Clouding of consciousness, also called brain fog or mental fog, [1] [2] occurs when a person is slightly less wakeful or aware than normal. [3] They are less aware of time and their surroundings, and find it difficult to pay attention. [3] People describe this subjective sensation as their mind being "foggy". [4]
The term clouding of consciousness has always denoted the main pathogenetic feature of delirium since physician Georg Greiner [5] pioneered the term (Verdunkelung des Bewusstseins) in 1817. [6] The Diagnostic and Statistical Manual of Mental Disorders (DSM) has historically used the term in its definition of delirium. [7] The DSM-III-R and the DSM-IV replaced "clouding of consciousness" with "disturbance of consciousness" to make it easier to operationalize, but it is still fundamentally the same thing. [8] Clouding of consciousness may be less severe than delirium on a spectrum of abnormal consciousness. [3] [9] [10] Clouding of consciousness may be synonymous with subsyndromal delirium. [11]
Subsyndromal delirium differs from normal delirium by being overall less severe, lacking acuteness in onset and duration, having a relatively stable sleep-wake cycle, and having relatively stable motor alterations. [12] Subsyndromal delirium's significant clinical features are inattention, thought process abnormalities, comprehension abnormalities, and language abnormalities. [12] Delirium's full clinical manifestations may never be reached. [11] Among intensive care unit patients, subsyndromal subjects were as likely to survive as patients with a Delirium Screening Checklist score of 0, but required extended care at rates greater than 0-scoring patients (although lower rates than those with full delirium) [11] or have a decreased post-discharge level of functional independence vs. the general population but still more independence than full delirium. [12]
In clinical practice, no standard test is exclusive and specific; therefore, the diagnosis depends on the physician's subjective impression. The DSM-IV-TR instructs clinicians to code subsyndromal delirium presentations under the miscellaneous category "cognitive disorder not otherwise specified". [13]
The conceptual model of clouding of consciousness is that of a part of the brain regulating the "overall level" of consciousness, which is responsible for awareness of oneself and of the environment. [3] [14] Various etiologies disturb this regulating part of the brain, which in turn disturbs the "overall level" of consciousness. [15] This system of a sort of general activation of consciousness is called "arousal" or "wakefulness". [14]
It is not necessarily accompanied by drowsiness. [16] Patients may be awake (not sleepy) yet still have a clouded consciousness (disorder of wakefulness). [17] Paradoxically, affected individuals say that they are "awake but, in another way, not". [18] Lipowski points out that decreased "wakefulness" as used here is not exactly synonymous with drowsiness. One is a stage on the way to coma, the other on the way to sleep, which is very different. [19] [20]
The affected person has a sensation of mental clouding described in the patient's own words as "foggy". [4] One patient said, "I thought it became like misty, in some way... the outlines were sort of fuzzy". [18] Others may describe a "spaced-out" feeling. [21] Affected people compare their overall experience to that of a dream, because, as in a dream, consciousness, attention, orientation to time and place, perceptions, and awareness are disturbed. [22] Barbara Schildkrout, a clinical instructor in psychiatry at the Harvard Medical School, described her subjective experience of clouding of consciousness, which she also called "mental fog", after taking a single dose of chlorpheniramine (an antihistamine for her allergy to cottonwood) on a cross-country road trip. She described feeling "out of it" and being in a "dreamy state". She described a sense of not trusting her own judgment and a dulled awareness, not knowing how much time had passed. [1] Clouding of consciousness is not the same thing as depersonalization , though people affected by both compare their experience to that of a dream. Psychometric tests produce little evidence of a relationship between clouding of consciousness and depersonalization. [23]
Brain fog may affect performance on virtually any cognitive task. [1] As one author put it, "It should be apparent that cognition is not possible without a reasonable degree of arousal." [3] Cognition includes perception, memory, learning, executive functions, language, constructive abilities, voluntary motor control, attention, and mental speed. Brain fog's most significant clinical features are inattention, thought process abnormalities, comprehension abnormalities, and language abnormalities. [12] The extent of the impairment is variable because inattention may impair several cognitive functions. Affected people may complain of forgetfulness, being "confused", [24] or being "unable to think straight". [24] Despite the similarities, subsyndromal delirium is not the same thing as mild cognitive impairment ; the fundamental difference is that mild cognitive impairment is a dementia-like impairment, which does not involve a disturbance in arousal (wakefulness). [25]
