Some forms of rare dementia can be very difficult to diagnose, not only because they are rare but also because their symptoms are not as ‘clear cut’ and overlap with other neurodegenerative diseases. Dementia with Lewy Bodies is such a rare dementia since it can present with highly variable symptoms and its symptoms overlap with another major neurodegenerative condition – Parkinson’s disease. What is Dementia with Lewy Bodies? And how does it overlap and differ from Parkinson’s disease?
Let’s find out.
Dementia with Lewy Bodies, also sometimes referred to as Lewy Body Dementia (just to confuse us all a little bit more), is a rare form of dementia, affecting ~5% (1 in 20) dementia cases worldwide. However, there is a recognition that Dementia with Lewy Bodies is likely underdiagnosed as the symptoms can overlap not only with Parkinsonian disorders, such as Parkinson’s disease but also Alzheimer’s disease. Indeed, there have been suggestions that a significant proportion of clinically diagnosed people with Alzheimer’s disease, might actually have underlying Dementia with Lewy Bodies pathology in their brain. This already makes clear that the clinical diagnosis of Dementia with Lewy Bodies is not straightforward and requires often specialist input.
Why is that?
The main reason is that a definite diagnosis of Dementia with Lewy Bodies is only available at post-mortem, by identifying Lewy Bodies in the brain of the people with the disease. The clinical symptoms are more tricky to identify and can overlap with other conditions.
What are then these ‘Lewy Bodies’?
Lewy Bodies are named after Friedrich (Frederic) Lewy (1885-1950), a German neurologist who made the discovery of the Lewy Bodies during his time in Alois Alzheimer’s laboratory in Munich. Similar to Alzheimer, Lewy did not name his discovery after himself or saw the recognition for his discovery, in fact, Lewy never associated Lewy Bodies with dementia, instead, he identified Lewy Bodies as a potential cause for Parkinson’s disease. Parkinson’s disease, named after the English physician James Parkinson (1755-1824), was clinically well described by the time Lewy investigated it, however, it was not clear what changes in the brain cause Parkinson’s disease. It was Lewy who discovered that one region in the brain of Parkinson’s disease (the substantia nigra; from Latin meaning ‘black substance’ as it refers to a black region in our brainstem) had little ‘balls’ of a protein (later discovered to be a protein called alpha-synuclein), which accumulated and might cause the typical symptoms of Parkinson’s disease. His discovery was confirmed later by many who honoured him by naming these alpha-synuclein bodies ‘Lewy Bodies’.
What has that all to do with Dementia with Lewy Bodies?
The link to understand between Parkinson’s disease and Dementia with Lewy Bodies is that they are both caused by Lewy Bodies and hence the accumulation of the protein alpha-synuclein. The main difference between Parkinson’s disease and Dementia with Lewy Bodies is as to where in the brain the Lewy Bodies accumulate. For Parkinson’s disease, the Lewy Bodies accumulate at the beginning of the disease mostly in a very deep brain region – the substantia nigra, causing the typical movement symptoms of Parkinson’s disease. For Dementia with Lewy Bodies, the Lewy Bodies can be found more distributed over the brain. This distribution can differ from individual to individual, which means that also the symptoms can be very variable between people, since the location of the Lewy Bodies determines which nerve cells get impaired and damaged, causing the symptoms.
So, what are then the ‘typical’ clinical symptoms of Dementia with Lewy Bodies?
There has been for a long time confusion as to which clinical symptoms are ‘typical’ for Dementia with Lewy Bodies, however, in 2017 an international expert commission published revised diagnostic criteria, which has greatly improved the clinical characterisation of Dementia with Lewy Bodies. The commission came up with four core clinical features for a diagnosis of ‘probable Dementia with Lewy Bodies’ (let’s remember that a diagnosis of ‘definite Dementia with Lewy Bodies’ can only be given at post-mortem by checking the brain for Lewy Bodies):
Fluctuating cognition, attention and alertness
The first core clinical symptom is that changes in cognition, attention and alertness can fluctuate widely in Dementia with Lewy Bodies. Most people with dementia would say that they are having good and bad days with their cognition, but for Dementia with Lewy Bodies, these fluctuations are much more extreme and can even change from hour to hour. Cognition and behaviour symptoms in Dementia with Lewy Bodies can be seen therefore often as ‘waxing and waning’. In terms of cognition, memory remains usually intact in Dementia with Lewy Bodies as the hippocampus (the main brain region for memory generation and recall) remains intact. However, people with Dementia Lewy Bodies often show significant changes to their attention, being often very distractable and having difficulties focusing on tasks, which can indirectly affect their memory as well (How can you remember something when you have difficulties focusing on information to retain?). In the worst cases, this can lead to ‘zoning out’ and staring into space for prolonged periods. The other cognitive symptom is incoherent speech, which can be either present as difficulty getting the words out (dysarthria) or so-called ‘word salad’ where the ordering of the words does not make sense. Finally, the fluctuation in alertness can result in people being very drowsy during the daytime, being lethargic or staring into space for long periods. Just to emphasise again that these fluctuations in Dementia with Lewy Bodies are more extreme than in other dementia, which is the main distinction from those dementias.
