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Young-onset dementia
Young-onset dementia(YOD) is a brain disease which is linked to dementia. Patients with YOD are diagnosed with dementia. The difference, however, with normal dementia is that these patients are below the age of 65, while dementia mostly occurs among people aged 65 and above That is why the research on dementia has focused on the elderly people. Nowadays however, more and more younger people suffer from dementia. Unfortunately the symptoms of these young people are often not linked with dementia.

Other terms for YOD are Younger-onset Dementia and Younger people with dementia.

Definition
Earlier the term Presenile dementia was used but this term was not longer favoured because it can be mistaken to mean early or mild dementia. That is why they now use YOD. The term refers to people younger than 65 years who suffer from dementia. This age limit has no specific biological significance, but it is used as a cutoff point because this is often the age people retire. Dementia (also called a neurological disorder) is defined according to the following criteria:
 * 1) there is evidence of significant cognitive decline from a previous level of performance in one or more cognitive domains. this could be:


 * 1) * learning and memory
 * 2) * language
 * 3) * executive function
 * 4) * complex attention
 * 5) * perceptual and motor function
 * 6) * social cognition
 * 7) these cognitive deficits interfere with independence in everyday activities. At a minimum, assistance should be required with complex instrumental activities of daily living, such as paying bills or managing medications.
 * 8) these cognitive deficits do not occur exclusively in the context of a delirium
 * 9) these cognitive deficits are not better explained by another mental disorder (eg, major depressive disorder, schizophrenia)

Causes
Young onset of dementia (YOD) rates are increasing. Prevalence in the age group 45-65 is currently 67 to 81 per 100,000, which approximates a total of 10.000 YOD patients in The United Kingdom. There are different sorts of dementia which may start at an age under 65. The main type is Alzheimer.

Early onset of Alzheimer’s disease seemed to be relatively uncommon at about 1-2% of Alzheimer’s patients. However, it has been shown that this rate of EOAD is actually 5,5%. Several causes for YOD have been described:
 * In some patients, the early onset of dementia is caused by genetic deficit in metabolism. There is (partial) inactivity of a specific enzyme, which leads to abnormal aggregation in lysosomes or peroxisomes.
 * In approximately 10% of YOD patients, the disease is caused by chronic alcohol abuse.

Some seem to be specifically important in the causation of Alzheimer’s disease
 * Alzheimer’s disease can be related to inheritable mutation of the Presenilin (PS) 1 gene on chromosome 14. According to the amyloid hypothesis, it is a pathogenic cascade that causes Alzheimer’s disease, though the accumulation of β-amyloids.
 * If structures in the medial temporal lobe (especially the hippocampus) become involved at an early age, this may lead to the episodic memory loss – forgetting of daily events.
 * FTLD – frontotemporal dementia with parkinsonism – occurs when there is a mutation in the tau gene, which lies on the 17th chromosome.

Huntington’s disease may be cause by CAG trinucleotide, which repeats itself in an excessive manner. This gene’s function is to encode the protein ‘huntingtin’, which function is unknown. Alzheimer’s Disease originates when proteins build up in the brain, these structures of proteins are called: plaques and tangles. A different kind of Alzheimer’s disease is familial Alzheimer’s disease, this is inherited and caused by mutations in three genes. Also, people with Down Syndrome have a higher chance to develop young onset dementia, because people with down syndrome have an extra copy of chromosome 21. This chromosome carries the protein which forms the plaques in the brain. Another form of YOD is vascular dementia, this is caused when there are problems with the blood supply of the brain. This form is related to diabetes and cardiovascular diseases for example stroke or heart diseases. There is also a genetic kind of vascular dementia, this is caused via defects in a gene, NOTCH3. It follows a similar pattern to familial Alzheimer’s disease. A third form of YOD is caused when protein builds up in the brain, this protein is calles: Lewy bodies. There is also a form of alcohol related dementia, this is caused when people drink extreme amounts of alcohol on a regular basis. Other causes are: lack of vitamin B1 (thiamine), damage to nerve cells, a poor diet and head injuries. Other, more general causes of dementia include; hormone disorders, vitamin shortage, infections and sleep apnea.

