Behavioural symptoms and dementia progression

Behavioural symptoms are common in dementia and cause often the greatest distress to the person with dementia and their carers. There have been also suggestions that behavioural symptoms can lead to a faster dementia disease progression. What is the scientific evidence for that? And if so, which behavioural symptoms are affecting the dementia disease progression? And what can we do about this?

Let’s find out.

Dementia progression

Nearly every person with dementia wants to know after a diagnosis ‘How much time do I have left?’. It is a fair question, as people want to get their affairs in order and want to enjoy as much quality of life with the time they have left. However, this question is often dreaded by clinicians and healthcare professionals. This is not because the clinicians do not want to talk about it but it is in fact quite difficult to determine for an individual person with dementia how slow or fast they will progress in their disease. We know quite a lot about disease progression or how much time people with dementia have left on average but not for the individual. The average disease progression can also differ greatly for different types of dementia, with Alzheimer’s disease having on average a disease duration of 6-7 years, whereas for semantic dementia it is 12 years and for the people with combined Amyotrophic Lateral Sclerosis & Frontotemporal dementia 1.5 years. Let’s take Alzheimer’s disease as an example. Despite Alzheimer’s disease having an average disease duration of 6-7 years, some people with Alzheimer’s disease might live with the disease much longer, with some reported cases living for several decades with the disease whereas others might only live a year or two. So, the disease duration might differ from that by quite a lot – either being shorter or longer. The other factor to consider is that the disease duration is often calculated from the time of diagnosis, which can also differ quite significantly from the onset of symptoms. For example, many people might have symptoms for many years without having a diagnosis which can affect these disease duration numbers significantly.

We should realise now that the range of disease duration has a large variability not only between different dementias but also between individuals with the same type of dementia. It should come, therefore, not as a surprise that clinicians are often reluctant to give a prediction of disease duration for an individual, even though that is what most people would want. But clearly, saying to someone you will have 5 years to live and they live on for another 12 years or die after 2 years only, is not only upsetting to the person with the disease but also their family. “Didn’t the doctor say we had 5 years to live? But look at me I am still living 10 years on. What do those doctors know anyway!” I think any clinicians might be happy with a longer disease duration for a person with dementia but of course, having a shorter disease duration will likely be very upsetting to the person and their family who were expecting many more years.

So, why do we not know more about the individual disease progression in dementia?

There are various reasons for this. For one, the research into disease progression is challenging as it is not easy to follow people with dementia and their families across the whole disease duration. People with dementia might move from their home to different care facilities making it difficult to keep track of people for research. People with dementia and their families might be also more reluctant to take part in research over time, as the demands of the disease are different towards the latter stages than the earlier stages. In other words, they have – understandably – other problems to worry about than taking part in some research study. But these are only some of the reasons, there are a whole plethora of other reasons. However, it makes clear that following individuals over time and their disease can be challenging and therefore research evidence has been limited to date.

We know more about the total disease duration, as we can often access the date of diagnosis and the date of death via healthcare records. Indeed, the average disease duration times are mostly based on those studies. But such studies do not tell us anything about how people progressed through the disease. Specifically, which factors determine whether people progressed faster or slower? Or the rate of progression, do people just continuously decline or do they ‘plateau’ at certain stages, where the disease is seemingly not progressing until the progression starts again? Anecdotally, many factors have been flouted that might affect dementia disease progression but what is the scientific evidence for those factors determining dementia disease progression?

Factors determining dementia disease progression

We know already that research studies of dementia disease progression over the long term can be very challenging to conduct. Still, several previous and ongoing studies have braved this challenge and have followed people with dementia over years or in some cases even decades. But even these brave research studies face another, ultimate, problem that the number of people they are following is not sufficient enough to make individual predictions for dementia progression.

What do I mean by that?

There is an irony that if we want to predict how an individual progresses we actually need to know first how many other people progress in the disease. If we know how a lot of other people with disease progressed we can identify people who were similar to the person we want to predict. For example, Mrs Smith might be quite different from Mrs Jones but has a similar background, physical health, disease(s) as Mrs Williams. Ideally, we want to use Mrs Williams information to predict Mrs Smith and not that of Mrs Jones. This should allow us to make much better disease progression predictions for Mrs Smith. However, for that, we need to find many cases similar to Mrs Williams, as we want to make sure that it is really those factors that determine the disease progression in Mrs Smith. In essence, we need large databases of people/patients which we can consult to find similar cases. Unfortunately, few such long-term databases exist for dementia and hence it can be very difficult to predict for a specific person how their dementia progression might be, which will ultimately also determine their disease duration. This approach is also referred to as personalised medicine since we make a more personalised prediction for people with dementia and is now very ‘all the rage’ in medical research. The irony is of course, that we need very large and impersonal data to make the prediction more personalised since we need to identify similar people via large databases.

