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. [4] Although used in the past, the term presenile dementia is no longer in favor.
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 3.9 million people aged 30–64 worldwide, 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. [5] [6] Similar to late onset dementia, the prevalence of early onset dementia increases exponentially with age, doubling every five years of age. [5] 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. [7]
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. [8] The presence of one or multiple of these chronic conditions is more predictive of early onset dementia compared to late onset dementia. [8] 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. [9] Additionally, depending on the etiology of early onset dementia, family history may be a significant risk factor, especially for Alzheimer's early onset dementia. [6]
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. [10] 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. [5] 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. [11] The diagnostic work-up of early onset dementia includes combinations of detailed history taking, neuroimaging, behavioral testing, and genetic testing. [11] 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. [12] Despite this specific services for those with early onset dementia are rare. [13] 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. [13]
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. [10] 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. [10] 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. [10]
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. [10] Average survival time is approximately 6–10 years following diagnosis for both men and women, with variability depending on specific type of dementia. [5] 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. [10]
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.
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.
Tauopathies are a class of neurodegenerative diseases characterized by the aggregation of abnormal tau protein. Hyperphosphorylation of tau proteins causes them to dissociate from microtubules and form insoluble aggregates called neurofibrillary tangles. Various neuropathologic phenotypes have been described based on the anatomical regions and cell types involved as well as the unique tau isoforms making up these deposits. The designation 'primary tauopathy' is assigned to disorders where the predominant feature is the deposition of tau protein. Alternatively, diseases exhibiting tau pathologies attributed to different and varied underlying causes are termed 'secondary tauopathies'. Some neuropathologic phenotypes involving tau protein are Alzheimer's disease, frontotemporal dementia, progressive supranuclear palsy, and corticobasal degeneration.
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 Alzheimer's disease. It includes both memory and non-memory impairments. The cause of the disorder remains unclear, as well as both its prevention and treatment, with some 50 percent of people diagnosed with it going on to develop Alzheimer's disease within five years. The diagnosis 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.
Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens, and 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.
Sundowning, or sundown syndrome, is a neurological phenomenon associated with increased confusion and restlessness in people with delirium or some form of dementia. It is most commonly associated with Alzheimer's disease but is also found in those with other forms of dementia. The term sundowning was coined by nurse Lois K. Evans in 1987 due to the timing of the person's increased confusion beginning in the late afternoon and early evening. For people with sundown syndrome, a multitude of behavioral problems begin to occur and are associated with long-term adverse outcomes. Sundowning seems to occur more frequently during the middle stages of Alzheimer's disease and mixed dementia and seems to subside with the progression of the person's dementia. People are generally able to understand that this behavioral pattern is abnormal. Research shows that 20–45% of people with Alzheimer's will experience some variation of sundowning confusion. However, despite lack of an official diagnosis of sundown syndrome in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), there is currently a wide range of reported prevalence.
Amyotrophic lateral sclerosis (ALS), also known as motor neurone disease (MND) or Lou Gehrig's disease 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 dementia (PDD) is dementia that is associated with Parkinson's disease (PD). Together with dementia with Lewy bodies (DLB), it is one of the Lewy body dementias characterized by abnormal deposits of Lewy bodies in the brain.
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.
Facial onset sensory and motor neuronopathy, often abbreviated FOSMN, is a rare disorder of the nervous system in which sensory and motor nerves of the face and limbs progressively degenerate over a period of months to years. This degenerative process, the cause of which is unknown, eventually results in sensory and motor symptoms — the former consisting mainly of paresthesia followed by numbness, and the latter in muscle weakness, atrophy, and eventual paralysis. FOSM is characterized by sensory and motor loss beginning in the face and spreading to involve an increasingly larger area including the scalp, upper arms and trunk. The muscles or respiration and swallowing are commonly affected. In many ways, it is reminiscent of the much better known condition amyotrophic lateral sclerosis, with which it is closely related. There is no cure; treatment is supportive. Life expectancy may be shortened by respiratory complications arising from weakness of the muscles that aid breathing and swallowing. It was first described in four patients by Vucic and colleagues working at the Massachusetts General Hospital in the United States; subsequent reports from the United Kingdom, Europe and Asia point to a global incidence of the disease. It is thought to be exceptionally rare, with only approximately 100 individuals described to date in the medical literature.
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