Early onset dementia or young onset dementia refers to dementia with symptom onset prior to age 65. This condition is a significant public health concern, as the number of individuals with early onset dementia is increasing worldwide. [1]
Early onset dementia or young onset dementia refers to dementia with symptom onset prior to age 65. This condition is a significant public health concern, as the number of individuals with early onset dementia is increasing worldwide. [1]
Early onset dementia is a general term that describes a group of conditions featuring progressive cognitive decline, particularly in the domains of executive function, learning, language, memory, or behavior. This condition may occur due to various different causes, including degenerative, autoimmune, or infectious processes. The most common form of early onset dementia is Alzheimer's disease, followed by frontotemporal dementia, and vascular dementia, with Alzheimer's disease accounting for between 40 and 50% of cases. [2] [3] Less common forms of early onset dementia include Lewy body dementias (dementia with Lewy bodies and Parkinson's disease dementia), Huntington's disease, Creutzfeldt–Jakob disease, multiple sclerosis, alcohol-induced dementia, and other conditions.
The term young onset dementia is becoming more widely used to avoid the potential confusion between early onset dementia and early stage dementia This term is now used as presenile dementia which is a historical term of people diagnosed with dementia from a younger age of 51 years old. This is caused by a atypical arterioclerosis of the brain. Although these terms can be exchanged during the course of literature it can cause misunderstandings between the subgroups of a younger crowd living with dementia. Additionally terminology recent resaerch has focussed on the differnt age groups of dementia and how they differ from one another. Studies have found there is a greater diversity within younger people who have dementia compared to older patients. Evidence have been found on Alzheimer's disease causes in the brains of young people which can result in phenotypic variants compared to older people. Which explains why younger people with Alzheimer's disease have more awareness than older individuals. [4] . [5]
Early onset dementia is less common than late onset dementia, the former accounting for approximately 10% of dementias globally. [3] Recent studies estimate the prevalence of early onset dementia to be approximately 3.55 million people aged 30–64 worldwide, and will triple by 2050. [6] with an incidence of 119 per 100,000 individuals. [1] Additionally, there is approximately a 1:1 ratio in prevalence of Early onset dementia between males and females, with no significant difference between ethnic groups in gender distribution pattern. [7] [8] Similar to late onset dementia, the prevalence of early onset dementia increases exponentially with age, doubling every five years of age. [7] The continuous increase in prevalence with age seen in Alzheimer's and frontotemporal dementia versions of early onset dementia is disproportionally led by the most common variant of each cause, namely amnestic Alzheimer's and behavioral variant of frontotemporal dementia. [9]
Traditional risk factors for the development of late onset dementia, such as diabetes mellitus, hypertension, and obesity, have also been identified as risk factors for early onset dementia. Several other chronic conditions have recently been identified that are also associated with the development of early onset dementia, including cardiovascular, respiratory, or gastrointestinal disease. [10] The presence of one or multiple of these chronic conditions is more predictive of early onset dementia compared to late onset dementia. [10] Furthermore, the association between low socioeconomic status and the development of dementia is also more pronounced in early onset dementia compared to late onset dementia. [11] Additionally, depending on the etiology of early onset dementia, family history may be a significant risk factor, especially for Alzheimer's early onset dementia. [8] Additionally it is more common for women to be diagnosed with Alzheimer's disease compared to men, for men it is more common to conduct vascular dementia. Studies have shown men will less likely develop Alzheimer's disease. [12]
Though widely accepted, the definition of early onset dementia as less than 65 years of age continues to be an artificial cut-off based on the traditional retirement age in most countries. [13] Nevertheless, the purpose of having a specific age cut-off is evidenced in the significant differences in the etiology and prognosis of dementia depending on the age category of the patient. Furthermore, the diagnosis of early onset dementia continues to be challenging due to the wide range of symptoms at presentation and increased likelihood of not considering neurodegenerative causes in this population. Recent studies indicate an average of 4.4 years time to diagnosis for early onset dementia, compared to 2.8 years for late onset dementia. [7] Indications for the work-up of early onset dementia in this patient population include progressive, unexplained neurological symptoms; new-onset behavioral changes inconsistent with previous personality, especially in patients without significant psychiatric history; or cognitive changes in patients with significant family history of early onset dementia. [14] The diagnostic work-up of early onset dementia includes combinations of detailed history taking, neuroimaging, behavioral testing, and genetic testing. [14] Special considerations for interdisciplinary support should be pursued for younger patients, such as behavioral counseling, social services, or home modifications. The World Health Organization promotes the importance of rehabilitation services (including cognitive, psychological, physical and social support) to improve the quality of life of those with dementia. [15] Despite this specific services for those with early onset dementia are rare. [16] The integration of age-appropriate services into existing dementia care, and the use of telehealth have both been explored as options for reducing cognitive disability, and improving quality of life, in early onset dementia. [16]
Compared to late onset dementia, patients with early onset dementia are more likely to have dementias other than Alzheimer's disease, although Alzheimer's is the most common etiology in either case. [13] In general, early onset dementia has a faster progression and features more extensive neurological damage when compared to late onset dementia. It is hypothesized that this may be due to decreased cognitive reserve seen in late onset dementias, causing more significant complications relative to pathological damage. [13] Furthermore, studies have shown differences in the areas of cognition that are likely to be affected when comparing early onset to late onset dementia. In terms of behavioral symptoms, early onset dementia is more likely to affect attention, but less likely to cause confusion, delusions, hallucinations, agitation, or disinhibition. In terms of motor symptoms, early onset dementia is less likely to affect verbal fluency and motor executive function compared to late onset dementia. [13]
Estimation of survival rate in early onset dementias is a component patient prognosis, management, and treatment. In general, a better prognosis is positively correlated with earlier age of onset. [13] Average survival time is approximately 6–10 years following diagnosis for both men and women, with variability depending on specific type of dementia. [7] The most common cause of immediate death in early onset dementia is respiratory disease (e.g. pneumonia); other causes include cardiovascular events and cerebrovascular disease. [13]
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.
