Patients with a history of seizures reported experiencing hallucinations


Researchers from Trinity College Dublin and the Royal College of Surgeons in Ireland (RCSI) have shown for the first time, the mental health significance of hallucinations in people with a history of seizures.

In a study published today, findings show that 8% of individuals with a history of seizures report hallucinations, including experiences of hearing or seeing things that are not based in reality.

And, most importantly of that 8%, 65% also met criteria for one or more mental health disorders and 53% had one or more suicide attempt.

The study is published in leading journal Epilepsia. As part of one of the longest running studies of mental health in the general population, researchers assessed a wide range of physical and mental health factors in 15,000 people living in the UK. Hallucinations are known to occur in a proportion of adults with seizures but may be erroneously viewed as ‘incidental’ symptoms of abnormal electrical activity in the brain and nothing more.

The findings of this study tell us that these symptoms are not just incidental in people with seizures; they are important markers of risk for mental ill health and for suicidal behaviour.

Dr Ian Kelleher, Research Associate Professor of Psychiatry, Trinity and Senior Author of the study said:

” People with epilepsy are known to be at increased risk of suicide. But among individuals with seizures, it’s hard to pick out who is most at risk. What this research shows is that people with seizures who report hallucinations are a particularly high-risk group for suicidal behaviour – about half of these individuals had one or more suicide attempt.

So, it’s important in epilepsy clinics to ask about hallucinations – and where someone endorses these symptoms, to carefully examine their mental state.”

In an Irish context, anecdotal evidence tells us that auditory and visual hallucinations are not routinely assessed in epilepsy clinics.

Kathryn Yates, RCSI, Study Author said:

“It’s not surprising that individuals with seizures have a higher rate of hallucinations – almost any disease that affects the brain is likely to increase risk of hallucinations.

However, it’s important to recognise that hallucinations don’t simply reflect abnormal electrical activity in individuals with epilepsy; they’re important markers of risk for mental health problems and suicidal behaviour.”

Dr Kelleher concluded:

“We’ll need further research to fully understand the significance of hallucinations in people with seizures.

But what’s clear from this work is that, for clinicians working with people with seizures, asking about auditory and visual hallucinations should be a routine part of their assessment.”

Hallucinations—erroneous perceptions that are not elicited by external stimuli—may manifest in every sensory modality1. In schizophrenia, auditory hallucinations (AHs) have been described as the dominant experiences, with occurrence rates ranging from 60% to 80%2.

Although visual hallucinations (VHs) have been largely neglected in psychiatric disorders, a systematic review showed evidence of a weighted mean of 27% of VHs in schizophrenia3.

In contrast to what can be observed in neurological or eye diseases, schizophrenia is characterized by very rare isolated VHs4, which typically co-occur with hallucinations in other sensory modalities5,6,7,8,9, notably with auditory hallucinations in up to 84% (later called “A+VH”10).

Impairments of the hippocampus, a medial temporal structure involved in mnesic and neuroplastic processes, have been repeatedly reported in schizophrenia.

Such changes include reductions in volume, increases in basal perfusion, activation deficits during declarative memory, and reductions in neurogenesis in the dentate gyrus (for a recent review, see ref. 11).

More precisely, hippocampal hyperactivity was regularly associated with auditory12,13, visual14, or multisensory hallucinations15. Beyond a strict local alteration, disrupted hippocampal oscillations were linked to functional changes in hallucinations-related network16, while we observed specific structural and functional hippocampal dysconnectivity patterns in patients with audio–visual hallucinations17.

The fact that some schizophrenia patients experience pure AH or A+VH experiences has been related to developmental factors. Several studies reported that the rate of VHs in schizophrenia was age-dependent18,19,20, and some authors proposed that they could be considered as a severity index of developmental abnormalities19, a theory in line with the neurodevelopmental model of schizophrenia, which considers this disorder as the end state of abnormal brain development starting years before its onset21.

This hypothesis was recently supported by the association of VHs with impaired cortical sulcation22, an indirect proxy of early deviations in brain development23,24.

Surprisingly, the question of a possible neurodevelopmental origin of hippocampal impairments in VHs has never been investigated. A classic marker of early atypical hippocampal development is incomplete hippocampal inversion (IHI)25,26,27.

IHI is a variant of the hippocampus anatomy, in which prominent features are round, verticalized, and medially positioned hippocampus28,29. Different terms have been used to refer to this atypical pattern, including “hippocampal malrotation”30,31,32, “abnormal hippocampal formation”29, or “developmental changes of the hippocampal formation”28.

IHI has been described in patients with seizures (with a prevalence of ~30–50%), particularly in the case of impaired cortical development and in temporal lobe epilepsy28,29,33,34.

