9 10.

It is significant to note that studies have found that levels of reported childhood trauma are especially high in those with a BPD diagnosis9 11, as well as dissociative experiences9. For instance, clinical experience and increasing research suggest that AVH in BPD are often dissociative in origin and highly correlated with the presence of First Rank Symptom (of Schizophrenia), elevated levels of dissociation and a history of childhood trauma.

Dissociative Identity Disorder

The similarities in AVH between those diagnosed with Schizophrenia and those diagnosed with BPD that include histories of Trauma and Dissociative sysmptoms could be why those suffering with Dissociative Identity Disorder (DID) also experience AVH18 . One study found that people with Dissociative Identity Disorder experienced their voices as more internal, louder, and uncontrollable compared to people with Schizophrenia Spectrum Disorders (SSD). DID participants also showed more symptoms of thought disorder.

When considering factors like sex, depersonalisation (a type of dissociation), and child maltreatment, the differences in the location and origin of voices, and derailment, remained. However, there were no longer differences in the loudness or controllability of the voices. People with schizophrenia reported more distress, unusual beliefs about the voices, and more confusion in their thoughts and speech when these factors were taken into account19.

Neurocognitive Underpinnings of Auditory Hallucinations

The Feed-Forward Model20 helps explain auditory hallucinations by suggesting that the brain sends a copy of planned actions to the sensory cortex to predict their sensory feedback. When actual sensory feedback matches the prediction, the brain pays less attention. However, if there’s a mismatch, the brain becomes more aware.

In the context of auditory hallucinations, a significant mismatch between predicted and actual feedback can make the brain treat self-generated sounds as external. This increased activation in the sensory cortex can lead to hearing voices that seem to come from outside.

The study by Waters, et al.21 suggests that auditory hallucinations occur due to a combination of intense brain activity creating sounds and the brain having trouble correctly identifying and managing these sounds due to various cognitive issues. Here’s a simple explanation:

  1. Abnormal Brain Activity: Some parts of the brain become overly active and create strong, noticeable sounds or voices.
  2. Top-Down Mechanisms: The brain processes and interprets these sounds using several factors:
    • Signal Detection Errors: The brain mistakenly thinks these internal sounds are coming from the outside.
    • Executive and Inhibition Deficits: Problems with the brain’s control functions make it hard to manage and suppress these sounds.
    • Expectations and Memories: Past experiences and what the person expects to hear influence how these sounds are understood.
    • State Characteristics: The person’s current mental state (like stress or fatigue) affects how they perceive and interpret these sounds.

Neurotransmitters

In regards to the glutamatergic system, studies show elevated levels of glutamate (the most abundant excitatory neurotransmitter22 in your brain and central nervous system) and glutamine metabolites in the temporal and frontal brain regions of individuals diagnosed with schizophrenia with frequent and severe auditory hallucinations23. In addition, studies with ketamine show that drugs which alter glutamatergic neurotransmission are also capable of producing auditory hallucinations24.

Brain Injury and Impairment

Braun et al. looked at cases where people had tumors or lesions to the temporal lobe25, brainstem26 or thalamus27 that caused them to experience hallucinations in just one sense, like only seeing, hearing, or feeling things that aren’t there. They focused on reports where these hallucinations happened in only one of these senses. They found that the brain injury was almost always in the part of the brain responsible for that specific sense.

In healthy people, certain brain circuits help keep sensory experiences in check. When there’s an injury, these circuits don’t work properly, and the brain might overreact, causing hallucinations. This kind of hallucination is called a “release” form because the brain releases or unleashes these false perceptions.

Interestingly, people with these hallucinations often know they aren’t real. This is different from “dream centers” causing hallucinations. Instead, researchers think that dreaming itself is a special kind of “release” where the brain lets out these vivid sensory experiences.

Moreoever, a study by Lannotti et al.28, demonstrates that effective self-other voice discrimination relies on a neural network involving insula29, cingulate cortex30, and medial temporal lobe31 structures, and that impairments in these networks could underlie difficulties in distinguishing self-generated voices from others, potentially contributing to symptoms like auditory-verbal hallucinations.

Conclusion

In conclusion, auditory hallucinations, while often associated with psychiatric conditions like schizophrenia, are more common in the general population than many realise. They can occur without other psychotic symptoms and may be caused by a range of conditions, from social isolation and trauma to borderline personality disorder and brain injuries. The nature of these hallucinations differs significantly between clinical and nonclinical populations, with the former experiencing more distressing and intrusive episodes.

Understanding the underlying causes and mechanisms of auditory hallucinations is crucial. Psychological factors such as trauma and anxiety play significant roles, with neurocognitive models like the Aberrant Memory Model and the Feed-Forward Model providing insights into how the brain’s processing errors can lead to these experiences. Additionally, neurotransmitter imbalances and brain injuries further illustrate the complex interplay of biological and psychological factors contributing to auditory hallucinations.

This broader understanding challenges the stigma often associated with hearing voices and emphasises the need for a nuanced approach to treatment and support. By recognising the diverse causes and experiences of auditory hallucinations, we can better support those affected, whether they are part of the clinical or nonclinical population.

