This MS-related group of symptoms is probably neglected in routine MS neurological practice and may fall through the cracks.

Key points

• Dissociative states in people with MS may arise for different reasons: organic (resulting from damage to the temporal and parietal lobes), psychogenic (following psychological trauma) or iatrogenic (induced by drug treatments).
• Such states range from transient feelings of unreality to recurring episodes of depersonalisation and/or derealisation. Other presentations may also occur.
• Depersonalisation feels like being detached from one’s own body or thoughts, feeling like an ‘outside observer’ of one’s life.
• Derealisation feels like being detached from the external world, which may appear foggy, dreamlike, lifeless or two-dimensional.
• In MS, dissociation often has a physical (organic) basis in the brain. This article explores the specific effects of damage to each of the four lobes of the human brain.
• Managing dissociative states in MS requires a dual approach: biological (treating the underlying MS disease) and psychological.
• To differentiate between physical and psychological causes, doctors must consider the possibility of an MS relapse, an infection or the effects of an MS-related treatment. Checks for balance, hearing and psychological screening are also needed.

Causes and range of dissociative states

People with MS have an elevated risk of experiencing dissociative phenomena that give rise to alterations of consciousness, self-perception and reality testing (being able to assess what is real versus what is imagined). These dissociative states − ranging from transient feelings of unreality to chronic depersonalisation−derealisation disorder (DPDR) and non-epileptic seizures − are often undiagnosed. They may arise for different reasons.

• Organic dissociation results from damage(lesions)to the temporal and parietal lobes, which can disrupt neural networks responsible for ‘embodied self-awareness’ (the constant experience of oneself through physical sensations, emotions and bodily signals).
• Psychogenic dissociative states can occur in people with MS following the psychological trauma of diagnosis and the high prevalence of comorbid post-traumatic stress disorder (PTSD).
• Iatrogenic dissociative states can be induced by drug treatments, particularly high-dose corticosteroids and psychoactive symptomatic treatments.

Dissociation is typically characterised by disruption in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control and behaviour.  The most frequently reported dissociative symptoms in the MS population fall under the spectrum of depersonalisation−derealisation.

Depersonalisation (the fragmentation of self)

Depersonalisation is characterised by a persistent or recurring feeling of being detached from one’s own body or thoughts. People with MS describe this as feeling like an ‘outside observer’ of their life, like watching oneself in a movie, or like a ‘robot’ with no control over their speech or actions. In MS, depersonalisation is associated with damage to the parietal lobe or the spinal cord – areas that help the brain detect body position and movement (proprioception). People with damage to these areas may feel as though a limb does not belong to them. This is not a delusion, because the person may see their limb move and intellectually know it is theirs. Rather, it is a sensory problem with the ‘body schema’ (the brain’s internal map of your body), that no longer matches your physical body.

Derealisation (the distortion of the world)

Derealisation involves a feeling of being detached from your surroundings. The external world may appear foggy, dreamlike, lifeless, colourless or artificially two-dimensional. Objects may appear distorted in size or shape; sounds may seem muted or distant. Derealisation is often worsened by sensory problems in people with MS (affecting sight, sound, touch, taste, smell or movement). Optic neuritis, a common early sign of MS, causes visual blurring, reduced colour intensity and visual field defects (gaps); see Colour vision and Driving at night. When the brain receives unclear visual input, it struggles to construct a vivid, real-feeling model of the environment, which can lead to a secondary sense of derealisation.

Problems with balance (vestibular dysfunction, leading to vertigo, dizziness and gait instability) are often associated with derealisation; conflicting signals from the eyes and inner ear can cause people with MS to feel disoriented. 