But this personalisation not only allows better prediction of how someone with dementia might progress in the disease. We can also try to better treat or prevent adverse events in someone’s disease progression. Since we know from other similar cases which factors determined their disease progression, we can try to improve those factors or avoid risks. For example, we know that Mrs Smith has not only dementia but also Type II Diabetes. From similar cases to Mrs Smith we know that people with dementia who have Type II Diabetes, that the regulation of their blood glucose levels can become a challenge and can lead to hypoglycaemic (too little blood sugar) events. Such hypoglycaemic events carry a high risk of falls and fractures in dementia, often requiring hospitalisation and subsequent care home placement. Knowing therefore beforehand that the management of blood glucose is vital for Mrs Smith to stay as healthy and as long as possible at her own home will change how we manage or treat her Type II Diabetes. If we do this correctly, we can change her disease progression significantly and potentially prolong her life significantly. This is of course just an example, we can take many specific factors which determine disease progression but once we know for a specific person which factors are the most critical one, we can make a significant difference to their dementia disease progression.

This nicely brings us back to our original question. Do behavioural symptoms also determine the disease progression in dementia?

Behavioural problems and dementia progression

Whether behavioural problems determine disease progression has been a question for a long time. There have been occasional reports that having behavioural symptoms (clinicians refer to these also as neuropsychiatric symptoms, in case you come across this) significantly affects dementia disease progression.

But does this mean all people with dementia? How about people with dementia who have few behavioural symptoms from the outset of the disease, such as Alzheimer’s disease? Do they differ from people who have behavioural symptoms from diagnosis onwards? And are all behavioural symptoms affecting diseases progression or only a few specific ones?

So many valid questions, and yet so few answers – until recently.

The problem that we did not know most of these answer until recently, was again due to having too small dementia databases which did not follow people over longer-term or through the whole disease. But there is an increasing number of databases emerging resulting from long-term studies conducted over the last decades. These databases finally allow us to determine more specifically whether behavioural symptoms make a difference in dementia disease progression; which behavioural symptoms affect disease progression the most and finally, whether having behavioural symptoms earlier or later in the disease affects the disease progression differently.

Let’s start with the first one. In essence, research has shown that yes behavioural (neuropsychiatric) symptoms affect dementia disease progression. Early studies have shown that in particular agitation and psychosis determine dementia disease progression. Agitation is a highly common symptom in dementia, in particular, in the latter stages of the disease and often presents itself by the person being extremely restless, fidgeting or pacing (walking forth and back without purpose). It can be caused by a variety of reasons, such as pain, discomfort, anxiety, thirst, hunger, the environment (too noisy, too hot, too cold) and also as a side effect of certain medications. Based on the above we can already see that agitation is often related to communication problems since the person with dementia can often not communicate their needs (I am in pain/hungry/thirsty/too cold/too hot) as efficiently as before. The result of this communication breakdown is often agitation which often subsides once the underlying cause of the agitation is identified by the carers. However, if the cause of the agitation is not identified by the carers or healthcare professionals, the agitation can quickly escalate into more serious consequences, such as delirium or psychosis.

Psychosis is an umbrella term describing psychiatric symptoms in dementia, such as hallucinations (seeing or hearing things that are not there) and delusions (unshakable beliefs that are out of context with a person’s social and cultural background, e.g. I am being followed by people or believing that family members are impostors). Psychosis symptoms can be very distressing to the person with dementia and their families and are, thankfully, quite rare for most dementias.

Previous studies suggested that agitation and psychosis might be particularly affecting the disease progression. We come back to the ‘why’ later on. However, more recent studies suggest that behavioural symptoms, in general, might increase the disease progression. Specifically, studies have found that the higher the number of behavioural symptoms the higher the rate of progression in dementia. So, it might not be which behavioural symptoms people with dementia have that determine their disease progression but how many. In essence, the more behavioural symptoms the faster the disease progression.

How about dementias who have behavioural symptoms from the start of the start of the disease?

Are all the dementias the same?

