Younger Onset Dementia

Dementia is often thought of as an older person’s disease. In fact, between 5 and 10% of all people with dementia are under the age of 65. It is estimated that more than 5,000 people in New Zealand have younger onset dementia.

Any form of dementia beginning before the age of 65 is known as younger onset dementia. Younger onset dementia is also known as:

·       Young onset dementia

·       Early onset dementia

·       Presenile dementia

In general, the causes, treatment, and prognosis of younger onset dementia are similar to dementia in older adults; however, there are important differences that can present additional challenges to those experienced by people who develop dementia when they are over 65. For example, people with younger onset dementia may have significant financial and employment commitments, or they may be supporting young children and/or adolescents. For this reason, the information on these pages has been compiled to help people with younger onset dementia, their carers, and their loved ones. This information is relevant to anyone who is under the age of 65 and has been diagnosed with any form of dementia (including, but not limited to, Alzheimer’s disease, vascular dementia, Lewy body dementia, frontotemporal dementia (including both the behavioural and language variants), Parkinson’s disease dementia, and corticobasal degeneration).  

Symptoms

People with younger onset dementia experience a decline in cognitive ability that is severe enough to affect daily life. It is normal to experience minor lapses in memory and cognitive function, for example losing your car keys, but when a person has dementia, these lapses are severe enough to impact the person’s daily life. Younger onset dementia symptoms are often similar to those experienced by older adults with dementia. They include:

·       Memory problems

·       Language problems

·       Difficulty with daily activities (for example, preparing food, getting dressed, managing finances, using appliances etc.)  

·       Disorientation

·       Difficulty concentrating

It is important to note that this is not a complete list of symptoms. The type of cognitive decline that an individual with younger onset dementia experiences varies from person to person. If you suspect that you or someone you know is experiencing the symptoms of younger onset dementia, please discuss this with your GP.

Types

 

Dementia is an umbrella term used to describe a progressive, gradual decline in cognitive functioning (e.g. in memory, language skills, planning, problem solving, reasoning). These changes in cognitive functioning are significant enough to impact on the person’s ability to function in their usual activities. There are many underlying conditions that cause dementia. The condition that most commonly causes younger onset dementia is Alzheimer’s disease. Other conditions that commonly cause younger onset dementia are vascular dementia, frontotemporal dementia, and Lewy body dementia. These four conditions account for over half of all cases of younger onset dementia. There are many other less common causes of younger onset dementia. The following is a list of some of the causes of younger onset dementia, with a description of their key features.

  • Alzheimer’s Disease:

Around a third of younger onset dementia cases are caused by Alzheimer’s disease. Typically, the earliest symptom of Alzheimer’s disease is memory impairment. When Alzheimer’s disease is diagnosed in someone under the age of 65, it is known as early-onset Alzheimer’s disease, or younger-onset Alzheimer’s disease. Up to 5% of all people with Alzheimer’s disease are diagnosed before the age of 65. Alzheimer’s disease is progressive, which means that symptoms get worse over time. In general, the symptoms, prognosis, and management of early-onset Alzheimer’s disease are similar to those of Alzheimer’s disease in older adults. However, younger people are more likely to have an ‘atypical’ form of Alzheimer’s disease, which means that it may be more difficult to diagnose.
     

  • Frontotemporal dementia (FTD):

Frontotemporal dementia is a common cause of younger onset dementia. The majority of people with frontotemporal dementia develop symptoms when they are under 65. Frontotemporal dementia used to be called Pick’s disease, and some doctors still use this term. Other terms that are used to describe frontotemporal dementia are frontal lobe disorders, frontotemporal disorders, and frontotemporal degeneration. Some people with frontotemporal dementia also have amyotrophic lateral sclerosis, a movement disorder that is also known as motor neuron disease or Lou Gehrig's disease. This is known as FTD-ALS.  

There are two major subtypes of frontotemporal dementia: behavioural variant and language variant. Language variant frontotemporal dementia is also known as primary progressive aphasia.

i.     Behavioural variant frontotemporal dementia (bvFTD):

The main factor that distinguishes behavioural variant frontotemporal dementia from early-onset Alzheimer’s disease is that behavioural change is often the first noticeable symptom, and memory loss tends to be less prominent. Common early symptoms of behavioural variant frontotemporal dementia are personality change, poor judgement, socially inappropriate behaviour, apathy, and lack of empathy.

ii.     Language variant frontotemporal dementia:

Language variant frontotemporal dementia is also known as primary progressive aphasia. The key symptom of language variant frontotemporal dementia is a gradual decline in the ability to speak, read, write, and understand what others are saying. It is further divided into three sub-types, based on the specific language skills that are affected:

1.     Semantic variant primary progressive aphasia (also known as semantic dementia)

2.     Non-fluent variant primary progressive aphasia (also known as agrammatic variant primary progressive aphasia)

3.     Logopenic variant primary progressive aphasia (sometimes the logopenic variant is considered to be a sub-type of Alzheimer’s disease)

 

  • Vascular dementia:

Vascular dementia is a common cause of younger onset dementia. Vascular dementia occurs when the blood supply to the brain is blocked. It is closely linked to cardiovascular diseases such as stroke. In general, the symptoms, prognosis, and management of vascular disease in people under 65 are similar to those of vascular disease in older adults.

