Doctors do not understand why most cases of early-onset Alzheimer's appear at such a young age. But in a few hundred families worldwide, scientists have pinpointed several rare genes that directly cause Alzheimer's. People who inherit these rare genes tend to develop symptoms in their 30s, 40s and 50s.
People diagnosed with ARBD tend to be in their 40s and 50s, and it is more common in men. ARBD is caused by a lack of thiamine (vitamin B1), direct damage to nerve cells from alcohol, head injuries (caused for instance by falls or fights) and a poor diet. At least 1 in 10 younger people with dementia may have ARBD.
The biggest risk factor for dementia is ageing. This means as a person gets older, their risk of developing dementia increases a lot. For people aged between 65 and 69, around 2 in every 100 people have dementia. A person's risk then increases as they age, roughly doubling every five years.
We all inherit a copy of some form of APOE from each parent. Those who inherit one copy of APOE-e4 from their mother or father have an increased risk of developing Alzheimer's. Those who inherit two copies from their mother and father have an even higher risk, but not a certainty.
A very small number of young onset Alzheimer cases are caused by a faulty gene passed down in families. This is called 'familial Alzheimer's disease' (FAD) or 'young onset inherited' Alzheimer's. It usually affects many members of the same family at every generation, typically in their 30s, 40s or 50s.
There may be specific instances when an individual living with Alzheimer's should discuss genetic testing with their physician, as the results could impact a treatment decision. In addition, a physician may utilize genetic testing as part of the diagnostic process for more rare types of dementia.
What is early-onset Alzheimer disease? Alzheimer disease is the most common form of dementia. It affects your memory, thinking, and behavior. It often progresses to the point where it affects daily activities and functions.
Family history by the numbers
In absolute numbers, a 2% annual risk means that two out of 100 65-year-olds will develop dementia every year. Family history raises the 2% annual risk by about 30%, to 2.6% per year. That means going from 20 cases in a group of 1,000 to 26 in 1,000, or six additional cases in 1,000.
Introduction: The five-word test (5WT) is a serial verbal memory test with semantic cuing. It is proposed to rapidly evaluate memory of aging people and has previously shown its sensitivity and its specificity in identifying patients with AD.
The main sign of mild cognitive impairment is a slight decline in mental abilities. Examples include: Memory loss: You may forget recent events or repeat the same questions and stories. You may occasionally forget the names of friends and family members or forget appointments or planned events.
Delirium
Delirium can be caused by chronic illness, certain medications, infection or surgery, and the symptoms—confusion, disorientation and memory impairment—look a lot like those of dementia.
The Mini-Cog test.
A third test, known as the Mini-Cog, takes 2 to 4 minutes to administer and involves asking patients to recall three words after drawing a picture of a clock. If a patient shows no difficulties recalling the words, it is inferred that he or she does not have dementia.
One study in Norway found that young onset dementia occurred in 163 out of every 100,000 individuals; that's in less than 0.5% of the population. So, if you're younger than 65 and you've noticed some trouble with your memory, you have a 99.5% chance of there being a cause other than dementia.
A 19-year-old is the youngest person to be diagnosed with Alzheimer's disease – the cause is a mystery.
It mainly affects older people but not all people will get it as they age. Things that increase the risk of developing dementia include: age (more common in those 65 or older)
The international research team, based in the UK, Finland, US, France, New Zealand and Japan, report that lifelong social participation could alleviate dementia risk by increasing cognitive reserve, and through brain maintenance by reducing stress and improving cerebrovascular health.
Meta-analyses showed age-standardized incidence rates increased from 0.17/100,000 person-years in age 30-34 years, to 5.14/100,000 person-years in age 60-64 years, resulting in a total incidence rate of 11/100,000 person-years in age 30-64 years. This corresponds to an annuals incidence of 370,000 new cases every year.
The term early onset dementia refers to dementia that first occurs in a person under age 65. The dementia may be caused by Alzheimer's disease or other diseases and conditions.
The Montreal Cognitive Assessment (MoCA) is a tool that helps healthcare professionals detect mild cognitive impairment and Alzheimer's disease in people. A 2021 study found that it is a better measure of cognitive function than the MMSE. It consists of 30 questions that take 10–12 minutes to accomplish.