There is more information available on this subject at Dementia on the English Wikipedia.

Dementia was a serious loss of cognitive ability in a previously unimpaired individual. Dementia occured in the Dead Space series as a term to describe the psychological effects of the influence of the various Markers. It was characterized by vivid hallucinations, violent behavior, extreme paranoia and other schizophrenic-like symptoms. It was often the result of a character's presence to a Marker signal.

Depending on the person, the symptoms are different and happened more quickly, depending on the length of the exposure to a Marker signal or the psychological state of the subject.

First, the hallucinations consisted of mostly from voices in the head or visual hallucinations such as people. Depending on the situation, the hallucinations may be calm or violent. On the Sprawl, the children are reported seeing their dead relatives as a result of the Site 12 Marker's signal. However, sometimes the subject was already in such a poor mental state that they began to immediately experience violent hallucinations (Such as Nickolas Kuttner experiencing the death of his daughter again and again after touching a fragment of the Marker 3A).

The second stage was when the subject began to experience more severe hallucinations such as Necromorphs that are not really there or other horrifying experiences and voices that attempted to make the subject hurt him/herself or others around. Sometimes, the hallucinations caused many people to commit mass suicides at once. This was usually when the subject began attacking others and possibly killing them in the process. After this action, the subject showed no signs of regret or remembered nothing.

Later in the third stage, the subject began to experience even more violent hallucinations and depending on the person varied from either visual hallucinations to noise that drove the subject mad, ending in him/her killing oneself. In Isaac's case, he started seeing violent hallucinations of Nicole that made Isaac kill himself or cloud his sense of reality. Most people ended up dead after this stage as a Necromorph outbreak began already due to the Marker signal affecting everyone around it. For unknown reasons, the signal could bring the subject in a state of coma temporarily in "Dementia Land" filled with shadowy figures and objects and sounds from the subject's past memories. The subject could also somehow "die" in these situations, possibly because they got killed by something in reality (In Isaac's case, he would shoot a Javelin spear into his head if he got too close to Nicole at the end of Dead Space 2 in "Dementia Land").

Sometimes, dementia would not cause the person to die, but rather the Marker that inflicted it would make use of the subject in order to make more Markers by imprinting the instructions in the brain. This was the case with the smartest people affected and as a result, the hallucinations usually would not be that severe and are mostly just voices or visual apparitions.

Dead SpaceEdit

In Dead Space, the protagonist, Isaac Clarke suffered from dementia throughout the game. A vision of his girlfriend, Nicole (Who was already dead, unknown to Isaac) was the most serious of Isaac's symptoms. Dr. Terrence Kyne suffered from a more serious form of this same dementia, thinking that he was in the company of his wife, Amelia despite knowing that she was dead for years. Kendra Daniels also was suffering from dementia as she mentioned to Isaac that she saw her brother (Who was not present on the Ishimura and may be dead) on a security monitor. However, this could have been a ploy to garner sympathy from Isaac in order to further manipulate him. Zach Hammond made brief mentions of headaches and he "thought that he was seeing things", but otherwise seemed sane right up until his death.

Dead Space: ExtractionEdit

In the prequel, Dead Space: Extraction, the main protagonist, Nathan McNeill began to suffer from dementia when he was not in Lexine Murdoch's presence. He saw non-existent Necromorphs and heard a woman singing "Twinkle Twinkle, Little Star."

In Chapter 1: Worlds Apart, Sam Caldwell killed several civilians, believing that they are enemies before Nathan and the other P-Sec officers arrived and gunned him down.

Dead Space (mobile)Edit

The protagonist, Vandal had a very serious form of dementia. She occasionally saw visions of herself which  transformed into a Slasher when she approached them. Sometimes, Vandal would be in one room, only to have her environment change to another, even to the extent of imagining that she was in a desert near an alien Marker. She also saw Necromorphs that are not real on numerous occasions and even believed that she was a Slasher herself at one point.

Dead Space 2Edit

In Dead Space 2, Isaac's symptoms appeared to be getting more severe and graphic. He often imagined his deceased girlfriend, Nicole as decrepit and bloody with a glow coming from her mouth and eyes. She often threatened him and on more than one occasion tried to kill him. When he was preventing her from stabbing him in the eye, Isaac soon realized that he was actually wielding the needle, showing the true severity of his illness. In the morgue of the Church of Unitology, Isaac could see multiple screaming corpses in the tubes. He also saw Necromorphs that are not real in some cases that are flashbacks of the events from the previous game, showing his occasional inability to differentiate between reality and his visions.

Dead Space 3Edit

While Isaac did not show many symptoms in the main game, his ally, John Carver did. If Dead Space 3 was played on Co-Op, Carver would experience many dementia moments revolving around the death of his wife and son. Some of the dementia moments involved him seeing his dead wife or hearing his dead son talking.

However, in Dead Space 3: Awakened, after using the Codex and falling to the ground after the battle with the Tau Volantis Moon, Isaac and Carver once again showed signs of dementia. The most notable and first that Isaac and Carver encountered a seemingly alive Norton, only to discover once they got close enough to him that Norton transformed into a Necromorph. However, it was possible that these visions are the result of the Brethren Moons' telepathic manipulations as they repeatedly demonstrated the ability to cause Isaac and Carver to have hallucinations. Another example was the final hallucination confrontation (Final boss fight) that Isaac and Carver got transported to "Dementia Land".


  • In Dead Space Mobile, when Vandal imagined herself as a Slasher, the player got to play as a Slasher for a short period of time which was the only time in the Dead Space series when the player was allowed to play as a Necromorph in the main game. Though the player could not attack or do any combat-specific actions, they could still walk and run. There are still remnants of what appeared to be a black dress on her while she was a Slasher.
  • As Isaac's Red Marker-induced dementia continued to corrupt his mind, the main menu adapted to show this through larger manifestations of the Marker pieces in Isaac's synapses as the player progressed. This was done to metaphorically show the worsening of his condition and to show that as he regained his memories, the blueprints of the Marker slowly began to resurface ( Which was why Stross awoke sooner could recall the text and the procedure to extract it earlier).
  • Though referred to as dementia both in the game and by developers, the symptoms and effects more closely resembled those of schizophrenia. The damage to the brain such as those from dementia could cause these issues in one fashion or another. However, the symptoms shown by those under the effects of Markers still shared an uncanny similarity to those of schizophrenia and not the clinical definition of dementia. However, schizophrenia typically caused auditory hallucinations and visual ones are quite rare.
  • In Dead Space 2, there was a text log entry done by a teacher talking about the children having "imaginary friends" as the log said. The kids would say that these "imaginary friends" are dead relatives. This was a result of the Marker's effect on the children's minds.
  • While hallucinations are not commonly found in dementia sufferers, delusions could mean that Isaac's diagnosis was plausible. This was because delusions (Which are a variety of hallucinations) tended to involve belief in implausible events. These could range from realistic such as the subject believing that he was under constant surveillance to unrealistic like believing that you could hear the dead (A symptom that Nolan Stross had throughout such as hearing the steps from his dead wife and son).
  • Curiously, there was no evidence that the soldiers of the S.C.A.F. detachment on Tau Volantis experienced hallucinations, despite being on a planet infested with Red Markers, although many of their forces experienced symptoms of dementia from being driven to spoil the food supply to actually devouring the Necromorph flesh. John Carver was the only person on Tau Volantis to experience both dementia and hallucinations until Isaac and Carver began experiencing them again following the destruction of Tau Volantis' Brethren Moon.