The term "brain fog" is used to represent a subjective condition of perceived cognitive impairment. It is defined as "a phenomenon of fluctuating states of perceived cognitive dysfunction that could have implications in the functional application of cognitive skills in people's participation in daily activities". [26] Brain fog is a common symptom in many illnesses where chronic pain is a major component. [26] Brain fog affects 15% to 40% of those with chronic pain as their major illness. [27] In such illnesses, pain processing may use up resources, decreasing the brain's ability to think effectively. [26]
Many people with fibromyalgia experience cognitive problems [28] (known as "fibrofog" or "brainfog"), which may involve impaired concentration, [29] [30] [ unreliable medical source? ] [31] problems with short [32] - and long-term memory, short-term memory consolidation, [32] working memory, [33] impaired speed of performance, [32] inability to multitask, cognitive overload, [32] and diminished attention span. About 75% of fibromyalgia patients report significant problems with concentration, memory, and multitasking. [34] A 2018 meta-analysis found that the largest differences between fibromyalgia patients and healthy subjects were for inhibitory control, memory, and processing speed. [34] Many of these are also common symptoms of ADHD (attention deficit hyperactivity disorder), and studies have linked the two conditions, to the point that a fibromyalgia diagnosis has been proposed as an indication to screen for ADHD. [35] [36] [37] It is alternatively hypothesized that the increased pain compromises attention systems, resulting in cognitive problems. [34]
In chronic fatigue syndrome, also known as myalgic encephalomyelitis, the CDC's recommended criteria for diagnosis [38] include that one of the following symptoms must be present: [38]
Lyme disease's neurologic syndrome, called Lyme encephalopathy, is associated with subtle memory and cognitive difficulties, among other issues. [39] Lyme can cause a chronic encephalomyelitis that resembles multiple sclerosis. It may be progressive and can involve cognitive impairment, migraines, balance problems, and other symptoms.[ citation needed ]
Brain fog is a common symptom of hypothyroidism, with a survey showing that 79.2% of those with the condition reported experiencing brain fog to some extent, either selecting the option for "frequently" or "all the time". [40] While it is unclear how the disease leads to brain fog, proper treatment with levothyroxine has been shown to reduce cognitive impairment. [41]
The emerging concept of sluggish cognitive tempo has also been implicated in the expression of brain fog symptoms. [42]
Patients recovering from COVID-19 report experiencing brain fog, which can reflect a wide variety of neurological and psychological symptoms linked to COVID-19. [43]
Brain fog and other neurological symptoms may also result from mold exposure. [44] [45] [46] [47] [48] This may be due to mycotoxin exposure and consequent innate immune system activation and inflammation, including in the central nervous system. [49] [44] [45] [46] [47] [48] But adverse neurological health effects of mold exposure are controversial due to inadequate research and data, and more research is needed in this area. [49] [50] [51] [44] [46] [48]
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. It has historically been related to schizophrenia, but catatonia is most often seen in mood disorders. It is now known that catatonic symptoms are nonspecific and may be observed in other mental, neurological, and medical conditions. Catatonia is now a stand-alone diagnosis, and the term is used to describe a feature of the underlying disorder.
Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform everyday activities. This typically involves problems with memory, thinking, behavior, and motor control. Aside from memory impairment and a disruption in thought patterns, the most common symptoms of dementia include emotional problems, difficulties with language, and decreased motivation. The symptoms may be described as occurring in a continuum over several stages. Dementia ultimately has a significant effect on the individual, their caregivers, and their social relationships in general. A diagnosis of dementia requires the observation of a change from a person's usual mental functioning and a greater cognitive decline than might be caused by the normal aging process.
Delirium is a specific state of acute confusion attributable to the direct physiological consequence of a medical condition, effects of a psychoactive substance, or multiple causes, which usually develops over the course of hours to days. As a syndrome, delirium presents with disturbances in attention, awareness, and higher-order cognition. People with delirium may experience other neuropsychiatric disturbances, including changes in psychomotor activity, disrupted sleep-wake cycle, emotional disturbances, disturbances of consciousness, or, altered state of consciousness, as well as perceptual disturbances, although these features are not required for diagnosis.