Dementia with Lewy bodies (DLB) is a type of dementia characterized by changes in sleep, behavior, cognition, movement, and regulation of automatic bodily functions. Memory loss is not always an early symptom. The disease worsens over time and is usually diagnosed when cognitive impairment interferes with normal daily functioning. Together with Parkinson's disease dementia, DLB is one of the two Lewy body dementias. It is a common form of dementia, but the prevalence is not known accurately and many diagnoses are missed. The disease was first described on autopsy by Kenji Kosaka in 1976, and he named the condition several years later.
Vascular dementia is dementia caused by a series of strokes. Restricted blood flow due to strokes reduces oxygen and glucose delivery to the brain, causing cell injury and neurological deficits in the affected region. Subtypes of vascular dementia include subcortical vascular dementia, multi-infarct dementia, stroke-related dementia, and mixed dementia.
Rapid eye movement sleep behavior disorder or REM sleep behavior disorder (RBD) is a sleep disorder in which people act out their dreams. It involves abnormal behavior during the sleep phase with rapid eye movement (REM) sleep. The major feature of RBD is loss of muscle atonia during otherwise intact REM sleep. The loss of motor inhibition leads to sleep behaviors ranging from simple limb twitches to more complex integrated movements that can be violent or result in injury to either the individual or their bedmates.
Frontotemporal dementia (FTD), also called frontotemporal degeneration disease or frontotemporal neurocognitive disorder, encompasses several types of dementia involving the progressive degeneration of the brain's frontal and temporal lobes. Men and women appear to be equally affected. FTD generally presents as a behavioral or language disorder with gradual onset. Signs and symptoms tend to appear in late adulthood, typically between the ages of 45 and 65, although it can affect people younger or older than this. Currently, no cure or approved symptomatic treatment for FTD exists, although some off-label drugs and behavioral methods are prescribed.
Progressive supranuclear palsy (PSP) is a late-onset neurodegenerative disease involving the gradual deterioration and death of specific volumes of the brain. The condition leads to symptoms including loss of balance, slowing of movement, difficulty moving the eyes, and cognitive impairment. PSP may be mistaken for other types of neurodegeneration such as Parkinson's disease, frontotemporal dementia and Alzheimer's disease. The cause of the condition is uncertain, but involves the accumulation of tau protein within the brain. Medications such as levodopa and amantadine may be useful in some cases.
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.
In neurology, semantic dementia (SD), also known as semantic variant primary progressive aphasia (svPPA), is a progressive neurodegenerative disorder characterized by loss of semantic memory in both the verbal and non-verbal domains. However, the most common presenting symptoms are in the verbal domain. Semantic dementia is a disorder of semantic memory that causes patients to lose the ability to match words or images to their meanings. However, it is fairly rare for patients with semantic dementia to develop category specific impairments, though there have been documented cases of it occurring. Typically, a more generalized semantic impairment results from dimmed semantic representations in the brain.
Progressive nonfluent aphasia (PNFA) is one of three clinical syndromes associated with frontotemporal lobar degeneration. PNFA has an insidious onset of language deficits over time as opposed to other stroke-based aphasias, which occur acutely following trauma to the brain. The specific degeneration of the frontal and temporal lobes in PNFA creates hallmark language deficits differentiating this disorder from other Alzheimer-type disorders by the initial absence of other cognitive and memory deficits. This disorder commonly has a primary effect on the left hemisphere, causing the symptomatic display of expressive language deficits and sometimes may disrupt receptive abilities in comprehending grammatically complex language.