Far more specific for Dementia with Lewy Bodies are visual hallucinations which occur in 80% (8 out of 10) cases. Visual hallucinations are very rare in other dementias, at least at the beginning of the diseases, so these symptoms are quite specific for Dementia with Lewy Bodies. The other characteristic for hallucinations in Dementia with Lewy Bodies is that they are highly specific or ‘real’. People report ‘seeing’ people, children or animals moving in their main field of vision – not just seeing a shadow move in their peripheral vision. These are highly detailed hallucinations so that people with Lewy Body Dementia can describe in detail what these people/animals are doing as well as their physical characteristics. I remember Dementia with Lewy Body people describing the most vivid hallucinations to me – often to the astonishment of their families, as the families were not aware that the person was ‘seeing’ all this. It highlights that people often do not share such hallucinations with their carers/families, since it can be embarrassing to admit to these and people often think that ‘they are going mad’. But that is not the case, it is simply the visual system in our brain misfunctioning due to the Lewy Bodies. However, for some people, the hallucinations can become very distressing as they are starting to interfere with their lives. For example, I remember seeing one person with Dementia with Lewy Bodies who described to me that in the evenings they often could only watch TV in his living room while sitting on the floor, since the sofa and chairs in the room were already taken by ‘people’ sitting on them. They also had to say goodnight to those ‘people’ before going to bed, as they would otherwise admonish them the next day. This might at first appear quite comical, imagining the person sitting on the floor in an empty room while watching TV before saying goodnight to the same empty room, however, it was clearly distressing to them. If such visual hallucinations become distressing, then one should always talk to the doctor to discuss potential treatment options for hallucinations.
The next core clinical feature of Dementia with Lewy Bodies is Parkinsonism. Parkinsonism in this context means symptoms similar to Parkinson’s disease. These symptoms are mostly focused around movement problems, with the key symptoms being bradykinesia (from Ancient Greek ‘brady’ = slow; ‘kinesia’ = movement; meaning slow movements) in combination with rest tremor (shaking of hands/feet at rest) and rigidity (stiffness of muscles). However, for many Dementia with Lewy Body people, these symptoms are less pronounced than in Parkinson’s disease and can be harder to spot. It is also often the case that in Dementia with Lewy Bodies, people have only one of these Parkinsonian symptoms (bradykinesia, rest tremor, rigidity) but not 2 or 3 of them, as it is the case in Parkinson’s disease. Often only a specialist might spot or detect these Parkinsonian symptoms in Dementia with Lewy Bodies, while they are far more obvious in Parkinson’s disease. The other caveat is that one needs to be careful not to ‘misdiagnose’ other age-related diseases the person might have, such as arthritis or frailty, which can affect movements and mimic Parkinsonism.