Non-epileptic seizures

Non-epileptic seizures, also referred to as dissociative seizures, resemble epileptic seizures − involving convulsive movements, apparent loss of consciousness and stiffening of the body. However, they are not caused by abnormal electrical activity in the brain (usually visible on an electroencephalogram) but are psychological, most likely a mechanism for managing distress or trauma. Care is needed to determine the correct cause in each individual because people with MS are actually at increased risk for epilepsy due to brain lesions. Studies of magnetic resonance imaging (MRI) scans suggest that damage in the right brain hemisphere or the frontal lobes may increase the risk of non-epileptic seizures.

Dissociative amnesia and brain fog

Dissociative amnesia is the inability to recall important personal information, far beyond ordinary forgetting. It is usually related to stress or trauma. In MS, this poses a diagnostic challenge because many patients already experience cognitive dysfunction that affects processing speed and working memory. A study differentiating organic (‘true’) memory loss from dissociative amnesia in MS found that people who reported memory problems often had high levels of dissociation and anxiety but did not show major problems on formal memory testing.¹ This implies that the ‘memory loss’ experienced by many people with MS may be an attention problem due to a mild dissociative state or emotional overload, rather than a result of permanent damage to memory structures in the brain.

Dissociative identity disorder

While rare, cases of dissociative identity disorder (DID) have been reported in people with MS. DID is characterised by the presence of two or more distinct personality states. Affected individuals typically have experienced childhood trauma, which makes them more prone to develop dissociation. A diagnosis of MS acts as a further stressor that challenges their sense of identity. Other symptoms of DID may include physical weakness and sensory loss, which can mimic an MS relapse and lead to misdiagnosis. 

Underlying disease processes in MS

In the general psychiatric population, dissociative disorders are usually regarded as psychological in origin. In MS, however, dissociation often has a physical basis in the brain. MS damages myelin (the protective covering of nerve fibres), severs nerve connections and affects grey matter, all of which disrupts communication between different brain regions. When these connections are broken, the brain cannot integrate sensation, emotion and thought into a conscious experience.

Structure of the brain, showing the left and right cerebral hemispheres (left) and the four lobes (frontal, parietal, temporal and occipital; right) in each cerebral hemisphere. Each individual lobe has particular key roles; however, they do not function in isolation but as part of a wider system of neural networks. From Gemini Pro.

Temporal lobe

The temporal lobes play a central role in processing memory and emotions as well as in combining auditory and visual information. MS-related damage in these areas is associated with psychiatric symptoms, including psychosis and dissociation. The temporal lobe also houses the limbic system, comprising the amygdala (which processes emotion) and the hippocampus (which supports memory). If there is damage to the white matter pathways between the limbic system and the frontal cortex (a region known as the uncinate fasciculus) or to sensory regions, the emotional content of experiences can be lost. For example, when a person with MS sees a familiar object or person, the visual cortex sends information to the limbic system, thus activating the appropriate emotional response (e.g. warmth, recognition). If MS disrupts this connection, the person may recognise the object but feel no emotional familiarity. This mismatch, i.e. recognition without feeling, is central to derealisation and to the jamais vu phenomenon (the strange feeling that something familiar is suddenly unfamiliar or new) that is often reported in temporal lobe disorders.

A sagittal (longitudinal) view of the human brain showing the interconnected network of the limbic system, a key regulator of emotion, memory and spatial navigation. From Gemini Pro 3.0.

Temporal lobe epilepsy

MS lesions in the temporal lobe can sometimes trigger epileptic activity. Even in the absence of full-blown convulsions, abnormal electrical activity there can cause ‘dreamy states,’ profound déjà vu or feelings of unreality similar to the warning phase (aura) of temporal lobe epilepsy. Symptoms of depersonalisation disorder overlap with those experienced in temporal lobe epilepsy, particularly unusual body experiences and memory distortions.

Parietal lobe

The parietal lobe combines sensory information from different sources to form a single perception (cognition) and helps the brain build a map of the body and the world around us. The brain constantly updates this map, or ‘body schema’, using signals from the spinal cord. MS lesions in the parietal lobe or spinal cord can interrupt this information and deprive the brain of body map data.