In neuropathy, primary progressive aphasia (PPA) is a type of neurological syndrome in which language capabilities slowly and progressively become impaired. As with other types of aphasia, the symptoms that accompany PPA depend on what parts of the brain's left hemisphere are significantly damaged. However, unlike most other aphasias, PPA results from continuous deterioration in brain tissue, which leads to early symptoms being far less detrimental than later symptoms.
Cognitive reserve is the mind's and brain's resistance to damage of the brain. The mind's resilience is evaluated behaviorally, whereas the neuropathological damage is evaluated histologically, although damage may be estimated using blood-based markers and imaging methods. There are two models that can be used when exploring the concept of "reserve": brain reserve and cognitive reserve. These terms, albeit often used interchangeably in the literature, provide a useful way of discussing the models. Using a computer analogy, brain reserve can be seen as hardware and cognitive reserve as software. All these factors are currently believed to contribute to global reserve. Cognitive reserve is commonly used to refer to both brain and cognitive reserves in the literature.
Mild cognitive impairment (MCI) is a neurocognitive disorder which involves cognitive impairments beyond those expected based on an individual's age and education but which are not significant enough to interfere with instrumental activities of daily living. MCI may occur as a transitional stage between normal aging and dementia, especially dementia due to Alzheimer's disease. It includes both memory and non-memory impairments. About 50 percent of people diagnosed with MCI have Alzheimer's disease and go on to develop Alzheimer's dementia within five years. MCI can also serve as an early indicator for other types of dementia, although MCI may remain stable or even remit.
Pseudodementia is a condition that leads to cognitive and functional impairment imitating dementia that is secondary to psychiatric disorders, especially depression. Pseudodementia can develop in a wide range of neuropsychiatric disease such as depression, schizophrenia and other psychosis, mania, dissociative disorders, and conversion disorders. The presentations of pseudodementia may mimic organic dementia, but are essentially reversible on treatment and doesn't lead to actual brain degeneration. However, it has been found that some of the cognitive symptoms associated with pseudodementia can persist as residual symptoms and even transform into true neurodegenerative dementia in some cases.
The NINCDS-ADRDA Alzheimer's Criteria were proposed in 1984 by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association and are among the most used in the diagnosis of Alzheimer's disease (AD). These criteria require that the presence of cognitive impairment and a suspected dementia syndrome be confirmed by neuropsychological testing for a clinical diagnosis of possible or probable AD; while they need histopathologic confirmation for the definitive diagnosis. They specify as well eight cognitive domains that may be impaired in AD. These criteria have shown good reliability and validity.
Leukoencephalopathy with neuroaxonal spheroids (LENAS), also known as adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), hereditary diffuse leukoencephalopathy with spheroids (HDLS) and pigmentary orthochromatic leukodystrophy (POLD) is an extremely rare kind of leukoencephalopathy and is classified as a neurodegenerative disease. LENAS is a cause of severe and subacute dementia that results from damage to certain areas of the brain. This damage is to a type of brain tissue called white matter and axon damage due to swellings which are termed spheroids.
Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems with language, disorientation, mood swings, loss of motivation, self-neglect, and behavioral issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to twelve years.
Amyotrophic lateral sclerosis (ALS), also known as motor neurone disease (MND) or Lou Gehrig's disease (LGD) in the United States, is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. ALS is the most common form of the motor neuron diseases. ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the abilities to eat, speak, move, and, lastly, breathe are all lost. While only 15% of people with ALS also fully develop frontotemporal dementia, an estimated 50% face at least some minor difficulties with thinking and behavior. Depending on which of the aforementioned symptoms develops first, ALS is classified as limb-onset or bulbar-onset.
Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor and non-motor systems. Symptoms typically develop gradually, with non-motor issues becoming more prevalent as the disease progresses. Common motor symptoms include tremors, bradykinesia, rigidity, and balance difficulties, collectively termed parkinsonism. In later stages, Parkinson's disease dementia, falls, and neuropsychiatric problems such as sleep abnormalities, psychosis, mood swings, or behavioral changes may arise.
Corticobasal syndrome (CBS) is a rare, progressive atypical Parkinsonism syndrome and is a tauopathy related to frontotemporal dementia. CBS is typically caused by the deposit of tau proteins forming in different areas of the brain.
LATE is a term that describes a prevalent medical condition with impaired memory and thinking in advanced age, often culminating in the dementia clinical syndrome. In other words, the symptoms of LATE are similar to those of Alzheimer's disease.
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