REM sleep disorder behaviour
The last core symptom of Dementia with Lewy Bodies, REM sleep disorder behaviour, is also its recent recognised core symptom but has emerged as maybe its most specific one. Now, the terminology is a bit complicated, so let’s unpack it. ‘Sleep disorder behaviour’ refers to ‘unusual’ behaviour people display during their sleep. The ‘REM’ term requires a bit more explanation. REM stands for ‘Rapid Eye Movements’ and refers to our REM sleep stage. Our sleep has 4 different sleep stages, through which we cycle several times per night. The last of the 4 sleep stages is the REM sleep stage and it is during REM sleep that we dream. The world of dreams can range from wonderful to horrifying – how many chasing dreams can one have in a lifetime? Since dreams are very vivid to us, we might potentially ‘act our dreams’ out, which could have dangerous consequences since we could hurt ourselves or our sleeping partners. To protect us from such ‘acting out of dreams’, our brain inhibits the activity of all our muscles during REM sleep – except for the muscles which move our eyes. If we would observe someone who is in REM sleep, we can observe that their body is completely relaxed, except for their eyeballs, which are moving rapidly under their closed eyelids – given the REM sleep stage its name. Anyone, who has seen a dog sleeping and dreaming can check that their eyeballs are also moving in fast, jerky movement under their closed eyelids, while the rest of their body is relaxed – except for the occasional twitchy paw and muffled bark, indicating that even dogs have chasing dreams! Before we diverge into Freudian dream interpretation, let’s re-cap that during REM sleep we dream and that our whole body is relaxed except for our eyeballs which are moving jerkily and fast under our closed eyeballs. Now, remember that our relaxed muscles are to protect us to ‘act out our dreams’? This relaxation of our muscles during REM sleep fails – for unknown reasons yet – in Dementia with Lewy Bodies. It results in Dementia with Lewy Body people ‘acting out their dreams’ on a regular basis. Before you get scared that you might have Dementia with Lewy Bodies, let me reassure you that everyone acts out once in a while their dream or wakes up screaming. That is completely normal, however, this ‘acting out of dreams’ is a very common occurrence in Dementia with Lewy Bodies, in some cases a daily occurrence. This is not trivial, as people can inadvertently injure themselves and others when acting out dreams. Just imagine acting out those horrible dreams and indeed, carers regularly report that the person with Dementia with Lewy Bodies gets up, walks/runs/jumps around and even sometimes attacks or strangles them. Clearly not an easy situation for the carer and at the least highly embarrassing for the person with Dementia with Lewy Bodies. It is still not understood how such ‘acting out of dreams’ is caused in Dementia with Lewy Bodies but it has over the last years emerged that it is a very specific symptom for Dementia with Lewy Bodies and can occur years before any of the cognitive or movement symptoms emerge. It remains therefore an interesting question as to whether screening for Dementia with Lewy Bodies should be conducted more at Sleep clinics since many people will visit those long before their cognition, behaviour and movements change.
So, there we have it, the key clinical symptoms for Dementia with Lewy Bodies are fluctuating cognition, behaviour and alertness, visual hallucinations, Parkinsonism and REM sleep disorder behaviour. But there are also many other ‘supportive symptoms’ in Dementia with Lewy Bodies, which affect a smaller percentage of people. For example, some people will have changes to their smell or the autonomous nervous system. The autonomous nervous system regulates not only our sleep but also many of our internal organs, from digestion to sweating. Dementia with Lewy Bodies can cause therefore as well symptoms such as constipation or excessive sweating but these symptoms are very variable across people, with some having none of these while for others these might be quite severe. The final supportive symptom can be other psychiatric symptoms, in addition to hallucinations, such as delusions. Delusions are defined as unusual beliefs or impressions which are maintained even when they are not supported by reality or rational argument. For example, people will have the impression that they are constantly followed or watched, despite their being no evidence for this. It can be a very disturbing symptom to the person and their carer and families but is, thankfully, rarer in Dementia with Lewy Bodies.
How about the overlap between Dementia with Lewy Bodies and Parkinson’s disease dementia?
The reason why there can be confusion as to whether someone has Dementia with Lewy Bodies or Parkinson’s disease stems from the fact that many people with Parkinson’s disease develop cognitive symptoms or even dementia in the latter stages of their disease. This can make Dementia with Lewy Bodies and Parkinson’s disease dementia appear very similar since both have movement and cognitive symptoms (Parkinson’s people can also have some of the ‘core symptoms’ for Dementia with Lewy Bodies, such as hallucinations and sleep changes).
How can one distinguish then the two from each other?
Like so many things in life, it’s all about timing. The key to understanding the difference is to consider the timing for Parkinsonism and cognitive symptoms. For Dementia with Lewy Bodies it is mostly the cognitive changes that are noticed first and the movement (Parkinsonism) symptoms are quite mild, whereas for Parkinson’s disease with Dementia it is the movement (Parkinsonism) symptoms that occur first before the cognitive symptoms emerge. The main reason for this is that for Dementia with Lewy Bodies, the Lewy Bodies are more affecting the cognitive regions of the brain at the beginning while for Parkinson’s disease the Lewy Bodies are more affecting the movement regions deep in the brain (substantial nigra) at the beginning of the disease.