However, IHI is not specific to epilepsy and has also been reported in healthy individuals, although with a lower frequency25,29,35. A recent study assessed the prevalence of IHI in the general population in a large sample of over 2000 subjects and reported more frequent IHIs in the left (17%) than in the right (6%) hemispheres36.

In this context, this study aimed to test the hypothesis of a neurodevelopmental hippocampal deviation specifically associated with VHs in schizophrenia. We compared healthy volunteers with two subgroups of carefully selected seizure-free schizophrenia patients experiencing frequent hallucinations: patients with pure AH (i.e., patients who had never reported visual hallucinations) and patients with A+VH. The matched subgroups of patients differed only in the presence or absence of VHs. This distinction appears crucial in testing for variable IHI in patients with hallucinations according to the sensory modality involved.


  1. 1.Jardri, R., Cachia, A., Thomas, P., Pins, D. (eds). in The Neuroscience of Hallucinations, pp. 43–57 (Springer, NY, 2013).
  2. 2.Andreasen, N. C. & Flaum, M. Schizophrenia: the characteristic symptoms. Schizophr. Bull. 17, 27–49 (1991).Article CAS PubMed PubMed Central Google Scholar 
  3. 3.Waters, F. et al. Visual hallucinations in the psychosis spectrum and comparative information from neurodegenerative disorders and eye disease. Schizophr. Bull. 40(Suppl 4), S233–S245 (2014).Article PubMed PubMed Central Google Scholar 
  4. 4.Dudley, R., Aynsworth, C., Cheetham, R., McCarthy-Jones, S. & Collerton, D. Prevalence and characteristics of multi-modal hallucinations in people with psychosis who experience visual hallucinations. Psychiatry Res. 269, 25–30 (2018).Article PubMed PubMed Central Google Scholar 
  5. 5.Bracha, H. S., Wolkowitz, O. M., Lohr, J. B., Karson, C. N. & Bigelow, L. B. High prevalence of visual hallucinations in research subjects with chronic schizophrenia. Am. J. Psychiatry 146, 526–528 (1989).Article CAS PubMed PubMed Central Google Scholar 
  6. 6.Frieske, D. A. & Wilson, W. P. Formal qualities of hallucinations: a comparative study of the visual hallucinations in patients with schizophrenic, organic, and affective psychoses. Proc. Annu. Meet. Am. Psychopathol. Assoc. 54, 49–62 (1966).CAS PubMed PubMed Central Google Scholar 
  7. 7.Goodwin, D. W., Alderson, P. & Rosenthal, R. Clinical significance of hallucinations in psychiatric disorders. A study of 116 hallucinatory patients. Arch. Gen. Psychiatry 24, 76–80 (1971).Article CAS PubMed PubMed Central Google Scholar 
  8. 8.Lim, A., Hoek, H. W., Deen, M. L. & Blom, J. D., GROUP Investigators. Prevalence and classification of hallucinations in multiple sensory modalities in schizophrenia spectrum disorders. Schizophr. Res. 176, 493–499 (2016).Article PubMed PubMed Central Google Scholar 
  9. 9.Clark, M. L., Waters, F., Vatskalis, T. M. & Jablensky, A. On the interconnectedness and prognostic value of visual and auditory hallucinations in first-episode psychosis. Eur. Psychiatry 41, 122–128 (2017).Article CAS PubMed PubMed Central Google Scholar 
  10. 10.Mueser, K. T., Bellack, A. S. & Brady, E. U. Hallucinations in schizophrenia. Acta Psychiatr. Scand. 82, 26–29 (1990).Article CAS PubMed PubMed Central Google Scholar 
  11. 11.Lieberman, J. A. et al. Hippocampal dysfunction in the pathophysiology of schizophrenia: a selective review and hypothesis for early detection and intervention. Mol. Psychiatry 23, 1764–1772 (2018).Article CAS PubMed PubMed Central Google Scholar 
  12. 12.Diederen, K. M. J. et al. Deactivation of the parahippocampal gyrus preceding auditory hallucinations in schizophrenia. Am. J. Psychiatry 167, 427–435 (2010).Article PubMed PubMed Central Google Scholar 
  13. 13.Jardri, R., Pouchet, A., Pins, D. & Thomas, P. Cortical activations during auditory verbal hallucinations in schizophrenia: a coordinate-based meta-analysis. Am. J. Psychiatry 168, 73–81 (2011).Article PubMed PubMed Central Google Scholar 
  14. 14.Behrendt, R.-P. Hallucinatory experience as aberrant event memory formation: implications for the pathophysiology of schizophrenia. Prog. Neuropsychopharmacol. Biol. Psychiatry 71, 203–209 (2016).Article CAS PubMed PubMed Central Google Scholar 