Again, more recent findings have shed light on this question and found that in fact there is a big difference between dementias which have usually few or no behavioural symptoms at the beginning (for example Alzheimer’s disease) versus dementias with often more significant behavioural symptoms at the beginning of the disease (for example frontotemporal dementia). In fact, for non-Alzheimer dementia, there is less of a relationship between the number of behavioural symptoms and the disease progression. In other words, the disease progression does not seem to be influenced as much for these non-Alzheimer dementias by their behavioural changes. The only exception is psychosis symptoms (hallucinations, delusions) which affect non-Alzheimer’s disease progression.

In contrast, for Alzheimer’s disease, the amount of behavioural symptoms makes a significant difference to their disease progression. In particular, a combination of symptoms such as depression, anxiety, apathy, delusions, hallucinations, irritability and motor disturbance seems to be strongest related to faster disease progression.

How would behavioural symptoms affect disease progression, you might ask?

It’s an important question, which is not easy to answer for now. There are three main options:

1) Behavioural symptoms might be a sign that people have more of an aggressive form of dementia. The behavioural symptoms might be then simply in this case a marker for more aggressive disease and hence people have a faster disease progression. But the mechanism of how behavioural symptoms might cause a more aggressive disease is completely unclear and so for now this remains pure speculation. The second option seems more plausible.

2) Behavioural symptoms might result in less optimal dementia care for people with significant behavioural symptoms. Behavioural symptoms are known to cause significant distress and burden for dementia carers and this might inadvertently lead to less optimal dementia care. For example, behavioural symptoms may make the person with dementia less willing to engage in care activities. Just imagine having to care for a person who is highly agitated and the challenge becomes very clear. But still, maybe behavioural symptoms leads to less optimal care in some people with dementia but not everyone, so this factor might only explain part of it.

3) Finally, clinicians often prescribe antipsychotic medication for severe behavioural symptoms. Antipsychotic medication has been shown to lead to a decline in cognition and therefore a potentially faster disease progression. Most clinicians are aware of these risk and have to make the careful decision whether antipsychotic medication is the best treatment option for a person with behavioural symptoms. As with any medication it is about weighing the benefits and risks of giving that medication. Antipsychotic medication prescription might also explain why earlier studies have found that agitation or psychosis lead to faster disease progression since those symptoms can often lead to antipsychotic medication prescription. It would also explain why non-Alzheimer’s disease who have more psychosis symptoms seem to progress faster.

I am afraid there is no satisfactory answer to the factors how behavioural symptoms affect disease progression and there is a clear need for future research to investigate this further.

Where does this leave us?

It might seem scary that behavioural symptoms can lead to a faster disease progression but, in my opinion, it is always better to be informed of potential risk which in turn allows being more proactive than reactive. Since we know now that behavioural symptoms can influence the disease progression, once they occur we should consult with specalist healthcare professionals as to what the best way is to maintain the standard of care, despite the behavioural challenges. There are excellent guidelines out there by healthcare professional how to deal with behavioural symptoms and maintain the best care possible in those circumstances. It is also worth discussing the pharmacological treatment options with your clinician. Carefully monitored antipsychotic medication can ameliorate behavioural symptoms while having little effect on disease progression. A good clinician will know that there is a careful balance to strike with behavioural symptoms and antipsychotic medication.

Summary

Behavioural symptoms can affect disease progression. Earlier studies suggested that agitation and psychosis lead to faster disease progression. However, it is not clear whether the use of antipsychotic medication might have affected those results. More recently, it has emerged that the number of behavioural symptoms is far more critical to affecting dementia disease progression, with a higher number of behavioural symptoms being related to a faster disease progression, in particular for Alzheimer’s disease. Specifically, a combination of symptoms such as depression, anxiety, apathy, delusions, hallucinations, irritability and motor disturbance seems to be strongest related to increased disease progression in Alzheimer’s disease. For other dementias which often show behavioural symptoms from the beginning of the disease, behavioural symptoms seem to have less of an effect on disease progression. The reasons why behavioural symptoms affect disease progression remain unclear for now. There have been speculations that the behavioural symptoms are a sign of a more aggressive disease progression with no scientific evidence for that yet. Alternatively, behavioural symptoms might lead to less optimal care, since the person with dementia might engage less or even actively resists care activities. Finally, antipsychotic medication can potentially increase disease progression, if not carefully monitored. Making ourselves aware of behavioural symptoms in dementia and how to manage them, is therefore a first good step to allow us to manage those symptoms which in turn might even affect the disease progression of the person with dementia.

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Links:

• https://www.alzheimers.org.uk/about-dementia/symptoms-and-diagnosis/symptoms/behaviour-changes
• https://www.alzheimers.org.uk/about-dementia/symptoms-and-diagnosis/apathy-depression-anxiety

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