Symptoms
Symptoms for dementia in young people are often misunderstood for other common causes like depression, anxiety and other illnesses. Also different behaviour is compared with changes in young peoples life. Because of the problems there is a delay in diagnosing YOD Because of this they suffer from self loss which sometimes leads to job loss and financial issues. If they lose the job, they also lose a part of their social contract and a part of the meaning of their life. People suffer mostly form the same symptoms like older people with dementia some of them are: When people with dementia are put in abnormal situations there may be a sudden behavioral change, from crying to anger, this is called a catastrophic reaction.
 * People with YOD suffer from the loss of normal life activities like being a parent, spouse or a financial supporter which leads to loss of self and identity.
 * Also because of the young age people with YOD suffer more form the dementia than older people which makes them a bigger burden for caregivers than older people. They experience more psychological problems. That is the reason why caregivers really need to be educated to take such a burden.
 * Balance problems
 * Speech and language difficulties
 * Perception and visual problems
 * Memory distortions
 * But also behavioral problems like
 * 1) depression
 * 2) anxiety
 * 3) elated mood
 * 4) abnormal motor behavior
 * 5) changes in sleep or apatite
 * 6) irritability
 * 7) apathy
 * 8) delusions
 * 9) disinhibition and impulsivity

Diagnosis
An early diagnosis for YOD is important. It helps the carers and family of the patient to understand the prognosis, but it also creates an opportunity for them to prepare for management of the illness in the future. However, the difficulties in getting a diagnosis of dementia seem to be greater before the age of 65 years. To diagnose YOD, a structured approach is needed. This way any diseases with similar symptoms can be excluded. Before someone can be diagnosed with YOD, their cognitive and behavioural deficits need to be determined, as well as the involvement of the nervous system. A physical examination is also useful since the cognitive deficits can be caused by an influence outside the nervous system.

The cognitive assessment includes different domains such as
 * memory
 * language
 * literacy skills
 * executive functions

Although cognitive examination can be useful, a neuropsychological assessment is also necessary. The patients’ results of these neuropsychological tests will be compared with age-related normative data.

Pharmacological treatment
There are few specific treatments available for YOD, but it is often paired with symptoms of depression. To relieve these symptoms Selective serotonin reuptake inhibitors can be prescribed and since Tricyclic antidepressants worsen cognition these are not preferred.

Approved treatment for YOD forms of adult neurodegenerative diseases are similar to those for late-onset dementia. Acetylcholinesterase inhibitors may offer symptomatic benefit in adult neurodegenerative diseases but do not stop the disease progression. The use of these medications is still under investigation.

Non-pharmacological treatment
People with YOD often have an impaired judgement, so it is very important to make sure they are in a safe enviroment. Also distracting the patients with exercise or activities such as word puzzles plays an important role. Occupational and speech therapists could assist with other daily activities and if necessary alternative forms of communication. Also support groups can be helpful for the patient and their caregivers. It is important to acknowledge the burden of the caregivers, YOD strikes patients during their most productive years, which leads to them leaving the work force and hereby financial stress. Caregivers experience psychological and emotional struggles such as social isolation. So treatment of YOD must also target caregivers to ensure they can get support in their responsibilities.

Risks and prevention
There are several causes that increase the risk for YOD. Low cardiovascular fitness and low cognitive performance at a young age can form a serious risk factor.

several other matters that create higher risk for YOD :
 * alcohol intoxination
 * drug intoxination
 * depression
 * low cognitive function
 * high systolic blood pressure
 * stroke
 * genetics

An education shorter than 12 years and exposure to chemicals like pesticides and fertilizers can increase risk.

Hypertension therapy can reduce vascular risk factors. A lifestyle change can also reduce risk, for example decreasing alcohol and tabacco usage.