References

  1. Iris EC Sommer, Kirstin Daalman, Thomas Rietkerk, Kelly M. Diederen, Steven Bakker, Jaap Wijkstra, Marco P. M. Boks, Healthy Individuals With Auditory Verbal Hallucinations; Who Are They? Psychiatric Assessments of a Selected Sample of 103 Subjects, Schizophrenia Bulletin, Volume 36, Issue 3, May 2010, Pages 633–641, https://doi.org/10.1093/schbul/sbn130 ↩︎
  2. Maijer K, Begemann MJH, Palmen SJMC, Leucht S, Sommer IEC. Auditory hallucinations across the lifespan: a systematic review and meta-analysis. Psychological Medicine. 2018;48(6):879-888. doi:10.1017/S0033291717002367 ↩︎
  3. Choong, C., Hunter, M.D. & Woodruff, P.W.R. Auditory hallucinations in those populations that do not suffer from schizophrenia. Curr Psychiatry Rep 9, 206–212 (2007). https://doi.org/10.1007/s11920-007-0020-z ↩︎
  4. a network of bodily systems and sense organs that receive information and then process it. ↩︎
  5. Hoffman, 2007 cited in Waters F, Blom JD, Jardri R, Hugdahl K, Sommer IEC. Auditory hallucinations, not necessarily a hallmark of psychotic disorder. Psychological Medicine. 2018;48(4):529-536. doi:10.1017/S0033291717002203 Link ↩︎
  6. Tracy, D.K.; Shergill, S.S. Mechanisms Underlying Auditory Hallucinations—Understanding Perception without Stimulus. Brain Sci. 2013, 3, 642-669. https://doi.org/10.3390/brainsci3020642 ↩︎
  7. Campbell & Morrison, 2007 cited in Waters F, Blom JD, Jardri R, Hugdahl K, Sommer IEC. Auditory hallucinations, not necessarily a hallmark of psychotic disorder. Psychological Medicine. 2018;48(4):529-536. doi:10.1017/S0033291717002203 Link ↩︎
  8. Slotema et al. 2018 Link ↩︎
  9. Beatson, Josephine A. FRANZCP; Broadbear, Jillian H. PhD; Duncan, Charlotte FRANZCP; Bourton, David BSc; Rao, Sathya FRANZCP. Avoiding Misdiagnosis When Auditory Verbal Hallucinations Are Present in Borderline Personality Disorder. The Journal of Nervous and Mental Disease 207(12):p 1048-1055, December 2019. | DOI: 10.1097/NMD.0000000000001073 Link ↩︎
  10. Beatson J. Borderline personality disorder and auditory verbal hallucinations. Australasian Psychiatry. 2019;27(6):548-551. doi:10.1177/1039856219859290 ↩︎
  11. Kingdon, David G. MD, FRCPsych*; Ashcroft, Katie DClinPsychol†; Bhandari, Bharathi MRCPsych†; Gleeson, Stefan MRCPsych†; Warikoo, Nishchint MRCPsych†; Symons, Matthew MRCPsych†; Taylor, Lisa BM, BSc†; Lucas, Eleanor MRCPsych†; Mahendra, Ravi MRCPsych†; Ghosh, Soumya MRCPsych†; Mason, Anthony MRCPsych†; Badrakalimuthu, Raja MRCPsych†; Hepworth, Claire BSc†; Read, John PhD‡; Mehta, Raj BSc§. Schizophrenia and Borderline Personality Disorder: Similarities and Differences in the Experience of Auditory Hallucinations, Paranoia, and Childhood Trauma. The Journal of Nervous and Mental Disease 198(6):p 399-403, June 2010. | DOI: 10.1097/NMD.0b013e3181e08c27 Link ↩︎
  12. Slotema CW, Daalman K, Blom JD, Diederen KM, Hoek HW, Sommer IEC. Auditory verbal hallucinations in patients with borderline personality disorder are similar to those in schizophrenia. Psychological Medicine. 2012;42(9):1873-1878. doi:10.1017/S0033291712000165 Link ↩︎
  13. Beatson, Josephine A. FRANZCP; Broadbear, Jillian H. PhD; Duncan, Charlotte FRANZCP; Bourton, David BSc; Rao, Sathya FRANZCP. Avoiding Misdiagnosis When Auditory Verbal Hallucinations Are Present in Borderline Personality Disorder. The Journal of Nervous and Mental Disease 207(12):p 1048-1055, December 2019. | DOI: 10.1097/NMD.0000000000001073 Link ↩︎
  14. Beatson J. Borderline personality disorder and auditory verbal hallucinations. Australasian Psychiatry. 2019;27(6):548-551. doi:10.1177/1039856219859290 ↩︎
  15. Beatson, Josephine A. FRANZCP; Broadbear, Jillian H. PhD; Duncan, Charlotte FRANZCP; Bourton, David BSc; Rao, Sathya FRANZCP. Avoiding Misdiagnosis When Auditory Verbal Hallucinations Are Present in Borderline Personality Disorder. The Journal of Nervous and Mental Disease 207(12):p 1048-1055, December 2019. | DOI: 10.1097/NMD.0000000000001073 Link ↩︎