Fibromyalgia is a medical syndrome which causes chronic widespread pain, accompanied by fatigue, waking unrefreshed, and cognitive symptoms. Other symptoms can include headaches, lower abdominal pain or cramps, and depression. People with fibromyalgia can also experience insomnia and a general hypersensitivity. The cause of fibromyalgia is unknown, but is believed to involve a combination of genetic and environmental factors. Environmental factors may include psychological stress, trauma, and certain infections. Since the pain appears to result from processes in the central nervous system, the condition is referred to as a "central sensitization syndrome".
Hypersomnia is a neurological disorder of excessive time spent sleeping or excessive sleepiness. It can have many possible causes and can cause distress and problems with functioning. In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), hypersomnolence, of which there are several subtypes, appears under sleep-wake disorders.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder that begins in early childhood, persists throughout adulthood, and affects two crucial areas of development: social communication and restricted, repetitive patterns of behavior. There are many conditions comorbid to autism spectrum disorder such as attention-deficit hyperactivity disorder and epilepsy.
Ganser syndrome is a rare dissociative disorder characterized by nonsensical or wrong answers to questions and other dissociative symptoms such as fugue, amnesia or conversion disorder, often with visual pseudohallucinations and a decreased state of consciousness. The syndrome has also been called nonsense syndrome, balderdash syndrome, syndrome of approximate answers, hysterical pseudodementia or prison psychosis.
Cognitive disorders (CDs), also known as neurocognitive disorders (NCDs), are a category of mental health disorders that primarily affect cognitive abilities including learning, memory, perception, and problem-solving. Neurocognitive disorders include delirium, mild neurocognitive disorders, and major neurocognitive disorder. They are defined by deficits in cognitive ability that are acquired, typically represent decline, and may have an underlying brain pathology. The DSM-5 defines six key domains of cognitive function: executive function, learning and memory, perceptual-motor function, language, complex attention, and social cognition.
Cognitive disengagement syndrome (CDS) is an attention syndrome characterised by prominent dreaminess, mental fogginess, hypoactivity, sluggishness, slow reaction time, staring frequently, inconsistent alertness, and a slow working speed. To scientists in the field, it has reached the threshold of evidence and recognition as a distinct syndrome.
Post-concussion syndrome (PCS), also known as persisting symptoms after concussion, is a set of symptoms that may continue for weeks, months, or years after a concussion. PCS is medically classified as a mild traumatic brain injury (TBI). About 35% of people with concussion experience persistent or prolonged symptoms 3 to 6 months after injury. Prolonged concussion is defined as having concussion symptoms for over four weeks following the first accident in youth and for weeks or months in adults.
Frontal lobe disorder, also frontal lobe syndrome, is an impairment of the frontal lobe of the brain due to disease or frontal lobe injury. The frontal lobe plays a key role in executive functions such as motivation, planning, social behaviour, and speech production. Frontal lobe syndrome can be caused by a range of conditions including head trauma, tumours, neurodegenerative diseases, neurodevelopmental disorders, neurosurgery and cerebrovascular disease. Frontal lobe impairment can be detected by recognition of typical signs and symptoms, use of simple screening tests, and specialist neurological testing.
Organic brain syndrome, also known as organic brain disease, organic brain damage, organic brain disorder, organic mental syndrome, or organic mental disorder, refers to any syndrome or disorder of mental function whose cause is alleged to be known as organic (physiologic) rather than purely of the mind. These names are older and nearly obsolete general terms from psychiatry, referring to many physical disorders that cause impaired mental function. They are meant to exclude psychiatric disorders. Originally, the term was created to distinguish physical causes of mental impairment from psychiatric disorders, but during the era when this distinction was drawn, not enough was known about brain science for this cause-based classification to be more than educated guesswork labeled with misplaced certainty, which is why it has been deemphasized in current medicine. While mental or behavioural abnormalities related to the dysfunction can be permanent, treating the disease early may prevent permanent damage in addition to fully restoring mental functions. An organic cause to brain dysfunction is suspected when there is no indication of a clearly defined psychiatric or "inorganic" cause, such as a mood disorder.
