 | This article needs more medical references for verification or relies too heavily on primary sources .(April 2018) |  |
Visual hallucinations in psychosis are hallucinations accompanied by delusions. [1]
| This article needs more medical references for verification or relies too heavily on primary sources .(April 2018) | |
Visual hallucinations in psychosis are hallucinations accompanied by delusions. [1]
Visual hallucinations in psychoses are reported to have physical properties similar to real perceptions. They are often life-sized, detailed, and solid, and are projected into the external world. They typically appear anchored in external space, just beyond the reach of individuals, or further away. They can have three-dimensional shapes, with depth and shadows, and distinct edges. They can be colorful or in black and white and can be static or have movement. [2] [3] [4] [5] [6] [7] [8]
Visual hallucinations may be simple, or non-formed visual hallucinations, or complex, or formed visual hallucinations.
Simple visual hallucinations without structure are known as phosphenes and those with geometric structure are known as photopsias. [9] [10] [11] These hallucinations are caused by irritation to the primary visual cortex (Brodmann's area 17). [12]
Sometimes, hallucinations are 'Lilliputian', i.e., patients experience visual hallucinations where there are miniature people, often undertaking unusual actions. Lilliputian hallucinations may be accompanied by wonder, rather than terror. [13] [14]
The frequency of hallucinations varies widely from rare to frequent, as does duration (seconds to minutes). The content of hallucinations varies as well. Complex (formed) visual hallucinations are more common than Simple (non-formed) visual hallucinations. [5] [7] In contrast to hallucinations experienced in organic conditions, hallucinations experienced as symptoms of psychoses tend to be more frightening. An example of this would be hallucinations that have imagery of bugs, dogs, snakes, distorted faces. Visual hallucinations may also be present in those with Parkinson's, where visions of dead individuals can be present. In psychoses, this is relatively rare, although visions of God, angels, the devil, saints, and fairies are common. [6] [7] Individuals often report being surprised when hallucinations occur and are generally helpless to change or stop them. [4] In general, individuals believe that visions are experienced only by themselves. [4] [5]
Two neurotransmitters are particularly important in visual hallucinations – serotonin and acetylcholine. They are concentrated in the visual thalamic nuclei and visual cortex. [13]
The similarity of visual hallucinations that stem from diverse conditions suggest a common pathway for visual hallucinations. Three pathophysiologic mechanisms are thought to explain this.
The first mechanism has to do with cortical centers responsible for visual processing. Irritation of visual association cortices (Brodmann's areas 18 and 19) cause complex visual hallucinations. [12] [15]
The second mechanism is deafferentation, the interruption or destruction of the afferent connections of nerve cells, of the visual system, caused by lesions, leading to the removal of normal inhibitory processes on cortical input to visual association areas, leading to complex hallucinations as a release phenomenon. [14] [15]
[9] The DSM-V lists visual hallucinations as a primary diagnostic criterion for several psychotic disorders, including schizophrenia and schizoaffective disorder. [1] [10] [16] Visual hallucinations can occur as a symptom of the above psychotic disorders in 24% to 72% of patients at some point in the course of their illness. [2] [17] [11]
Catatonia is a complex neuropsychiatric behavioral syndrome that is characterized by abnormal movements, immobility, abnormal behaviors, and withdrawal. The onset of catatonia can be acute or subtle and symptoms can wax, wane, or change during episodes. There are several subtypes of catatonia: akinetic catatonia, excited catatonia, malignant catatonia, delirious mania, and self-injurious behaviors in autism.
Psychosis is an abnormal condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior that is inappropriate for a given situation. There may also be sleep problems, social withdrawal, lack of motivation, and difficulties carrying out daily activities. Psychosis can have serious adverse outcomes.
Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations, delusions, and disorganized thinking. Other symptoms include social withdrawal, decreased emotional expression, and apathy. Symptoms typically develop gradually, begin during young adulthood, and in many cases never become resolved. There is no objective diagnostic test; diagnosis is based on observed behavior, a history that includes the person's reported experiences, and reports of others familiar with the person. To be diagnosed with schizophrenia, symptoms and functional impairment need to be present for six months (DSM-5) or one month (ICD-11). Many people with schizophrenia have other mental disorders, especially substance use disorders, depressive disorders, anxiety disorders, and obsessive–compulsive disorder.
