Many people will have never heard of behavioural variant frontotemporal dementia but it is, in my opinion, one of the most devastating dementias. The reason for its devastating status is that this type of dementia changes people’s personality and behaviour drastically. Most of us will be familiar with behavioural symptoms in dementia, which for many dementias occur only later in the disease and are often more related to triggers in the environment. Not so for behavioural variant frontotemporal dementia, where these behavioural and personality changes are an integral part of the disease, right from its onset.
Let’s explore this rare type of dementia to understand better which symptoms are associated with it, how these symptoms are caused and what impact they have on their carers and families.
What is behavioural variant frontotemporal dementia?
Behavioural variant frontotemporal dementia (abbreviated ‘bvFTD’ ) is a clinical subtype of frontotemporal dementia (FTD) and belongs, therefore, to the young-onset dementias (young-onset means that this type of dementia is more common in people under the age of 65). Frontotemporal dementia is an umbrella term, similar to dementia, encompassing three clinical subtypes of frontotemporal dementia: 1) Behavioural variant frontotemporal dementia; 2) semantic variant primary progressive aphasia (formerly called semantic dementia); and 3) nonfluent variant primary progressive aphasia. I know these are very long and complex names but the following will solely focus on behavioural variant frontotemporal dementia and I will cover the other clinical subtypes of frontotemporal dementia (semantic variant primary progressive aphasia, nonfluent variant primary progressive aphasia) in future parts of my Rare Dementia Series. For now, we just need to be aware that two other subtypes of frontotemporal dementia exist.
Let’s start by unpacking the terminology of ‘behavioural variant frontotemporal dementia’.
The ‘behavioural’ term gives already away that the symptoms we see in behavioural variant frontotemporal dementia are mostly related to changes in the behaviour, which we will explore in more detail further below. ‘Variant’ just tell us that it is one form of frontotemporal dementia. The ‘frontotemporal’ term gives us a clue which brain regions are affected by the disease, namely the frontal and temporal regions (scientifically called ‘lobes’) of our brain. The frontal brain regions are sitting just behind our forehead and eyes and are important for our everyday behaviour, decision-making, planning, language and movements. The temporal brain regions sit a bit lower, behind our temples, and are strongly connected to the frontal brain regions. Have a look at the MRI scan below where I indicated the location of the frontal and temporal brain regions. You might have already heard of the temporal lobe regions in the context of Alzheimer’s disease, which affects the medial temporal lobe regions, including the hippocampus, which is important for our episodic (personally experienced) memory and spatial navigation. However, for frontotemporal dementia, it is not the medial (middle) temporal brain regions that are affected, but instead the anterior (frontal) parts of the temporal brain regions. The anterior temporal brain regions lie just adjacent to the frontal brain regions and are connected with each other via a large bundle of nerves, indicating that both of them work closely together. The anterior temporal brain regions are involved particularly in semantic memory, which is our memory for facts and knowledge of the world. For example, we know the capital city of our country or we know that insects have 6 legs, while spiders have 8 legs.
Now we know that frontotemporal dementia affects two key brain regions, the frontal and temporal brain regions, which are important for our behavioural regulation and semantic memory, respectively. Since those brain regions are affected, we know that in frontotemporal dementia, the main symptoms will affect our behaviour and semantic memory. For the behavioural variant frontotemporal dementia, as the name gives away, the symptoms are mostly focused on these behavioural changes with lesser semantic memory symptoms.
What are then the behavioural changes in behavioural variant frontotemporal dementia?
Before we go through all the behaviour and personality changes in behavioural variant frontotemporal dementia, I want to caution that some of these changes are quite confronting if not offensive. However, if you have ever met someone with behavioural variant frontotemporal dementia you will know that these are true changes. I have myself seen numerous behavioural variant frontotemporal dementia people over the years, as I worked for several years in frontotemporal dementia specialist centres. The described changes are all also all based on the international diagnostic criteria for behavioural variant frontotemporal dementia, so clinicians use the behaviour and personality changes as an indicator for a diagnosis. Finally, people with behavioural variant frontotemporal dementia do not need to have all these symptoms for a diagnosis. It is just a list of common symptoms in behavioural variant frontotemporal and people can have only some of those to receive a diagnose and the severity of symptoms of the symptoms can also vary between people. However, for completeness sake, we will explore all symptoms so that we are all more aware of what changes can be associated with behavioural variant frontotemporal dementia.
The behaviour and personality changes in behavioural variant frontotemporal dementia are categorised as follows: Behavioural disinhibition; Apathy; Loss of sympathy or empathy; Perseverative, Stereotyped or compulsive/ritualistic behaviour; and Hyperorality and dietary changes.
Now, what do these symptoms actually mean?
Let’s start with behavioural disinhibition. Behavioural disinhibition encompasses a large range of symptoms but in essence, it represents behaviour that is ‘out of character’ for that person. In particular, people are less inhibited in social situations often resulting in socially inappropriate behaviour. For example, the person might make crass jokes to people they barely know, which they would never have done before, and to the embarrassment of the family. Another example is that they make rash decision or actions without thought of future consequences. I remember a person with behavioural variant frontotemporal dementia who decided one day to remove all the windows of the house while their partner was away, and couldn’t put them back. It was not clear why the person wanted to remove the windows, they simply thought it was a good idea at the time and acted impulsively on this thought. Such stories are often in retrospect amusing to the families, but at the same time, these ‘out-of-character’ behaviours can be extremely baffling and deeply upsetting.
