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Derealization or derealisation (sometimes abbreviated as DR) is an alteration in the perception or experience of the external world so that it seems unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional coloring and depth. It is a dissociative symptom of many conditions, such as psychiatric and neurological disorders, and not a standalone disorder.
Derealization is a subjective experience of unreality of the outside world, while depersonalization is unreality in one's sense of self. Although most authors currently regard derealization (surroundings) and depersonalization (self) as independent constructs, many do not want to separate derealization from depersonalization. The main reason for this is nosological, because these symptoms often co-occur, but there is another, more philosophical reason: the idea that the phenomenological experience of self, others, and world is one continuous whole. Thus, feelings of unreality may blend in and the person may puzzle over deciding whether it is the self or the world that feels unreal to them.
Chronic derealization may be caused by occipital–temporal dysfunction. These symptoms are common in the population, with a lifetime prevalence of up to 5% and 31–66% at the time of a traumatic event.
The detachment of derealization can be described as an immaterial substance that separates a person from the outside world, such as a sensory fog, pane of glass, or veil. Individuals may complain that what they see lacks vividness and emotional coloring. Emotional response to visual recognition of loved ones may be significantly reduced. Feelings of déjà vu or jamais vu are common. Familiar places may look alien, bizarre, and surreal. The world as perceived by the individual may feel like it is going through a dolly zoom effect. Such perceptual abnormalities may also extend to the senses of hearing, taste, and smell. The degree of familiarity one has with their surroundings is among one's sensory and psychological identity, memory foundation and history when experiencing a place. When a person is in a state of derealization, they block this identifying foundation from recall. This "blocking effect" creates a discrepancy of correlation between one's perception of one's surroundings during a derealization episode, and what that same individual would perceive in the absence of a derealization episode.
Frequently, derealization occurs in the context of constant worrying or 'intrusive thoughts' that one finds hard to switch off. In such cases it can build unnoticed along with the underlying anxiety attached to these disturbing thoughts, and be recognized only in the aftermath of a realization of crisis, often a panic attack, subsequently seeming difficult or impossible to ignore. This type of anxiety can be crippling to the affected and may lead to avoidant behavior. Those who experience this phenomenon may feel concern over the cause of their derealization. It is often difficult to accept that such a disturbing symptom is simply a result of anxiety, and the individual may often think that the cause must be something more serious. This can, in turn, cause more anxiety and worsen the derealization. Derealization also affects the learning process. Because the individual almost sees the events as if in 3rd person, they cannot properly process information.
People suffering from derealization have described feeling as if the world external to them were something in a TV show or movie, or as if they were viewing it through a TV screen. This, and other similar feelings attendant to derealization, can cause a sensation of alienation and distance between the person suffering from derealization and others around them.
Derealization can accompany the neurological conditions of epilepsy (particularly temporal lobe epilepsy), migraine, and mild head injury. There is a similarity between visual hypo-emotionality, a reduced emotional response to viewed objects, and derealization. This suggests a disruption of the process by which perception becomes emotionally coloured. This qualitative change in the experiencing of perception may lead to reports of anything viewed being unreal or detached.
Derealization can also manifest as an indirect result of certain vestibular disorders such as labyrinthitis and vestibular neuronitis. This is thought to result from the experience of anxiety precipitated by the functional disparity that arises between the ability to reconcile external stimuli relative to motion and equilibrioception that are compromised by vestibular dysfunction with the internal perceptions and expectations regarding the physical environment. An alternative explanation holds that a possible effect of vestibular dysfunction includes responses in the form of the modulation of noradrenergic and serotonergic activity due to a misattribution of vestibular symptoms to the presence of imminent physical danger resulting in the experience of anxiety or panic, which subsequently generate feelings of derealization.
Cannabis, psychedelics, dissociatives, antidepressants, caffeine, nitrous oxide, albuterol, and nicotine can all produce feelings resembling derealization, particularly when taken in excess. It can also result from alcohol withdrawal or benzodiazepine withdrawal.
Derealization can also be a symptom of severe sleep disorders, and mental disorders like depersonalization disorder, borderline personality disorder, bipolar disorder, schizophrenia, dissociative identity disorder, and anxiety disorders.