If Dementia with Lewy Bodies and Parkinson’s disease are caused both by Lewy Bodies can we potentially use then same medication for both of them?
This is an interesting question, since their are existing medications for treating Parkinson’s disease. Most of these medications boost a neurotransmitter (Dopamine) which becomes depleted in Parkinson’s disease due to the Lewy Bodies in the substantia nigra (the deep brain region responsible for our movements). Now, there is evidence that dopamine boosting medication can also improve some movement symptoms in Dementia with Lewy Bodies, however the movement problems are usually much milder in Dementia with Lewy Bodies and hence the medication has less of an impact. On the contrary, the dopamine boosting medication can actually cause more visual hallucinations in Dementia with Lewy Bodies and clinicians are – understandably – very cautious when starting people with Dementia with Lewy Bodies on this medication. It clearly is a dilemma would one improve one symptom (movement) while worsening another (hallucinations).
Could one not just treat the hallucinations at the same time?
That is a very tricky question since it is known that Dementia with Lewy Bodies people have often severe adverse reactions to neuroleptic medication, commonly used to treat hallucinations or other psychiatric symptoms. In fact, studies have shown that neuroleptic administration in Dementia with Lewy Bodies to treat hallucinations increases the risk of mortality by up to 3-fold. It is a classic case of ‘curing a symptom by killing the patient’, which clearly no one wants. However, often clinicians are ‘between a rock and a hard place’/dilemma as the hallucinations are so disturbing to people with Dementia with Lewy Bodies that neuroleptics are the only way to treat it. In that case, there needs to be a careful discussion as to whether non-pharmacological treatments can potentially alleviate the symptoms or whether it is worth trying neuroleptics. It highlights that the management of Dementia with Lewy Bodies symptoms is complex for carers, healthcare professionals and clinicians and often requires a multi-disciplinary approach as one not only deals with cognitive and movement changes but often severe sleep disturbances and hallucinations.
I strongly recommend an article written by the wife of the late actor Robin Williams. Click here for the link. Robin Williams was diagnosed with Dementia with Lewy Bodies at post-mortem. His wife Susan describes in the article very honestly their quest for a diagnosis and all the symptoms he had over the preceding years. In fact, Robin William never received a clinical diagnosis of Dementia with Lewy Bodies during his lifetime, instead, he was diagnosed with Parkinson’s disease (there were also suggestions of Alzheimer’s disease or even Schizophrenia, due to his psychiatric symptoms). Only after his suicide, the post-mortem ‘discovered’ the Lewy Bodies in the brain and all the symptoms made suddenly sense. It is a very brave account of his wife to be so honest about their journey with the disease and shows also that someone who has access to any possible specialist might not receive a diagnosis during their lifetime. I strongly recommend reading her account, as it should ‘bring to life’ all the symptoms described in the previous sections.
In summary, Dementia with Lewy Bodies is a rare form of dementia that overlaps with Parkinson’s disease. Both, Dementia with Lewy Bodies and Parkinson’s disease are caused by Lewy Bodies (the accumulation of a protein called alpha-synuclein). However, for Dementia with Lewy Bodies movement symptoms are often milder than in Parkinson’s disease, as the Lewy Bodies are more distributed across the superficial brain regions, whereas in Parkinson’s disease they are mostly located in deeper brain regions responsible for movement. In addition, Dementia with Lewy Bodies people have often significantly fluctuating cognition, behaviour and alertness symptoms. This is complemented by vivid and complex visual hallucinations and sleep disturbances, which present as ‘acting out dreams’. Medication for Dementia with Lewy Bodies is complex, as medication for Parkinson’s disease can cause more hallucinations, which are difficult to treat since people can have severe reactions to neuroleptic medication. Dementia with Lewy Bodies is a complex disease requiring a multi-disciplinary approach. This further underlines, that people need to be made more aware of the complexity of Dementia with Lewy Bodies, to support and care as best as possible people with Dementia with Lewy Bodies, their carers and families.
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