The next feature ‘apathy’ describes when people lose the motivation to do things they found previously rewarding, such as hobbies. Apathy is very common in many dementias but in behavioural variant frontotemporal dementia apathy can sometimes alternate or oscillate with impulsivity so that the person with behavioural variant frontotemporal dementia is sometimes very active and rash in their actions while at other times they just sit and do not move for a long time. So, apathy in behavioural variant frontotemporal dementia can appear like quite a drastic symptoms as it often contrasts with their rash decisions.
The loss of sympathy or empathy is often the most devastating behavioural changes in behavioural variant frontotemporal dementia, with carers and families often reporting that the person with behavioural variant frontotemporal dementia is ’emotionally cold’ and ‘does not care about us anymore’. Even from the outside, it is often awful to see how the families report that these emotional changes have made them a completely different person, again completely out of character. For example, over the years I have heard many examples when a family member reported that they were involved in a serious accident or developed a serious disease, which did not seem to affect the person with behavioural variant frontotemporal dementia at all, whereas the whole family was severely affected by this occurrence. It is important to highlight that the person with behavioural variant frontotemporal dementia is not wilfully cold but it is again the disease causing this emotional coldness, which changed them from a loving, caring person to someone who is cold and distantiated. It is, in my opinion, just awful and heart-breaking to see.
Next perseveration, which means doing the same thing over and over again. People with behavioural variant frontotemporal dementia often like to do the same actions over and over again, which can lead to nearly compulsive behaviour (they have to do it or otherwise they will get very upset). For example, they might pace a lot within the house or the grounds or might re-sort objects repeatedly. The final behavioural change is more about changes in their dietary behaviour. People with behavioural variant frontotemporal dementia often develop a ‘sweet tooth’. We all like some sweet food from time to time, but people with behavioural variant frontotemporal dementia become often only focused on sweet food, which can lead to the families hiding or not buying sweet foods anymore. The other often reported eating-related change is that they cannot stop eating, as they do not have a feeling of satiety anymore, leading often to a significant weight gain.
How about the person with behavioural variant frontotemporal dementia? Are they not affected by these behaviour and personality changes?
This is one of the most puzzling aspects of behavioural variant frontotemporal dementia, as people with the disease have often no or little insight into their own behaviour and personality changes. I guess we are all somewhat blind to our own personality eccentricities but we should remember that in behavioural variant frontotemporal dementia there is an out of character change in behaviour. If any one of us would change their behaviour drastically, the people around us would be starting to ask what is going on with us. Not so in behavioural variant frontotemporal dementia for which people with the disease are blissfully unaware that anything has changed or is wrong with them, even when displaying highly socially inappropriate behaviour (such as sexual disinhibition). This lack of disease insight, leads often to a delay in diagnosis, as the person with behavioural variant frontotemporal dementia tells the doctor that nothing is wrong with them, while their carer or family report a significant out of character change in behaviour and personality. Often it is only when people are referred to a specialist frontotemporal dementia clinic, that they receive a diagnose and the appropriate support.
How are these behaviour and personality changes caused in behavioural variant frontotemporal dementia?
The reason for these behavioural changes, including the loss of insight, is due to the changes to the frontal brain regions in behavioural variant frontotemporal dementia. It has been known since the 19th century that changes or damage to the frontal brain regions, for example by gunshot wounds or more recently car accidents, can lead to significant changes in people’s behaviour. In behavioural variant frontotemporal dementia it is of course not an injury/accident which causes these behavioural changes but like other dementias the accumulation of proteins leading to eventually to nerve cell death in the frontal brain regions.
The two proteins causing behavioural variant frontotemporal dementia – tau and TDP-43 (abbreviated for ‘Tar binding DNA protein 43’). (There is also a very rare form of behavioural variant frontotemporal dementia caused by another protein – FUS = Fused-in Sarcoma – which I am not covering here). We might remember that tau is also involved in Alzheimer’s disease, however, it is a slightly different version of tau which causes behavioural variant frontotemporal dementia. Half of the people with behavioural variant frontotemporal dementia have tau causing their disease, while the remaining half have TDP-43 causing their disease. Why some people have tau while others have TDP-43 causing behavioural variant frontotemporal dementia is still not clear and is currently being investigated.
But what we know is that the increasing levels of tau and TDP-43 in the frontal brain regions cause the behaviour and personality changes in behavioural variant frontotemporal dementia. This is a very important point, as the behaviour and personality changes are not wilful actions of the person with behavioural variant frontotemporal dementia but it is the proteins accumulating in the frontal brain region nerve cells which cause them. This is an important fact to realise for many carers and families, as they often report when seeing the doctor that the person is just difficult and completely out of character as if they are willfully difficult. However, it is the changes in their frontal brain regions that cause the behavioural and personality changes in behavioural variant frontotemporal dementia.
Regardless, it is a very challenging situation for the carer and the families, as they need to care for someone who is completely different to the person they knew before the disease started and who has no insight into their symptoms and, therefore, does not want to be cared for. It might come, therefore, not as a surprise that research studies have repeatedly shown that carer distress and burden are the highest for behavioural variant frontotemporal dementia across all dementias. Some carers and families even report at the time of diagnosis that they feel that they ‘have lost the person they loved already’ because of the changes to their behaviour. It is a form of anticipatory grief, which is truly awful and heart-breaking to witness.
In my opinion, it is therefore important to raise the profile of behavioural variant frontotemporal dementia to make people, even in the professional dementia community, more aware of this rare but devastating type of dementia. Yes, these behavioural changes are very confronting and upsetting but to care better for people with behavioural variant frontotemporal dementia we need a better understanding of this rare form of dementia. Only then can we truly help people with behavioural variant frontotemporal dementia, their carers and families on their dementia path.
If you want to find out more about behavioural variant frontotemporal dementia, I recommend the following links:
