It is largely a mystery how our brains can conjure sights and sounds out of thin air. In this blog post, we will explore the neuroscience behind hallucinations and how 1 in 20 people experience them (Oxford Academic). The National Institutes of Health (NIH) defines hallucinations as false perceptions that seem real but occur without external stimuli. Today, hallucinations are common among those with schizophrenia, where 60-70% of patients experience auditory hallucinations and 70% experience visual hallucinations (NHS). Hallucinations are also found among healthy individuals, where 7-30% (NIH) of youth report in community surveys that they have experienced it. To delve into the neurological causes of hallucinations, it is first important to understand the variety in which they may manifest.
Visual hallucinations include seeing objects, people, animals, shapes, light flashes, or distortions that are not real. This is more common among those with schizophrenia, Parkinson’s, migraines, and brain tumors. Auditory hallucinations involve hearing things that don't exist, often conversations or commands. These hallucinations exist among those with schizophrenia, bipolar disorder, PTSD, or experience hearing loss and drug use. The false feeling of sensations on the skin is known as tactile hallucinations, which is common among those with schizophrenia, drug use, delirium tremens, and neurodegenerative diseases like Alzheimer’s. Other forms of hallucinations include olfactory, linked to head injury, sinus issues, and brain tumors; gustatory, having a metallic taste and experienced among those with temporal lobe epilepsy and sinus disease; and presence and proprioceptive hallucinations, where the feeling that someone is nearby or self-movement is experienced.
While much of the source of hallucinations stems from physiological factors from the brain, certain life events, including trauma or grief, and one’s cultural context can influence hallucinations. For instance, the belief that seeing things that are not real are divine experiences, having mourning rituals, or practicing hallucinations are all cultural factors that normalize and even glorify these strange experiences.
In terms of the neurological components, hallucinations are majorly the result of brain lesions from damage in sensory pathways. One example is the Charles Bonnet syndrome, where visual hallucinations arise from vision pathway damage, otherwise known as macular degeneration. According to the NIH, neuroimaging studies in schizophrenia have shown that there are structural and functional changes in brain areas associated with sensory processing. Gray matter is present in places like the superior temporal gyrus (STG), which is important for auditory processing, and the altered connection between temporal and frontal brain regions is shown to cause hallucinations. These mysteries might therefore stem from poor communication in brain networks. Furthermore, overactivity in auditory cortices and poor regulation from frontal brain areas are the main sources of auditory hallucinations.
There are a variety of treatment options for those experiencing chronic hallucinations, and many are targeted towards specific types of hallucinations. Repetitive Transcranial Magnetic Stimulation (rTMS) targets the temporoparietal cortex and has shown relative success in reducing auditory hallucinations. This is a relatively new method of treatment and has effectiveness close to antipsychotic medications. Cognitive behavioral therapy is a common form of treatment for most types of hallucinations, where therapists ease the minds of patients, normalizing their hallucinations and developing coping techniques to reduce their impact. The therapist also emphasizes reducing fear and distress when experiencing hallucinations and reinforces the idea that hallucinations are brain misfires, rather than threats. Antipsychotic drugs are more helpful for schizophrenia or dementia-related hallucinations and anti-seizure drugs are targeted towards epilepsy-related hallucinations. Triptans, beta-blockers, and anticonvulsants are used to treat migraines that may be a result of hallucinations. In terms of lifestyle changes, regular sleep and avoiding alcohol and drugs are recommended and enforced. There is a large emphasis on managing stress, as stress is another main component of hallucinations.
Works Cited
Alzheimer's Society. “Hallucinations in People with Dementia.” Alzheimer’s Society, 2019, www.alzheimers.org.uk/about-dementia/symptoms-and-diagnosis/hallucinations.
Boksa, Patricia. “On the Neurobiology of Hallucinations.” Journal of Psychiatry & Neuroscience : JPN, vol. 34, no. 4, July 2009, p. 260, pmc.ncbi.nlm.nih.gov/articles/PMC2702442/.
CBS News. “How Common Are Hallucinations?” Cbsnews.com, 28 May 2015, www.cbsnews.com/news/how-common-are-hallucinations/.
National Health Service. “Hallucinations and Hearing Voices.” Nhs.uk, 3 Feb. 2021, www.nhs.uk/mental-health/feelings-symptoms-behaviours/feelings-and-symptoms/hallucinations-hearing-voices/.
Waters, Flavie, and Charles Fernyhough. “Hallucinations: A Systematic Review of Points of Similarity and Difference across Diagnostic Classes.” Schizophrenia Bulletin, vol. 43, no. 1, 21 Nov. 2017, pp. 32–43, https://doi.org/10.1093/schbul/sbw132.
תגובות