I went on this trip once, back to my hometown after a long absence. Have you ever felt that your surroundings seem odd and distant, and that you're completely detached from them? That the things and places around you aren't real? This can happen to me, on occasion.
It did on this trip, perhaps because I've dreamed about those places so many times that the real places and the dream places are blurred in memory.
Of course time marches on. The stores in the strip mall have changed, and you go to Starbucks with your father. But sometimes new and surprising things appear in the landscape.
Or maybe old and unexpected things pop up in the background, renewing a long-standing confusion between rural and suburban.
These nostalgic travel vignettes illustrate the phenomenon of derealization, a subjective alteration in one's perception or experience of the outside world. The pervasive unreality of the external environment is a key feature, along with emotional blunting. The world loses its vividness, coloring, and tone. Some even report seeing things as if they're looking through a fog or a haze. Or a pane of blurry glass.
Derealization is often (but not always) associated with depersonalization, a feeling of detachment from oneself, as if you yourself are unreal or even outside your body. Both of these phenomena can be mild and transient, or the symptoms can be chronic and disturbing in Depersonalization Disorder, which is considered a dissociative disorder.
Not surprisingly, these dissociative states can be induced by drugs such as ketamine (a dissociative anesthetic) and hallucinogens (e.g., LSD, psilocybin). The symptoms can also be induced by stress and anxiety, or by trauma, or by sleep deprivation. Not all instances of derealization and depersonalization qualify as a disorder, however.
The DSM-5 diagnostic criteria for Depersonalization/Derealization Disorder are as follows:
A. An individual consistently has a feeling of both or either depersonalization or derealization.
B. "During the depersonalization or derealization experiences, reality testing remains intact."
- Depersonalization: Experiences of unreality, detachment, or being an outside observer with respect to one's thoughts, feelings, sensations, body, or actions (e.g.,perceptual alterations, distorted sense of time, unreal or absent self, emotional and/or physical numbing.)"
- Derealization: "Experiences of unreality or detachment with respect to surroundings (e.g., individuals or objects are experienced as unreal, dreamlike, foggy, lifeless, or visually distorted."
C. "The disturbance is not attributable to the physiological effects of a substance (e.g., a drug of abuse, medication or other medical condition (e.g., seizures)."
D. "The disturbance is not better explained by another mental disorder."
What other mental disorders can manifest as derealization (included as one of a core set of symptoms)? Among the most curious of these is an unusual neurological disorder called Kleine-Levin syndrome (KLS).
Imagine sleeping 20 hours a days for days end, with your limited waking hours spent confused, disoriented, cognitively impaired, and voraciously hungry. Sometimes referred to as “Sleeping Beauty” syndrome in the media, KLS is a very rare sleep disorder (1-2 cases per million) characterized by intermittent bouts of hypersomnia (Arnulf et al., 2012). Other symptoms can include hyperphagia (compulsive overeating), hypersexuality, apathy, behavioral disturbances, depression, delusions, and derealization.1
Considered a relapsing/remitting disease that typically onsets during adolescence, there is no known cause, no objective laboratory findings, and no cure. In the review by Arnulf et al. (2012), episodes lasted 10-12 days on average, followed by almost 6 months of normal sleep, cognition, and behavior. The disease can resolve spontaneously once the patient reaches their 30s. Those with childhood or adult onset can show a different disease course.
The review suggested that confusion, apathy, and/or derealization are the best diagnostic indicators, when coupled with recurrent hypersomnia.
The Phenomenology of Derealization in KLS
Since derealization is such a prominent symptom of KLS, Arnulf et al. (2012) provided examples reported by patients during Kleine-Levin episodes:
- Patients feel as though they are in a dream or a bubble
- They claim sight, sound, smell, taste, and perception of cold, hot, and pain feel wrong
- The environment feels flat and two-dimensional
- In the shower, patients might see the water flowing on their bodies, but not feel its temperature
- Patients who injure themselves might not understand when or how the injury happened or that it has happened at all
- Actions do not have consequences
- Patients might do something to test for a normal action, such as breaking an object (eg, a cup)
- Patients might ask whether they are dead or alive
Are there any changes in brain activity during symptomatic periods in KLS? A Paris-based research group led by Dr. Isabelle Arnulf recently reported on a functional imaging study in 41 asymptomatic patients (Kas et al., 2014), 11 of whom were also scanned during an episode. The authors used SPECT (single photon emission computed tomography) to measure blood perfusion in the brain. SPECT is a relatively inexpensive cousin of PET scanning, albeit with lower spatial resolution. Although there is a place for SPECT in nuclear medicine, it is not accepted as a method to diagnose psychiatric disorders, and Kas et al. did not treat it as such.
I found it remarkable that 11 patients were scanned during an episode, a phenomenal number considering the rarity of the disease and the nature of the presenting symptoms. In fact, two additional patients could not be scanned because they were so agitated and delusional. The patients completed questionnaires related to KLS symptoms, sleep disturbances, apathy, depression, and the Depersonalization/ Derealization Inventory (Cox and Swinson, 2002).
One major finding was reduced perfusion in the general region of the temporal-parietal junction (TPJ), which was associated with more severe symptoms of derealization. The TPJ has been related to multimodal sensory integration – the integration of information from the somatosensory system (body knowledge) and the external world (visual, auditory) – among other things (like theory of mind, attention, and language). Damage or dysfunction of the TPJ can result in out-of-body experiences (Blanke & Arzy, 2005).
Modified from Fig. 6 (Kas et al., 2014). Correlation between middle temporal perfusion and Derealization/Depersonalization Inventory scores during symptomatic periods. Plots show normalized brain perfusion values in (A) left TPJ region (x = 46, y = 66, z = 11, filled circles) and (B) right TPJ region (x = 38, y = 55, z = 25, open circles).
Changes in perfusion between episodes were also observed (relative to controls). KLS patients showed hypoperfusion in the hypothalamus, thalamus, caudate nucleus, and some cortical association areas that persisted during asymptomatic periods.
Although we must issue the appropriate caveats (small patient group, imprecise localization, limitations of the methodology etc.), the current results are suggestive of a neurological correlate of derealization. I'll keep this in mind the next time I visit my hometown after a long absence...
1 The KLS Foundation describes the following symptoms (for informational purposes only):
KLS patients would have symptom A, one or more of the B symptoms, and the pattern described in C.
A. Recurrent episodes of severe hypersomnia (2-31 days)
B. Plus one or more of the associated features:
C. Interspersed with long periods of normal sleep, cognition, behavior, mood
- Cognitive abnormalities such as feeling of unreality, confusion, hallucinations.
- Abnormal behavior such as irritability, aggression, odd behavior
- Binge eating
Arnulf, I., Rico, T., & Mignot, E. (2012). Diagnosis, disease course, and management of patients with Kleine-Levin syndrome. The Lancet Neurology, 11 (10), 918-928 DOI: 10.1016/S1474-4422(12)70187-4
Blanke O, Arzy S. (2005). The out-of-body experience: disturbed self-processing at thetemporo-parietal junction. Neuroscientist 11:16-24.
Kas, A., Lavault, S., Habert, M., & Arnulf, I. (2014). Feeling unreal: a functional imaging study in patients with Kleine-Levin syndrome. Brain DOI: 10.1093/brain/awu112
A few years ago I went on a trip back to my hometown after a long absence....
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