DLB is dementia that occurs with "some combination of fluctuating cognition, recurrent visual hallucinations, rapid eye movement (REM) sleep behavior disorder (RBD), and<unk> ", according to Armstrong (2019), when Parkinson's disease is not well established before the dementia occurs. DLB has widely varying symptoms and is more complex than many other dementias. Several areas of the nervous system (such as the autonomic nervous system and numerous regions of the brain) can be affected by Lewy pathology, in which the alpha-synuclein deposits cause damage and corresponding neurologic deficits. In DLB, there is an identifiable set of early signs and symptoms; these are called the prodromal, or pre-dementia, phase of the disease. These early signs and symptoms can appear 15 years or more before dementia develops. The earliest symptoms are constipation and dizziness from autonomic dysfunction, hyposmia (reduced ability to smell), RBD, anxiety, and depression. RBD may appear years or decades before other symptoms. Memory loss is not always an early symptom. Manifestations of DLB can be divided into essential, core, and supportive features. Dementia is the essential feature and must be present for diagnosis, while core and supportive features are further evidence in support of diagnosis (see diagnostic criteria below). Essential feature A dementia diagnosis is made after cognitive decline progresses to a point of interfering with normal daily activities, or social or occupational function. While dementia is an essential feature of DLB, it does not always appear early on, and is more likely to present as the condition progresses. Core features While specific symptoms may vary, the core features of DLB are fluctuating cognition, alertness or attention; REM sleep behavior disorder; one or more of the cardinal features of<unk> , not due to medication or stroke; and repeated visual hallucinations. The 2017 Fourth Consensus Report of the DLB Consortium determined these to be core features based on the availability of high-quality evidence indicating they are highly specific to the condition. Fluctuating cognition and alertness Fluctuations in cognitive function are the most characteristic feature of the Lewy body dementias. They are the most frequent symptom of DLB, and are often distinguishable from those of other dementias by concomitant fluctuations of attention and alertness, described by Tsamakis and Mueller (2021) as "spontaneous variations of cognitive abilities, alertness, or arousal". They are further distinguishable by a "marked amplitude between best and worst performances", according to McKeith (2002). These fluctuations vary in severity, frequency and duration; episodes last anywhere from seconds to weeks, interposed between periods of more normal functioning. When relatively lucid periods coincide with medical appointments, cognitive testing may inaccurately reflect disease severity, with subsequent assessments of cognition showing improvements from baseline. Unlike the deficits in memory and orientation that are characteristic of Alzheimer disease, the distinct impairments in cognition seen in DLB are most commonly in three domains: attention, executive function, and visuospatial function. These fluctuating impairments are present early in the course of the disease. Individuals with DLB may be easily distracted, have a hard time focusing on tasks, or appear to be "delirium-like", "zoning out", or in states of altered consciousness with spells of confusion, agitation or incoherent speech. They may have disorganized speech and their ability to organize their thoughts may change during the day. Executive function describes attentional and behavioral controls, memory and cognitive flexibility that aid problem solving and planning. Problems with executive function surface in activities requiring planning and organizing. Deficits can manifest in impaired job performance, inability to follow conversations, difficulties with multitasking, or mistakes in driving, such as misjudging distances or becoming lost. The person with DLB may experience disorders of wakefulness or sleep disorders (in addition to REM sleep behavior disorder) that can be severe. These disorders include daytime sleepiness, drowsiness or napping more than two hours a day, insomnia, periodic limb movements, restless legs syndrome and sleep apnea. REM sleep behavior disorder REM sleep behavior disorder (RBD) is a parasomnia in which individuals lose the paralysis of muscles (atonia) that is normal during rapid eye movement (REM) sleep, and consequently act out their dreams or make other abnormal movements or vocalizations. About 80% of those with DLB have RBD. Abnormal sleep behaviors may begin before cognitive decline is observed, and may appear decades before any other symptoms, often as the first clinical indication of DLB and an early sign of a synucleinopathy. On autopsy, 94 to 98% of individuals with polysomnography-confirmed RBD have a synucleinopathy—most commonly DLB or Parkinson's disease in about equal proportions. More than three out of four people with RBD are