  16. Kingdon, David G. MD, FRCPsych*; Ashcroft, Katie DClinPsychol†; Bhandari, Bharathi MRCPsych†; Gleeson, Stefan MRCPsych†; Warikoo, Nishchint MRCPsych†; Symons, Matthew MRCPsych†; Taylor, Lisa BM, BSc†; Lucas, Eleanor MRCPsych†; Mahendra, Ravi MRCPsych†; Ghosh, Soumya MRCPsych†; Mason, Anthony MRCPsych†; Badrakalimuthu, Raja MRCPsych†; Hepworth, Claire BSc†; Read, John PhD‡; Mehta, Raj BSc§. Schizophrenia and Borderline Personality Disorder: Similarities and Differences in the Experience of Auditory Hallucinations, Paranoia, and Childhood Trauma. The Journal of Nervous and Mental Disease 198(6):p 399-403, June 2010. | DOI: 10.1097/NMD.0b013e3181e08c27 Link ↩︎
  17. Beatson, Josephine A. FRANZCP; Broadbear, Jillian H. PhD; Duncan, Charlotte FRANZCP; Bourton, David BSc; Rao, Sathya FRANZCP. Avoiding Misdiagnosis When Auditory Verbal Hallucinations Are Present in Borderline Personality Disorder. The Journal of Nervous and Mental Disease 207(12):p 1048-1055, December 2019. | DOI: 10.1097/NMD.0000000000001073 Link ↩︎
  18. Dorahy, Martin J. DClinPsych†; Shannon, Ciarán DClinPsych‡§; Seagar, Lenaire RN†; Corr, Mary DClinPsych¶; Stewart, Kellie MSc∥; Hanna, Donncha PhD§; Mulholland, Ciaran MRCPsych*††; Middleton, Warwick MD†. Auditory Hallucinations in Dissociative Identity Disorder and Schizophrenia With and Without a Childhood Trauma History: Similarities and Differences. The Journal of Nervous and Mental Disease 197(12):p 892-898, December 2009. | DOI: 10.1097/NMD.0b013e3181c299ea Link ↩︎
  19. Dorahy et al. 2023 Link ↩︎
  20. Tracy, D.K.; Shergill, S.S. Mechanisms Underlying Auditory Hallucinations—Understanding Perception without Stimulus. Brain Sci. 2013, 3, 642-669. https://doi.org/10.3390/brainsci3020642 ↩︎
  21. Flavie Waters, Paul Allen, André Aleman, Charles Fernyhough, Todd S. Woodward, Johanna C. Badcock, Emma Barkus, Louise Johns, Filippo Varese, Mahesh Menon, Ans Vercammen, Frank Larøi, Auditory Hallucinations in Schizophrenia and Nonschizophrenia Populations: A Review and Integrated Model of Cognitive Mechanisms, Schizophrenia Bulletin, Volume 38, Issue 4, 18 June 2012, Pages 683–693, https://doi.org/10.1093/schbul/sbs045 ↩︎
  22. Excitatory neurotransmitters “excite” the neuron and cause it to “fire off the message,” meaning, the message continues to be passed along to the next cell (Cleveland Clinic, 2022). Learn more about neurotransmitters. ↩︎
  23. Hayward et al. 2009, Hugdahl et al. 2015, Ćurčić-Blake et al. 2017 cited in Waters F, Blom JD, Jardri R, Hugdahl K, Sommer IEC. Auditory hallucinations, not necessarily a hallmark of psychotic disorder. Psychological Medicine. 2018;48(4):529-536. doi:10.1017/S0033291717002203 Link ↩︎
  24. Corlett et al. 2011 cited in Waters F, Blom JD, Jardri R, Hugdahl K, Sommer IEC. Auditory hallucinations, not necessarily a hallmark of psychotic disorder. Psychological Medicine. 2018;48(4):529-536. doi:10.1017/S0033291717002203 Link ↩︎
  25. plays a role in managing your emotions, processing information from your senses, storing and retrieving memories, and understanding language (Cleveland Clinic, 2023). ↩︎
  26. connects your brain to your spinal cord (Cleveland Clinic, 2024) ↩︎
  27. known as a relay station of all incoming motor (movement) and sensory information — hearing, taste, sight and touch (but not smell) — from your body to your brain (Cleveland Clinic, 2022). ↩︎
  28. Giannina Rita Iannotti, Pavo Orepic, Denis Brunet, Thomas Koenig, Sixto Alcoba-Banqueri, Dorian F A Garin, Karl Schaller, Olaf Blanke, Christoph M Michel, EEG Spatiotemporal Patterns Underlying Self-other Voice Discrimination, Cerebral Cortex, Volume 32, Issue 9, 1 May 2022, Pages 1978–1992, https://doi.org/10.1093/cercor/bhab329 ↩︎
  29. important for sensorimotor processing and auditory functioning ↩︎
  30. involved in processing emotions and behaviour regulation. It also helps to regulate autonomic motor function. ↩︎
  31. contains several structures related to important cognitive and emotional functions such as the formation of memories and spatial cognition. ↩︎