When the brain ceases to receive reliable input from a limb, because of MS-related damage, it may ‘dissociate’ that body part from its self-image. This can manifest as:

• asomatognosia (the inability to recognise a part of one’s own body)
• somatoparaphrenia (the delusion that a limb belongs to someone else)
• depersonalisation (see above).

Temporoparietal junction

The temporoparietal junction, where the temporal and parietal lobes meet, is a hub for integrating balance, visual and somatosensory signals to locate the ‘self’ in space. Electrical stimulation of this area can cause out-of-body experiences. In MS, lesions affecting the temporoparietal junction or the balance pathways in the brainstem can trigger dissociative events (for example, a feeling of floating above one’s body or viewing oneself from outside. These episodes are often linked to balance problems, suggesting that the brain is trying to make sense of conflicting signals.

Occipital lobe

The occipital lobe is the main visual processing centre of the brain. Damage in this region or in visual pathways can lead to complex visual distortions that trigger derealisation. ‘Alice in Wonderland Syndrome’ is a perceptual distortion in which objects appear much smaller (micropsia) or much larger (macropsia) than they really are. When damage from MS affects the visual association areas, vision may appear two-dimensional, with the world looking ‘flat’ or like a painted backdrop. This loss of depth perception contributes to the feeling of living in a movie or a simulation.

Clinico-radiological paradox

The clinico-radiological paradox refers to the discrepancy between the number and volume of MS lesions seen on MRI and a patient’s level of physical disability. Some people with MS have extensive brain lesions but relatively normal movement and minimal disability scores. While these patients may appear physically ‘fine’, lesions in high-level areas of the cortex (frontal, parietal and temporal lobes) can disrupt cognitive and emotional networks.  Such individuals may be at high risk for subjective dissociation − feeling fragmented or cognitively detached − while objective observers (and disability scales) fail to register any deficit. These hidden symptoms can worsen the patient’s sense of isolation and unreality.

Trauma-related causes

Receiving a diagnosis of MS

While localised MS lesions create the ‘hardware failure’ in the brain that enables dissociation, psychological factors often provide the ‘software trigger’. Receiving a diagnosis of MS may be considered a medical trauma, often involving invasive procedures (lumbar punctures), frightening MRI experiences (claustrophobia) and hospitalisations. These repeated exposures to threat and a feeling of helplessness and vulnerability can induce a state of chronic hyperarousal and subsequent dissociation, consistent with the dissociative subtype of PTSD. Many people with MS meet the diagnostic criteria for PTSD specifically related to their MS diagnosis and outlook (please see, How common is post-traumatic stress disorder in people with MS?). Developing an ongoing, incurable and potentially disabling neurological condition can shatter one’s expectations for the future. By detaching from the reality of their diagnosis, people with MS may attempt to shield themselves from overwhelming anxiety and grief. Dissociation serves as an adaptive defence mechanism – a ‘mental flight’ when physical flight is impossible. This sounds dramatic, but it may explain why some people with MS develop dissociative disorders. 

Childhood trauma

Research has demonstrated a potential relationship between childhood trauma, dissociation and the development of MS. Severe stress, neglect or abuse in childhood permanently dysregulates the hypothalamic−pituitary−adrenal axis (a system that is crucial for the body’s stress management). It consists of three organs that each release hormones to eventually raise cortisol levels in the body. This results in a chronic proinflammatory state and altered cortisol responses, which may increase biological susceptibility to developing MS later in life. Large-scale cohort studies indicate that women who experienced childhood abuse are significantly more likely to develop MS in the future.²

Treatment-related causes

The management of MS involves disease-modifying therapies (DMTs) and corticosteroids for acute relapse management. Many of these agents have significant neuropsychiatric side effects that can mimic, induce or exacerbate dissociative states.