diagnosed with a neurodegenerative condition within ten years, but additional neurodegenerative diagnoses may emerge up to 50 years after RBD diagnosis. RBD may subside over time. Individuals with RBD may not be aware that they act out their dreams. RBD behaviors may include yelling, screaming, laughing, crying, unintelligible talking, nonviolent flailing, or more violent punching, kicking, choking, or scratching. The reported dream enactment behaviors are frequently violent, and involve a theme of being chased or attacked. People with RBD may fall out of bed or injure themselves or their bed partners, which may cause bruises, fractures, or subdural hematomae. Because people are more likely to remember or report violent dreams and behaviors—and to be referred to a specialist when injury occurs—recall or selection bias may explain the prevalence of violence reported in RBD.<unk> <unk>  is a clinical syndrome characterized by slowness of movement (called bradykinesia), rigidity, postural instability, and tremor; it is found in DLB and many other conditions like Parkinson's disease, Parkinson's disease dementia, and others.<unk>  occurs in more than 85% of people with DLB, who may have one or more of these cardinal features, although tremor at rest is less common. Motor symptoms may include shuffling gait, problems with balance, falls, blank expression, reduced range of facial expression, and low speech volume or a weak voice. Presentation of motor symptoms is variable, but they are usually symmetric, presenting on both sides of the body. Only one of the cardinal symptoms of<unk>  may be present, and the symptoms may be less severe than in persons with Parkinson's disease. Visual hallucinations Up to 80% of people with DLB have visual hallucinations, typically early in the course of the disease. They are recurrent and frequent; may be scenic, elaborate and detailed; and usually involve animated perceptions of animals or people, including children and family members. Examples of visual hallucinations "vary from 'little people' who casually walk around the house, 'ghosts' of dead parents who sit quietly at the bedside, to 'bicycles' that hang off of trees in the back yard". These hallucinations can sometimes provoke fear, although their content is more typically neutral. In some cases, the person with DLB has insight that the hallucinations are not real. Among those with more disrupted cognition, the hallucinations can become more complex, and they may be less aware that their hallucinations are not real. Visual misperceptions or illusions are also common in DLB but differ from visual hallucinations. While visual hallucinations occur in the absence of real stimuli, visual illusions occur when real stimuli are incorrectly perceived; for example, a person with DLB may misinterpret a floor lamp for a person. Supportive features Supportive features of DLB have less diagnostic weight, but they provide evidence for the diagnosis. Supportive features may be present early in the progression, and persist over time; they are common but they are not specific to the diagnosis. The supportive features are: * marked sensitivity to antipsychotics (neuroleptics); * marked dysautonomia (autonomic dysfunction) in which the autonomic nervous system does not work properly; * hallucinations in senses other than vision (hearing, touch, taste, and smell); * hypersomnia (excessive sleepiness); * hyposmia (reduced ability to smell); * false beliefs and delusions organized around a common theme; * postural instability, loss of consciousness, and frequent falls; * apathy, anxiety, or depression. People with DLB are very sensitive to antipsychotic medications like haloperidol, which carry an increased risk of morbidity and mortality in DLB. Partly because of loss of cells that release the neurotransmitter dopamine, people with DLB may have neuroleptic malignant syndrome, impairments in cognition or alertness, or irreversible exacerbation of<unk>  including severe rigidity, and dysautonomia from the use of antipsychotics. Dysautonomia (autonomic dysfunction) occurs when Lewy pathology affects the peripheral autonomic nervous system (the nerves dealing with the unconscious functions of organs such as the intestines, heart, and urinary tract). The first signs of autonomic dysfunction are often subtle. Manifestations include blood pressure problems such as orthostatic hypotension (significantly reduced blood pressure upon standing) and supine hypertension; constipation, urinary problems, and sexual dysfunction; loss of or reduced ability to smell; and excessive sweating, drooling, or salivation, and problems swallowing (dysphagia). Alpha-synuclein deposits can affect cardiac muscle and blood vessels. "Degeneration of the cardiac sympathetic nerves is a neuropathological feature" of the Lewy body dementias, according to Yamada Almost all people with synucleinopathies have cardiovascular dysfunction, although most are asymptomatic. Between of individuals with DLB have orthostatic hypotension due to reduced blood flow, which
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