Thinking Clearly About Down Syndrome and Alzheimer’s

The LowDOWN: A Down Syndrome Podcast recently welcomed Dr. Elizabeth Head to discuss Down syndrome and Alzheimer’s disesase. Dr. Head earned a Master’s in Psychology and a PhD in Neuroscience at the University of Toronto. She received postdoctoral training at the Institute for Memory Impairments and Neurological Disorders at the University of California – Irvine. Dr. Head moved to the University of Kentucky in January of 2009 and served as a Professor and Associate Director of Education at the Sanders-Brown Center on Aging. Now at the University of California – Irvine, she is a Professor and Vice Chair for Research in the Department of Pathology & Laboratory Medicine. Dr. Head has dedicated over 25 years to the study of aging and Alzheimer’s disease with a focus on people with Down syndrome. She has published over 200 papers and her research is supported by the National Institutes of Health. The goal of her research is to contribute to the development of interventions that will promote healthy aging in people with Down syndrome. This article is a lightly edited transcript of a portion of The LowDOWN Podcast episode, produced by the Down Syndrome Resource Foundation. The full conversation can be found here.

The LowDOWN: Can you begin by defining Alzheimer’s disease and dementia, which are often used interchangeably?

Dr. Elizabeth Head: Like you say, a lot of people interchange Alzheimer’s disease with dementia. Dementia is a clinical set of signs including a loss of memory and a loss of function, such as forgetting where we parked the car. These symptoms can happen for a number of different reasons, but the most common cause of dementia is Alzheimer’s disease, in which people have plaques and the tangles in their brains. But there are other kinds of dementia that are caused by other diseases in the brain. For example, Lewy body disease looks slightly different. It certainly is dementia, but it’s caused by a different set of proteins that are abnormal in the brain. So, dementia is the umbrella term, and underneath that you have specific types of dementia like Alzheimer’s disease, Lewy body disease, and frontotemporal dementia.

LD: With respect to the Down syndrome population, when they develop dementia, is it always Alzheimer’s, or have other forms of dementia also been observed?

EH: In my personal opinion, it’s almost always Alzheimer’s disease. I believe there are a few case reports out there suggesting that one person with Down syndrome had Lewy body disease. If that happens, it’s incredibly rare. I think we can be pretty confident when we think about what interventions we are going to design for the future.

LD: What are some of the symptoms or characteristics that you see in Alzheimer’s disease, and are they different for people with Down syndrome?

EH: In the general population, usually the earliest sign is memory loss, although there can be other profiles or variants of Alzheimer’s disease that show up early, looking a little bit different. But memory loss is the key thing. That then progresses to language problems and difficulty with objects in space and placement of things, before transitioning into more behavioural and psychiatric problems. It just gets progressively worse, until the person really can’t take care of themselves.

For people with Down syndrome, it’s essentially the same pattern. Families will report memory changes, but the most common thing we hear from families is a change in behavior. The person becomes very withdrawn, not interested in the same hobbies and activities as they used to be. That’s often what really triggers families: something’s changing. What we’re looking for is change over time. A single visit to a clinician may give them a good guess at what’s going on, but we really firm up that diagnosis when we see that person again after a period of time, and there’s been a decline.

LD: We should note, for families who are seeing behavioural changes, there could be many other causes besides Alzheimer’s, some of which are temporary and very treatable. It’s important to see your doctor before assuming that you’re dealing with Alzheimer’s.

EH: I’m really glad you mentioned that because I am seeing more discussion of regression, which typically happens in younger adults. If it’s not in the age range where we start to think about Alzheimer’s disease, there are likely other explanations, and it could be something as simple as environmental changes.

LD: Speaking of which, what is the age when Alzheimer’s becomes an issue for people with Down syndrome?

EH: 40-years-old is a pretty comfortable cutoff. However, we’re starting to see the age shift later, more towards 50. That’s fabulous, because it means people are better managing their health and lifestyle to delay the onset.

LD: What are the current incidence rates? Can we expect all individuals with Down syndrome to develop Alzheimer’s as they age?

EH: Unfortunately, the overall average is that 90% of people with Down syndrome will develop the clinical signs of dementia and Alzheimer’s disease at some point. When we look back at all the different studies of groups of people around the world, it never quite reaches 100% even in the oldest people with Down syndrome – there are 10-15% of people with Down syndrome who get into their sixties and even early seventies without showing change in cognition. This happens in the general population as well, of course: certain people live to be very old, and though they have a lot of the risk factors, they don’t develop dementia. We are very hopeful that we are going to get a better handle on this and see those numbers go up.

LD: There must be some things we can learn from those who don’t develop it, to advance prevention and treatment.

EH: That’s what’s so fascinating. Individuals with Down syndrome are a gateway to learning more about Alzheimer’s in general. We are working to determine the genetic and physiological components of Down syndrome that contribute to the development of Alzheimer’s, which helps everyone – those with and without Down syndrome.

In the general population, people develop Alzheimer’s disease anywhere between 65 and 125 – that’s kind of a made up a number, but there’s a huge age range for when a person might begin to decline. Plus, that decline could be Alzheimer’s, it could be Lewy disease, there could be many things contributing. So, when you are trying to understand biomarkers such as fluid measures or interpret neuroimaging brain pictures, it gets really complicated.

In contrast, for people with Down syndrome, because of their genetics and the extra copy of chromosome 21, the changes in their brains reflecting Alzheimer’s disease are strongly age dependent. By age 40, we typically see full-blown Alzheimer’s disease in the brain, but that isn’t necessarily reflected in their change of function. In their thirties, they’re starting to develop the earliest signs, but in their twenties, they seem to be okay.

As a result, we can better understand what’s coming first in the order of events that leads to disease, which is really hard to do in the general population – in fact, it’s almost impossible. These age-related changes in people with Down syndrome tell us a huge amount about how Alzheimer’s disease develops, and which markers in the blood or in an MRI signify that a person is on that trajectory. That’s why we can take a lot of what we learn from people with Down syndrome and not only use it to help find ways to prevent Alzheimer disease in Down syndrome but also apply it to the general population.

LD: Do you have any advice for families who are navigating an Alzheimer’s diagnosis now with their loved one with Down syndrome?

EH: The advice I would give is to always keep a positive attitude. I’m sorry if that’s a little Pollyanna, because I know for families going through this process, it’s incredibly hard. There are going to be behaviours that are hugely challenging to deal with, and there are not a lot of resources out there. But don’t give up on trying to manage those behavioural changes, which can be aided by medication. Keeping up with the person’s routine is very valuable. And of course, it’s never too late to introduce healthy lifestyle habits, even though it may be challenging. Take walks; try new foods. Engage in social activities as much as possible, and make sure the person is getting enough sleep.

Finally, don’t neglect caregiver respite, which should be part of the treatment plan. A break for the person taking care of a family member with Down syndrome is critically important. We’re treating the whole family, not just the person who has the disease.

Resources:

Down Syndrome + Alzheimer’s Disease Information Page (DSRF)

Mental Health and Aging: An Interview with Dr. Brian Chicoine

Down Syndrome and Alzheimer’s Disease: Supporting Communication (Video Presentation)

National Down Syndrome Society: Alzheimer’s Disease and Down Syndrome

National Task Group on Intellectual Disabilities and Dementia Practices