A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combination of 2 conscious states of brain wakefulness and REM sleep. They are distinguishable from several related phenomena, such as dreaming, which does not involve wakefulness; pseudohallucination, which does not mimic real perception, and is accurately perceived as unreal; illusion, which involves distorted or misinterpreted real perception; and mental imagery, which does not mimic real perception, and is under voluntary control. Hallucinations also differ from "delusional perceptions", in which a correctly sensed and interpreted stimulus is given some additional significance. Many hallucinations happen also during sleep paralyses.
Schizoaffective disorder is a mental disorder characterized by abnormal thought processes and an unstable mood. This diagnosis is made when the person has symptoms of both schizophrenia and a mood disorder: either bipolar disorder or depression. The main criterion for a diagnosis of schizoaffective disorder is the presence of psychotic symptoms for at least two weeks without any mood symptoms present. Schizoaffective disorder can often be misdiagnosed when the correct diagnosis may be psychotic depression, bipolar I disorder, schizophreniform disorder, or schizophrenia. It is imperative for providers to accurately diagnose patients, as treatment and prognosis differ greatly for each of these diagnoses.
Delusional disorder is a mental illness in which a person has delusions, but with no accompanying prominent hallucinations, thought disorder, mood disorder, or significant flattening of affect. Delusions are a specific symptom of psychosis. Delusions can be bizarre or non-bizarre in content; non-bizarre delusions are fixed false beliefs that involve situations that could occur in real life, such as being harmed or poisoned. Apart from their delusion or delusions, people with delusional disorder may continue to socialize and function in a normal manner and their behavior does not necessarily generally seem odd. However, the preoccupation with delusional ideas can be disruptive to their overall lives.
A thought disorder (TD) is any disturbance in cognition that adversely affects language and thought content, and thereby communication. A variety of thought disorders were said to be characteristic of people with schizophrenia. A content-thought disorder is typically characterized by the experience of multiple delusional fragments. The term thought disorder is often used to refer to a formal thought disorder.
The mental status examination (MSE) is an important part of the clinical assessment process in neurological and psychiatric practice. It is a structured way of observing and describing a patient's psychological functioning at a given point in time, under the domains of appearance, attitude, behavior, mood and affect, speech, thought process, thought content, perception, cognition, insight, and judgment. There are some minor variations in the subdivision of the MSE and the sequence and names of MSE domains.
Hallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after a previous use of psychedelics, THC, or SSRIs. The hallucinations and perceptual changes consist of but are not limited to visual snow, trails and after images (palinopsia), light fractals on flat surfaces, intensified colors, altered motion perception, pareidolia, micropsia, and macropsia. People who have never previously taken drugs have also reported some visual anomalies associated with HPPD.
Psychotic depression, also known as depressive psychosis, is a major depressive episode that is accompanied by psychotic symptoms. It can occur in the context of bipolar disorder or major depressive disorder. It can be difficult to distinguish from schizoaffective disorder, a diagnosis that requires the presence of psychotic symptoms for at least two weeks without any mood symptoms present. Unipolar psychotic depression requires that the psychotic features occur only during episodes of major depression. Diagnosis using the DSM-5 involves meeting the criteria for a major depressive episode, along with the criteria for "mood-congruent or mood-incongruent psychotic features" specifier.
Paraphrenia is a mental disorder characterized by an organized system of paranoid delusions with or without hallucinations and without deterioration of intellect or personality.
Oneiroid syndrome (OS) is a condition involving dream-like disturbances of one's consciousness by vivid scenic hallucinations, accompanied by catatonic symptoms, delusions, or psychopathological experiences of a kaleidoscopic nature. The term is from Ancient Greek "ὄνειρος" and "εἶδος". It is a common complication of catatonic schizophrenia, although it can also be caused by other mental disorders. The dream-like experiences are vivid enough to seem real to the patient. OS is distinguished from delirium by the fact that the imaginative experiences of patients always have an internal projection. This syndrome is hardly mentioned in standard psychiatric textbooks, possibly because it is not listed in DSM.
An auditory hallucination, or paracusia, is a form of hallucination that involves perceiving sounds without auditory stimulus. While experiencing an auditory hallucination, the affected person would hear a sound or sounds which did not come from the natural environment.