Medically unexplained physical symptoms are symptoms for which a treating physician or other healthcare providers have found no medical cause, or whose cause remains contested. In its strictest sense, the term simply means that the cause for the symptoms is unknown or disputed—there is no scientific consensus. Not all medically unexplained symptoms are influenced by identifiable psychological factors. However, in practice, most physicians and authors who use the term consider that the symptoms most likely arise from psychological causes. Typically, the possibility that MUPS are caused by prescription drugs or other drugs is ignored. It is estimated that between 15% and 30% of all primary care consultations are for medically unexplained symptoms. A large Canadian community survey revealed that the most common medically unexplained symptoms are musculoskeletal pain, ear, nose, and throat symptoms, abdominal pain and gastrointestinal symptoms, fatigue, and dizziness. The term MUPS can also be used to refer to syndromes whose etiology remains contested, including chronic fatigue syndrome, fibromyalgia, multiple chemical sensitivity and Gulf War illness.
Oneiroid syndrome (OS) is a condition involving dream-like disturbances of one's consciousness by vivid scenic hallucinations, accompanied by catatonic symptoms (either catatonic stupor or excitement), delusions, or psychopathological experiences of a kaleidoscopic nature. The term is from Ancient Greek "ὄνειρος" (óneiros, meaning "dream") and "εἶδος" (eîdos, meaning "form, likeness"; literally dream-like / oneiric or oniric, sometimes called "nightmare-like"). 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.
Pseudodementia is a condition where mental cognition can be temporarily decreased. The term pseudodementia is applied to the range of functional psychiatric conditions such as depression, schizophrenia and other psychosis, mania, dissociative disorder and conversion disorder that may mimic organic dementia, but are essentially reversible on treatment. Pseudodementia typically involves three cognitive components: memory issues, deficits in executive functioning, and deficits in speech and language. Specific cognitive symptoms might include trouble recalling words or remembering things in general, decreased attentional control and concentration, difficulty completing tasks or making decisions, decreased speed and fluency of speech, and impaired processing speed. People with pseudodementia are typically very distressed about the cognitive impairment they experience. Two treatments found to be effective for the treatment of depression may also be beneficial in the treatment of pseudodementia: Cognitive behavioral therapy (CBT) which identifies behaviors that positively and negatively impact mood, and Interpersonal therapy which focuses on identifying ways in which interpersonal relationships contribute to depression.
Alcohol withdrawal syndrome (AWS) is a set of symptoms that can occur following a reduction in alcohol use after a period of excessive use. Symptoms typically include anxiety, shakiness, sweating, vomiting, fast heart rate, and a mild fever. More severe symptoms may include seizures, and delirium tremens (DTs); which can be fatal in untreated patients. Symptoms start at around 6 hours after last drink. Peak incidence of seizures occurs at 24-36 hours and peak incidence of delirium tremens is at 48-72 hours.
A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weakness, poor coordination, loss of sensation, seizures, confusion, pain, tauopathies, and altered levels of consciousness. There are many recognized neurological disorders, some are relatively common, but many are rare.
Functional disorders are a group of recognisable medical conditions which are due to changes to the functioning of the systems of the body rather than due to a disease affecting the structure of the body.
Somatic symptom disorder, also known as somatoform disorder, or somatization disorder, is defined by one or more chronic physical symptoms that coincide with excessive and maladaptive thoughts, emotions, and behaviors connected to those symptoms. The symptoms are not deliberately produced or feigned, and they may or may not coexist with a known medical ailment.
The term functional somatic syndrome (FSS) refers to a group of chronic diagnoses with no identifiable organic cause. This term was coined by Hemanth Samkumar. It encompasses disorders such as fibromyalgia, chronic widespread pain, temporomandibular disorder, irritable bowel syndrome, lower back pain, tension headache, atypical face pain, non-cardiac chest pain, insomnia, palpitation, dyspepsia and dizziness. General overlap exists between this term, somatization and somatoform. The status of ME/CFS as a functional somatic syndrome is contested. Although the aetiology remains unclear, there are consistent findings of biological abnormalities, and major health bodies such as the NAM, WHO, and NIH, classify it as an organic disease.