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Published on: November 28, 2018
by Women’s Brain Health Initiative:
Dementia is commonly thought of as a disease that affects older adults. While those aged 65 and over certainly do make up the vast majority of individuals with dementia, there is also a growing number of younger adults affected by the disease.
WHEN AN INDIVIDUAL UNDER THE AGE OF 65 IS DIAGNOSED WITH DEMENTIA, IT IS REFERRED TO AS “YOUNG-ONSET DEMENTIA” (YOD).
The number of individuals who have young-onset dementia is not known for certain. A 2014 review of scientific papers reporting on the prevalence of YOD, published in the European Journal of Neurology, found that the diversity of research designs has made direct comparison across studies difficult.
Accordingly, the researchers (Lambert and colleagues) shared the range of prevalence rates that had been reported in the various studies. Between 38 and 260 people per 100,000 were found to experience the onset of various types of dementia sometime between the age of 30 and 64. Prevalence rates were highest among those at the older end of that age range (as high as 420 people per 100,000 for those between the age of 55 and 64).
How do prevalence rates translate into the number of young adults afflicted with the disease?
Differences Between Young-Onset and Late-Onset Dementia
There are some differences between young-onset dementia and late-onset dementia that relate to the disease itself.
Although Alzheimer’s disease (AD) is the most common cause of dementia (regardless of the age-of-onset), the proportion of individuals living with AD is much lower among those with young-onset dementia (15-40%) than it is among those with late-onset dementia (50-70%). If you look at the young end of the YOD spectrum – people under the age of 45 – there are few with AD, and most of these are due to “familial Alzheimer’s disease,” which is a rare form of the disease passed on through genetics.
Familial Alzheimer’s disease is linked to three rare genes: APP, PSEN 1, and PSEN 2. These are different than the APOE gene that affects Alzheimer’s risk in general.
Frontotemporal dementia and Huntington disease are more prevalent in YOD, as are secondary dementias (those caused by, or related to, another recognizable disease such as chronic alcohol abuse, HIV, multiple sclerosis or traumatic brain injury. A wide range of rare metabolic, infectious or autoimmune disorders may also cause secondary dementias).
The high proportion of secondary dementias amongst younger individuals means that they are more likely to have treatable conditions causing their dementia (compared to older people). However, in order for interventions to be effective at improving cognition, they usually have to be given early in the course of the disease.
Different causes of dementia result in various symptoms and behaviour changes, and in YOD, memory problems may not be the first symptom to appear.
Early-onset dementia is another term used to describe young-onset dementia. However, “young-onset” is a clearer descriptor since “early-onset” can be misunderstood to mean early or mild dementia in someone over 65 years of age. An individual experiencing young-onset dementia may be in any stage of dementia: early, mid, or late.
EARLY SYMPTOMS OF YOD CAN VARY GREATLY AND MAY INCLUDE BEHAVIOURAL CHANGE, DEPRESSION, AND MILD COGNITIVE IMPAIRMENT, AS WELL AS PHYSICAL SYMPTOMS SUCH AS VISUAL IMPAIRMENT, GAIT DISORDER, AND SEIZURES.
Another difference between young-onset and late-onset dementia is the rate of disease progression. Rapid progression is more likely among those with YOD than those with late-onset dementia, although the course of YOD varies quite a bit from person to person and in some cases can remain stable indefinitely.
Challenges Unique to YOD
A diagnosis of dementia has a devastating impact on an individual and his or her family, irrespective of the age of onset. However, those with young-onset dementia face some unique challenges. To start with, it is common for younger individuals to experience delays in even receiving a proper diagnosis, or to receive a misdiagnosis.
Research indicates that on average it takes younger individuals with dementias of all types 4.4 years to receive a diagnosis, compared to 2.2 years for late-onset dementia of comparable severity. The delay in diagnosis for younger individuals is in part due to lack of awareness of YOD among the general public and family doctors (who are usually the first health professionals consulted). Many health care providers simply do not think to consider dementia as the potential reason for the presenting symptoms in a young person.
MORE OFTEN, THE SYMPTOMS OF DEMENTIA IN YOUNGER ADULTS ARE MISTAKEN AS SIGNS OF STRESS OR PSYCHIATRIC ILLNESS, PARTICULARLY WHEN COGNITIVE DECLINE IS NOT EVIDENT YET.
Additionally, individuals with young-onset dementia face the following age-related negative consequences that are not as likely to affect someone with late-onset dementia:
Dementia can be challenging to diagnose at any age. Currently, there is not a single test that confirms whether or not an individual has dementia. Instead, a diagnosis can only be made after a patient undergoes a comprehensive medical evaluation that includes an analysis of his or her medical history, a series of neuropsychological examinations, costly spinal taps and/or brain scans, and a report of behaviour history from an informant (because patients may not be aware of their own behaviour changes or may forget important details).
Remember, YOD is Fairly Uncommon
It is important to keep in mind that the vast majority of younger adults who experience challenges with memory do not have dementia. Rather, it is far more likely that they are experiencing cognitive impacts of stress, depression, or anxiety. It is nevertheless important that individuals of all ages – both young and old – focus on making healthy lifestyle choices that support brain health (e.g., physical activity, healthy diet, social connection, brain-stimulating hobbies) and then watch for unusual cognitive or behavioural symptoms.
If it appears that the symptoms of dementia are present, it is important to speak with a health professional as soon as possible. Again, since YOD is rare, it is most likely not YOD – but the sooner the diagnosis is received, the better, in order to increase the chances that a treatment could help reverse or halt the disease’s progression.
Source: MIND OVER MATTER v7
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