Risk factors of schizophrenia include many genetic and environmental phenomena. The prevailing model of schizophrenia is that of a special neurodevelopmental disorder with no precise boundary or single cause. Schizophrenia is thought to develop from very complex gene–environment interactions with vulnerability factors. The interactions of these risk factors are intricate, as numerous and diverse medical insults from conception to adulthood can be involved. The combination of genetic and environmental factors leads to deficits in the neural circuits that affect sensory input and cognitive functions. Historically, this theory has been broadly accepted but impossible to prove given ethical limitations. The first definitive proof that schizophrenia arises from multiple biological changes in the brain was recently established in human tissue grown from patient stem cells, where the complexity of disease was found to be "even more complex than currently accepted" due to cell-by-cell encoding of schizophrenia-related neuropathology.
Grandiose delusions (GD), also known as delusions of grandeur or expansive delusions, are a subtype of delusion that occur in patients with a wide range of psychiatric diseases, including two-thirds of patients in manic state of bipolar disorder, half of those with schizophrenia, patients with the grandiose subtype of delusional disorder, frequently in narcissistic personality disorder, and a substantial portion of those with substance abuse disorders. GDs are characterized by fantastical beliefs that one is famous, omnipotent, wealthy, or otherwise very powerful. The delusions are generally fantastic and typically have a religious, science fictional, or supernatural theme. There is a relative lack of research into GD, in contrast to persecutory delusions and auditory hallucinations. Around 10% of healthy people experience grandiose thoughts at some point in their lives but do not meet full criteria for a diagnosis of GD.
Lesions in the visual pathway affect vision most often by creating deficits or negative phenomena, such as blindness, visual field deficits or scotomas, decreased visual acuity and color blindness. On occasion, they may also create false visual images, called positive visual phenomena. These images can be a result of distortion of incoming sensory information leading to an incorrect perception of a real image called an illusion. When the visual system produces images which are not based on sensory input, they can be referred to as hallucinations. The visual phenomena may last from brief moments to several hours, but they also can be permanent. They are generally associated with other symptoms but occasionally are isolated. Conditions causing these phenomena include disruptions in the visual input along the pathways lesions in the extracortical visual system, migraines, seizures, toxic-metabolic encephalopathy, psychiatric conditions and sleep apnea, among others. The mechanisms underlying positive visual phenomena are not yet well understood. Possible mechanisms may be: 1) defect in the sensory input causing compensatory upregulation of the visual cortex, 2) faulty visual processing in which inputs are normal but lesions result in an inappropriate pattern of cortical excitation, 3)variants of normal visual processing. Of all forms of hallucination, visual hallucinations are the least likely to be associated with psychiatric disorders. For example most patients with visual hallucinations do not have schizophrenia and most patients with schizophrenia do not have visual hallucinations.
Substance-induced psychosis is a form of psychosis that is attributed to substance use. It is a psychosis that results from the effects of chemicals or drugs, including those produced by the body itself. Various psychoactive substances have been implicated in causing or worsening psychosis in users.
Childhood schizophrenia is similar in characteristics of schizophrenia that develops at a later age, but has an onset before the age of 13 years, and is more difficult to diagnose. Schizophrenia is characterized by positive symptoms that can include hallucinations, delusions, and disorganized speech; negative symptoms, such as blunted affect and avolition and apathy, and a number of cognitive impairments. Differential diagnosis is problematic since several other neurodevelopmental disorders, including autism spectrum disorder, language disorder, and attention deficit hyperactivity disorder, also have signs and symptoms similar to childhood-onset schizophrenia.
The diagnosis of schizophrenia, a psychotic disorder, is based on criteria in either the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, or the World Health Organization's International Classification of Diseases (ICD). Clinical assessment of schizophrenia is carried out by a mental health professional based on observed behavior, reported experiences, and reports of others familiar with the person. Diagnosis is usually made by a psychiatrist. Associated symptoms occur along a continuum in the population and must reach a certain severity and level of impairment before a diagnosis is made. Schizophrenia has a prevalence rate of 0.3-0.7% in the United States
Bouffée délirante (BD) is an acute and transient psychotic disorder. It is a uniquely French psychiatric diagnostic term with a long history in France and various French speaking nations: Caribbean, e.g. Haiti, Guadeloupe, Antilles and Francophone Africa. The term BD was originally coined and described by Valentin Magnan (1835–1916), fell into relative disuse and was later revived by Henri Ey (1900–1977).