Corticosteroids. High doses of the intravenous corticosteroid methylprednisolone (e.g. 1000 mg daily for 3−5 days) are the standard of care for speeding up the recovery from acute MS relapses. It is known to cause acute psychiatric adverse effects in many patients (dependent on the corticosteroid dose).  Symptoms often begin with insomnia and euphoria but can progress to severe mood lability, anxiety and frank dissociation and delirium. Patients may experience a ‘steroid high’ followed by a crash into depression; some develop acute psychosis with hallucinations and confusion. Corticosteroids enhance dopamine activity. They may cause acute, reversible reductions in hippocampal volume. Their effect on the brain presumably decouples the patient from reality, leading to a temporary dissociative or psychotic state that resolves upon tapering the steroid dosage.

Interferon-beta has a longstanding association with depression and anxiety. Interferons are cytokines that induce a proinflammatory response similar to ‘sickness behaviour,’ which includes social withdrawal, fatigue and anhedonia (inability to feel pleasure in activities that are usually considered to be pleasurable). They may also decrease serotonin levels in the brain. While direct dissociation is less common, the severe anxiety and depression induced by interferons presumably lower the threshold for the onset of stress-induced depersonalisation.

Natalizumab is a highly effective monoclonal antibody, but it carries specific risks. The ‘wearing off’ effect in the week preceding the next infusion can be characterised by intensifying fatigue, cognitive fog and mood instability, which may manifest as a feeling of detachment or unreality.  The most severe risk associated with natalizumab is progressive multifocal leukoencephalopathy; this causes extensive, rapid demyelination that can lead to confusion, personality changes and cognitive decline. These symptoms can be misinterpreted as psychiatric dissociation or dementia in the early stages.

Fingolimod, an S1P modulator, has been associated with posterior reversible encephalopathy syndrome. This condition involves swelling in the posterior brain regions (parietal/occipital lobes) caused by leakage of fluid from capillaries. It presents with acute confusion, visual changes, headaches and altered consciousness − a constellation of symptoms that could mimic derealisation and dissociation.

Symptomatic treatments. Abrupt withdrawal of baclofen and tizanidine, which are used for spasticity, can cause severe delirium, hallucinations and dissociation. Similarly, gabapentin and pregabalin, which are often used in people with MS to manage neuropathic pain, can cause sedation and cognitive clouding (‘zombie-like’ feeling) that contribute to depersonalisation.

Diagnosis

When someone with MS develops dissociative symptoms, doctors must first rule out physical (organic) causes before assuming the problem is purely psychological. A diagnostic algorithm should do the following.

1. Rule out an MS relapse Any new onset of psychiatric or dissociative symptoms warrants an MRI scan with gadolinium. New lesions in the temporal, parietal or frontal lobes can directly cause these symptoms. 2. Rule out infection Urinary tract infections are extremely common in MS and are the leading cause of acute confusional states (delirium) that can mimic dissociation. A urinalysis and a workup for other infections are mandatory. 3. Review medication Assess for recent steroid use, cumulative damage from anticholinergic drugs (e.g. for bladder dysfunction) or withdrawal from muscle relaxants (baclofen and tizanidine). 4. Check balance and hearing ‘Neuro-otological examination’ is a specialised assessment for dizziness, vertigo, hearing loss and balance disorders. Checking for nystagmus (uncontrollable eye movements) helps to diagnose balance disorders. Treating vertigo may resolve the derealisation. 5. Carry out psychological screening Your health professional can use the Dissociative Experiences Scale (DES-II) or the Dissociative Disorders Interview Schedule to quantify symptom severity. People with MS generally score in the normal range on DES-II unless they have comorbid DID or PTSD.

