Currently there is no way to definitively diagnose dementia with Lewy bodies, which can only be done with certainty by a brain autopsy after death. As a result dementia with Lewy bodies is often misdiagnosed.
Previously the key symptoms (clinical features) and bio markers of dementia with Lewy bodies were combined and categorised as either Central, Core, Suggestive or Supportive, to help evaluate whether a person had a probable or possible diagnosis.
However in June 2017, the International Dementia with Lewy Bodies Consortium, published updated diagnostic criteria, which clearly defines the clinical features and diagnostic bio markers (e.g. brain scans to detect biological signs of disease) to help add greater weight to a probable / possible diagnosis – leading the effort was Prof Ian McKeith of Newcastle University and members of the LBDA’s Scientific Advisory Council.
Revised criteria for the clinical diagnosis of probable/possible dementia with Lewy bodies
The key symptoms of dementia with Lewy bodies are categorised as either Central / Core or Supportive.
Central Clinical Feature.
Dementia is required for a diagnosis of dementia with Lewy bodies i.e. a progressive cognitive decline serious enough to interfere with normal daily activities. Unlike in Alzheimer’s disease memory may not be affected in the early stages, but will become more evident as the disease progresses. Instead a person with dementia with Lewy bodies may experience problems with the following cognitive skills from early in the progression of the disease:
- Reasoning and problems solving known as executive function.
- Visuospatial skills.
Core Clinical Features.
- Fluctuating cognition (awareness and concentration).
- Recurrent visual hallucinations, such as seeing shapes, colours, people, or animals that aren’t there.
- REM sleep behaviour disorder, which often presents years before the onset of dementia.
- Parkinsonism, specifically slowed movement, tremor when limbs are at rest and muscle rigidity.
Note: Fluctuating cognition and visual hallucinations detected early in the progression of dementia with Lewy bodies (as is often the case) can help differentiate from Alzheimer’s disease, where they do not tend to appear until the later stages.
In addition REM sleep behaviour disorder is highly associated with Lewy body disorders but not Alzheimer’s disease.
Supportive Clinical Features.
- Severe sensitivity to antipsychotic drugs.
- Postural instability (poor balance).
- Repeated falls.
- Syncope (fainting).
- Autonomic dysfunction e.g. constipation, falls in blood pressure, urinary incontinence.
- Hypersomnia (excessive day time sleeping).
- Hyposmia (reduced ability to smell and to detect odours).
- Other types of hallucinations i.e. auditory.
- Mood changes i.e. apathy, anxiety and depression.
The new criteria includes diagnostic bio markers, which have now been weighted and categorised, to help physicians make a diagnosis of probable / possible dementia with Lewy bodies. The new bio markers are categorised as either Indicative or Supportive as follows:
Indicative Bio markers.
- Reduced dopamine transporter (DaT) uptake in basal ganglia demonstrated by SPECT or PET.
- Abnormal (low uptake) 123iodineMIBG myocardial scintigraphy.
- Polysomnographic confirmation of REM sleep without atonia.
Supportive Bio markers.
- Relative preservation of medial temporal lobe structures on CT/MRI scan.
- Generalized low uptake on SPECT/PET perfusion/metabolism scan with reduced occipital activity +/- the cingulate island sign on FDG-PET imaging.
- Prominent posterior slow wave activity on EEG with periodic fluctuations in the pre-alpha/theta range.
Probable dementia with Lewy bodies can be diagnosed if:
- two or more core clinical features of DLB are present, with or without the presence of indicative bio markers, or
- only one core clinical feature is present, but with one or more indicative bio markers.
Note: Probable DLB should not be diagnosed on the basis of biomarkers alone.
Possible dementia with Lewy bodies can be diagnosed if:
- only one core clinical feature of DLB is present, with no indicative bio marker evidence, or
- one or more indicative bio markers is present but there are no core clinical features.
Reference: McKeith IG, Boeve BF, Dickson DW, et al. Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium. Neurology. 2017 Jul 4;89(1):88-100.
Our struggle to obtain a diagnosis of dementia with Lewy bodies
It took us around 3 years to obtain a diagnosis of dementia for Mum, although originally she was incorrectly diagnosed as having vascular dementia mixed with Alzheimer’s disease. Fortunately Mum was eventually assigned to a consultant psychiatrist who knew a lot about Lewy body dementia and after one visit (during which she exhibited many of the clinical features associated with dementia with Lewy bodies) he changed the diagnosis.
Our struggle to obtain a diagnosis involved many trips to the doctor trying to explain the problem, not helped by Mum who refused to accept there was one!! The doctor was convinced that Mum was suffering from depression. We finally persuaded Mum to take the standard mini mental state examination (MMSE), which she passed further convincing the doctor that depression was the issue.
At the time I had never even heard of dementia with Lewy bodies and I couldn’t understand why Mum functioned so well in some situations i.e. could pass a MMSE test but she couldn’t make a cup of tea. Of course I now understand that memory is often unaffected in the earlier stages of the disease and that people have more trouble with problem solving and performing a sequence of tasks in the correct order.
Throughout her illness Mum suffered from every single one of the clinical features mentioned above and she suffered from REM sleep behaviour disorder for decades before the onset of her dementia. If I had known about dementia with Lewy bodies and the listed clinical features above, I would have been able to persuade the doctor and obtained a correct probable diagnosis much sooner. And had that happened the journey would have been much easier for all of us.
The Lewy Body Dementia Association have created a very useful ‘Diagnostic Symptoms Checklist’ which you can complete and take along to your doctor if you are worried that you or a loved one may have dementia with Lewy bodies.
You can read in more detail in ‘our story’ how we struggled to obtain a correct diagnosis for Mum.