Dementia with Lewy bodies is unique because not only is cognition affected, which happens with other types of dementia, but movement and autonomic processes (key involuntary functions such as breathing, heart rate, digestive processes and body temperature) are also affected.
In addition cognitive symptoms, such as hallucinations and problems with visual perception, appear early in the progression of the disease whereas with Alzheimer’s, for example, the same symptoms do not appear until later.
Because these very challenging symptoms occur in the earlier stages of the disease, the loss of independence occurs much sooner, which has a significant impact on both the person living with dementia and their caregivers.
There are few approved drugs available for the treatment of dementia with Lewy bodies, limited evidence about what treatments work and everyone responds differently. Another problem is that medication prescribed to improve cognition or hallucinations can make movement problems worse and vice/versa. Also people with dementia with Lewy bodies may have a severe reaction to antipsychotic drugs (sometimes fatally) which are often used to treat hallucinations, a common feature of the disease.
I firmly believe that to be able to provide adequate care and support for someone with Lewy body dementia; you have to understand the disease. So I will be updating this post regularly.
Lewy body diseases are a group of conditions caused by deposits of an abnormal protein called Lewy bodies (named after Friedrich H. Lewy, the doctor who first identified them) inside brain cells.
There are 3 types of Lewy body diseases:
Parkinson disease – The main symptoms of Parkinson’s are tremor, rigidity and slowness of movement.
Dementia with Lewy bodies – Symptoms include changes in thinking and reasoning, fluctuating cognition, balance problems and muscle rigidity, visual hallucinations, delusions, trouble interpreting visual information, sleep disorders, malfunctions of the autonomic nervous system and memory loss (but less prominent than in Alzheimer’s).
Parkinson’s disease dementia – Symptoms include changes in memory, concentration and judgement, trouble interpreting visual information, muffled speech, visual hallucinations, delusions, depression and sleep disturbances.
Diagnosing Dementia With Lewy Bodies
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.