Differentiating organic from psychiatric dissociation is difficult. It may require referral to a neuropsychiatrist. MS-related brain fog or cognitive impairment with an organic basis is characterised by slowed processing speed, word-finding difficulties and fatigue. Patients try to engage but fail. In comparison, psychiatric dissociation is characterised by a subjective sense of detachment (‘I am not here’). Patients may have preserved processing speed but feel emotionally disconnected. As noted above, MS cog-fog often contains a dissociative component driven by anxiety. Treating the anxiety usually clears the ‘cog-fog’ more effectively than cognitive rehabilitation alone.

Management

Managing dissociative states in MS requires a dual approach: biological (i.e. treating the underlying MS disease) and psychological. 

Drug treatments

The primary prevention of organic dissociation involves preventing new lesion formation. High-efficacy DMTs are the best way to preserve brain volume and connectivity. Psychotropics such as selective serotonin reuptake inhibitors (e.g. fluoxetine, sertraline) can help manage the anxiety and depression that underlie DPDR. They may also help with MS-related fatigue. Antipsychotics (e.g. quetiapine, olanzapine) may be rarely indicated for managing steroid-induced psychosis or organic paranoia related to temporal lobe lesions. Lamotrigine and other anticonvulsants (e.g. carbamazepine and oxcarbazepine) can be used to treat both seizures and depersonalisation; they are particularly beneficial in patients with temporal lobe pathology. 

Psychological interventions

Cognitive behavioural therapy is the gold standard for treating DPDR. It helps patients reframe the terrifying sensation of ‘going crazy’ or ‘disappearing’ as a harmless (albeit distressing) symptom of anxiety or the disease. This reduces the catastrophic thinking that perpetuates the dissociation. 

Eye movement desensitisation and reprocessing (EMDR) can be effective for MS-related PTSD (medical trauma) or childhood trauma. However, standard EMDR can be overwhelming for patients with dissociation. Modified (e.g. ‘titrated’) EMDR protocols can prevent flooding the patient with traumatic memories before they have stabilisation skills. EMDR is available via some UK NHS psychiatric services. 

Grounding and mindfulness techniques (e.g. holding an ice cube, describing the environment) anchor the patient in the present moment and help them to manage acute episodes of derealisation. Mindfulness-based stress reduction has shown efficacy in improving the quality of life and reducing depressive symptoms in people with MS.

Vestibular rehabilitation therapy (VRT) is a specialised, exercise-based physical therapy designed to reduce vertigo, dizziness and imbalance. It should be offered to people with MS where derealisation is driven by vertigo. VRT helps the brain compensate for inner-ear deficits through personalised exercises that focus on gaze stabilisation, balance training and habituation. Physical therapy to improve balance and gaze stability can directly reduce the feeling of unreality. 

Conclusions

To self-manage dissociative states effectively, individuals with MS can proactively apply several key principles highlighted above. During acute episodes of derealisation or dissociation, employing practical grounding and mindfulness techniques – such as holding an ice cube or actively describing the immediate environment – can serve as vital tools to anchor oneself in the present moment. Furthermore, individuals can apply cognitive behavioural principles by ‘reframing’ their experiences. Recognising that terrifying feelings of ‘disappearing’ or ‘going crazy’ are often harmless symptoms of anxiety or the disease itself can help reduce the catastrophic thinking that perpetuates dissociation.

Effective self-management also involves staying vigilant about physical triggers (e.g. monitoring for signs of urinary tract infections or medication side effects) and pursuing targeted physical interventions, such as vestibular rehabilitation exercises, if feelings of unreality are driven by dizziness and balance issues. By combining these practical coping strategies with a clear understanding of the biological and psychological origins of their symptoms, individuals with MS can regain a sense of control and significantly reduce the impact of dissociative states on their daily lives.

References

1. Bruce J, et al. Self-reported memory problems in multiple sclerosis: influence of psychiatric status and normative dissociative experiences. Arch Clin Neuropsychol 2010;25:39–48.
2. Rehan ST, et al. Association of adverse childhood experiences with adulthood multiple sclerosis: A systematic review of observational studies. Brain Behav 2023;13:e3024.