  15. 15.Lefebvre, S. et al. Network dynamics during the different stages of hallucinations in schizophrenia. Hum. Brain Mapp. 37, 2571–2586 (2016).Article PubMed PubMed Central Google Scholar 
  16. 16.Hare, S. M. et al. Disrupted network cross talk, hippocampal dysfunction and hallucinations in schizophrenia. Schizophr. Res. 199, 226–234 (2018).Article PubMed PubMed Central Google Scholar 
  17. 17.Amad, A. et al. The multimodal connectivity of the hippocampal complex in auditory and visual hallucinations. Mol. Psychiatry 19, 184–191 (2014).Article CAS PubMed PubMed Central Google Scholar 
  18. 18.Bauer, S. M. et al. Culture and the prevalence of hallucinations in schizophrenia. Compr. Psychiatry 52, 319–325 (2011).Article PubMed PubMed Central Google Scholar 
  19. 19.David, C. N. et al. Childhood onset schizophrenia: high rate of visual hallucinations. J. Am. Acad. Child Adolesc. Psychiatry 50, 681–686.e3 (2011).Article PubMed PubMed Central Google Scholar 
  20. 20.Lowe, G. R. The phenomenology of hallucinations as an aid to differential diagnosis. Br. J. Psychiatry 123, 621–633 (1973).Article CAS Google Scholar 
  21. 21.Rapoport, J. L., Giedd, J. N. & Gogtay, N. Neurodevelopmental model of schizophrenia: update 2012. Mol. Psychiatry 17, 1228–1238 (2012).Article CAS PubMed PubMed Central Google Scholar 
  22. 22.Cachia, A. et al. Deviations in cortex sulcation associated with visual hallucinations in schizophrenia. Mol. Psychiatry 20, 1101–1107 (2015).Article CAS Google Scholar 
  23. 23.Cachia, A. et al. Longitudinal stability of the folding pattern of the anterior cingulate cortex during development. Dev. Cogn. Neurosci. 19, 122–127 (2016).Article CAS PubMed PubMed Central Google Scholar 
  24. 24.Mangin, J.-F., Jouvent, E. & Cachia, A. In-vivo measurement of cortical morphology: means and meanings. Curr. Opin. Neurol. 23, 359–367 (2010).PubMed Google Scholar 
  25. 25.Bajic, D. et al. Incomplete inversion of the hippocampus–a common developmental anomaly. Eur. Radiol. 18, 138–142 (2008).Article Google Scholar 
  26. 26.Raininko, R. & Bajic, D. ‘Hippocampal malrotation’: no real malrotation and not rare. AJNR Am. J. Neuroradiol. 31, E39 (2010).Article CAS Google Scholar 
  27. 27.Righini, A. et al. Hippocampal infolding angle changes during brain development assessed by prenatal MR imaging. AJNR Am. J. Neuroradiol. 27, 2093–2097 (2006).CAS PubMed Google Scholar 
  28. 28.Baulac, M. et al. Hippocampal developmental changes in patients with partial epilepsy: magnetic resonance imaging and clinical aspects. Ann. Neurol. 44, 223–233 (1998).Article CAS Google Scholar 
  29. 29.Bernasconi, N., Kinay, D., Andermann, F., Antel, S. & Bernasconi, A. Analysis of shape and positioning of the hippocampal formation: an MRI study in patients with partial epilepsy and healthy controls. Brain 128, 2442–2452 (2005).Article CAS Google Scholar 
  30. 30.Barsi, P. et al. Hippocampal malrotation with normal corpus callosum: a new entity? Neuroradiology 42, 339–345 (2000).Article CAS PubMed PubMed Central Google Scholar 
  31. 31.Gamss, R. P., Slasky, S. E., Bello, J. A., Miller, T. S. & Shinnar, S. Prevalence of hippocampal malrotation in a population without seizures. AJNR Am. J. Neuroradiol. 30, 1571–1573 (2009).Article CAS PubMed PubMed Central Google Scholar 
  32. 32.Peltier, B. et al. MRI of hippocampal malformations in patients with intractable temporal lobe epilepsy. J. Radio. 86, 69–75 (2005).Article CAS Google Scholar 
  33. 33.Bajic, D. et al. Incomplete hippocampal inversion-is there a relation to epilepsy? Eur. Radiol. 19, 2544–2550 (2009).Article PubMed PubMed Central Google Scholar 
  34. 34.Lehéricy, S. et al. Developmental abnormalities of the medial temporal lobe in patients with temporal lobe epilepsy. AJNR Am. J. Neuroradiol. 16, 617–626 (1995).PubMed PubMed Central Google Scholar 
  35. 35.Bronen, R. A. & Cheung, G. MRI of the temporal lobe: normal variations, with special reference toward epilepsy. Magn. Reson Imaging 9, 501–507 (1991).Article CAS PubMed PubMed Central Google Scholar



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