  • Lewy body dementia:

Lewy body dementia (also known as dementia with Lewy bodies) is a common cause of younger onset dementia. Visual hallucinations, fluctuations in cognitive ability, and REM sleep behaviour disorder (in which people physically act out their dreams) are common in Lewy body dementia. Many people with Lewy body dementia have movement symptoms that are similar to those seen in Parkinson’s disease, including rigid muscles and slowness of movement. The main difference between Lewy body dementia and Parkinson’s disease dementia is that the cognitive symptoms appear more than a year after the movement symptoms in Parkinson’s disease dementia, whereas the cognitive symptoms appear within a year of the movement symptoms in Lewy body dementia.

  • Parkinson’s disease dementia:

Some people with Parkinson’s disease eventually develop dementia. These cases are called Parkinson’s disease dementia. Visual hallucinations and REM sleep behaviour disorder (in which people physically act out their dreams) are common in Parkinson’s disease. The main difference between Lewy body dementia and Parkinson’s disease dementia is that the cognitive symptoms appear more than a year after the movement symptoms in Parkinson’s disease dementia, whereas the cognitive symptoms appear within a year of the movement symptoms in Lewy body dementia.

  •  Corticobasal degeneration:

Corticobasal degeneration (also known as corticobasal syndrome) is a rare cause of younger onset dementia. In addition to the cognitive symptoms, it is characterized by movement symptoms that are similar to those seen in Parkinson’s disease, including rigid muscles and trouble initiating movement. Like frontotemporal dementia, corticobasal degeneration involves degeneration of parts of the brain called the frontal lobe and the temporal lobe. Corticobasal degeneration is sometimes described as a sub-type of frontotemporal dementia.

Diagnosis of cause

It typically takes longer for people with younger onset dementia to receive a diagnosis than it does for older people with dementia. Getting an accurate diagnosis can be a long and frustrating process.  This may partly be due to the lack of awareness that dementia can affect younger people. People with younger onset dementia are sometimes misdiagnosed as having depression or stress before they are accurately diagnosed. An early and accurate diagnosis is very important so that the person with younger onset dementia and their family can plan for the future. It’s also very important because it allows the person’s clinicians to determine the best way to manage their condition.

In New Zealand, a person who is suspected of having younger onset dementia will typically be referred to a specialist by their GP. New Zealand GPs have access to Cognitive Impairment Pathways that guide them through the assessment of people who might have dementia. In some cases, the GP may not consider the possibility of dementia because the person is under 65. In these cases, it may help to request support from your local dementia association.

Most important for diagnosis is establishing the history of symptoms from the person and another informant, usually a family member. This will include information about how and when changes occurred and their progression, mental/emotional symptoms, other illnesses, usual functioning, life stresses and family history.

The GP will generally perform cognitive screening on the first visit. These screening tests alone do not determine if a person has younger onset dementia. They are used to quickly determine if a person needs to undergo a more thorough assessment by a specialist. It is important to note that some people with younger onset dementia will have a normal score on these screening tests, because the screening tests are not sensitive to all of the conditions that cause younger onset dementia.

The GP will typically refer the person to a neurologist or a psychiatrist and/or a neuropsychologist for a thorough assessment if they suspect younger onset dementia. The GP might refer the person to a Memory Clinic if there is one available. The tests that the specialists use are the same as those used in suspected cases of dementia in older adults.

Physical (including neurological) examination may detect abnormalities that suggest that something else, possibly treatable, is causing confusion.

Laboratory testing will check for other causes of memory loss and confusion and ensure that the

person is in the best health possible. A CT scan, MRI or other special scans will be ordered as a standard procedure for people with younger onset cognitive impairment. However, a brain scan alone cannot diagnose the underlying cause of dementia. 

It is important to note that in most cases there is no one test that confirms the cause of younger onset dementia. A diagnosis is only made after a comprehensive medical assessment, which may involve more than one specialist. In some cases, it may be necessary to re-assess the person up to a year later to confirm the diagnosis.