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Dissociative Identity Disorder and Its Impact on the Brain

Author: Celeste Nachnani

Editors: Erin Vinson, Hailey Hunter

In this day and age, humans are well-equipped to detect their own consciousness rather than jump to conclusions, for example, a demon is possessing them. Lucky for us, modern science helps us better understand the idea that we are in control of our own minds. However, the human brain is still quite complex, which means there are a lot of opportunities for it to malfunction, especially in the form of disorders. One disorder that many are starting to raise awareness of is Dissociative Identity Disorder, known as DID. DID has been mistaken for other disorders in the past, but with modern research and technology, we know that DID has real biological impacts on the brain.

So, what exactly is DID? DID is a disorder in which a person generates two or more separate personalities to cope with a distressing situation. For example, physical or sexual trauma. A person dealing with the psychological consequences of a traumatic event may view it from an outside perspective. Each persona has different traits or backgrounds, and it controls the person's behavior when shifting into that personality. The other personas are more of a fragment of their original identity rather than an entirely different entity. Famous actress AnnaLynne McCord, who has opened up about her struggles with Dissociative Identity Disorder, described this experience as a fragmented identity, stating, “"You are not multiple personalities when you experience DID. You are fragmented versions of yourself. The reason that the brain splits in this regard, it's always a protective mechanism." (Mental Health: Multiple Personality Disorder, 2020)

Cases of DID have been around since 1584 and were once treated by exorcisms. One example is the case of Jeanne Fery. She appeared to have created multiple personalities with different sets of knowledge and skills. In 1623, Sister Benedetta was another reported case of DID. She was allegedly possessed by three angelic boys. In 1880, Dr. Jean Martin Charcot originally called DID hystero-epilepsy. (History of Dissociative Identity Disorder, n.d.)

Symptoms of DID include anxiety, delusions, depression, disorientation, memory loss, and suicidal tendencies. Different personalities may generate different symptoms than others, resulting in a further lack of consistency of thought. DID could be mistaken for schizophrenia or bipolar disorder due to shared symptoms, but brain scans show this is not the case. (Dissociative Identity Disorder: What Is It, Symptoms & Treatment, 2021)

Additionally, someone with DID may have flashbacks to a traumatic experience in which they may experience a strengthened passive defense mode, tonic immobility, and increased parasympathetic activity. The parasympathetic nervous system regulates homeostasis, or calms the mind and body down after a stressful event.

Neuroimaging techniques such as magnetic resonance imaging (MRI), spectroscopy, positron emission tomography (PET), and diffusion tenor sensing (DTI) help professionals identify abnormalities in the brain. However, even though brain scans of brains with bipolar disorder are different from those with DID, the two disorders tend to get mixed up.

Image of Bipolar Disorder Brain Scan by Maicon Albuquerque on ResearchGate

DID Brain Scan from the British Journal of Psychiatry

DID Brain Scan uploaded in Dissociative part-dependent biopsychosocial reactions to backward masked angry and neutral faces: An fMRI study of dissociative identity disorder

What’s actually happening in the brains of people with DID? There may be a disconnection between the cortico-limbic brain system, which involves the amygdala, anterior cingulate cortex, and prefrontal structures. Studies have shown that these areas of the brain are involved in the perception and processing of (chronic) pain. The prefrontal cortex is in charge of decision-making. (Neugebauer, 2018). Processes in the brain in charge of decision-making tend to lack impulse control and reward evaluation. DID impacts the connectivity between the frontal cortex and basal ganglia, which may suppress attentional and emotional functions. (Dissociation and Alterations in Brain Function and Structure: Implications for Borderline Personality Disorder, 2017)

Furthermore, less arousal is experienced during pleasure or pain sensations and there is diminished activity in the occipital-temporal cortex and insula, which play important roles in the encoding of negative emotions, interoceptive awareness, and pain perception. Altered glucose metabolism due to DID in tempo-parietal regions of the brain plays a role in feeling unsettled and having a sense of altered consciousness when shifting personalities.

The stigma that surrounds DID has been prevalent in the past, which people are now actively dismantling. Some of these myths are that people with DID are unfaithful, violent, and can switch personalities on-demand (History of Dissociative Identity Disorder, n.d.). In fact, none of those myths are true.

Those with DID can receive forms of treatment through means such as psychotherapy, cognitive behavioral therapy, and dialectical behavioral therapy, helping them to integrate as one personality if they wish and lead a successful life.

Works Cited:

Bruises, B. A. (2021, December 17). DID Myths and Misconceptions. Beauty After Bruises.

Cognitive neuroscience and brain imaging in bipolar disorder. (2008). Developments in Bipolar Disorder, 10(2), 153–163.

Dissociative Disorders. (n.d.). NAMI. Retrieved January 6, 2022, from

Dissociative Identity Disorder: What Is It, Symptoms & Treatment. (2021, May 25). Cleveland Clinic. Retrieved January 6, 2022, from

History of Dissociative Identity Disorder. (n.d.). DID Research. Retrieved January 6, 2022, from

Mental Health: Multiple Personality Disorder. (2020, March 17). Vikram Hospital. Retrieved January 6, 2022, from

Dissociation and Alterations in Brain Function and Structure: Implications for Borderline Personality Disorder. (2017, January 30). NCBI. Retrieved January 6, 2022, from

Neugebauer, V. (2018, November 29). Cortico-limbic pain mechanisms. NCBI. Retrieved January 6, 2022, from



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