About Dementia with Lewy Bodies

Aug 9, 2021

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About Dementia with Lewy Bodies

About Dementia with Lewy Bodies

Posted in : Diagnosis on by : Catherine Verner

Dementia with Lewy Body (DLB) is a type of dementia, accounting for about 10-15% of all dementia cases. It affects approximately 100,000 people in the UK and over one million people in the USA. Dementia with Lewy body has a few names, all referring to this same condition. This includes Lewy body dementia, Lewy body variant of Alzheimer’s disease, diffuse Lewy body disease and cortical Lewy body disease.

In this article we look to provide an introduction to dementia with Lewy bodies by answering the following questions:

  • What is dementia with Lewy bodies?
  • What causes it?
  • What are the symptoms?
  • What are the different types of dementia with Lewy bodies?
  • How is dementia with Lewy bodies diagnosed and treated? 

What is dementia with Lewy Bodies?

Lewy bodies are named after Dr. Friederich Heinrich Lewy, a German-born neurologist who, in 1912, discovered abnormal protein deposits in the brain while researching Parkinson’s disease.  These abnormal deposits are known as “Lewy bodies”.  

Lewy bodies are tiny particles of protein that deposit in the brain, disrupting normal brain functioning. Scientists are not sure whether the Lewy bodies are the cause or the effect of cell death in the brain. However, what they do know is that Lewy bodies are thought to be the result of the misfolding of a protein called alpha-synuclein. 

Lewy bodies occur in specific areas of the brain. They lead to the eventual death of brain cells and cause symptoms of dementia which include changes in movement, thinking, and behaviour. For this reason, this form of dementia is called dementia with Lewy bodies (DLB). 

What are the causes?

Our brain contains billions of neurons (or nerve cells) that transmit or receive signals. These signals are transported across small gaps called synapses between neurons. This is done by neurotransmitters (the body’s chemical messengers).  A protein called alpha-synuclein regulates this trafficking and neurotransmitter release.  In dementia with Lewy bodies, clumps of alpha-synuclein form inside brain cells.  This abnormal accumulation of protein results in the neurons working less effectively and eventually dying.  Over time, this leads to increased damage to specific areas in the brain. This in turn leads to a decline in abilities associated with those brain regions:

  • The cerebral cortex involves planning and organisation, language, processing sensory information, and motor function.  
  • The limbic cortex, responsible for our behavioural and emotional responses.
  • The hippocampus, essential for forming new memories
  • The midbrain and basal ganglia, involved in our motor control
  • The brain stem, linked with regulating sleep, eating, breathing, and maintaining alertness
  • Olfactory pathways, important in recognising smells.

As you can see, a number of different areas of the brain can be affected. People with a diagnosis of dementia with Lewy bodies will have a combination of cognitive (Alzheimer’s) and motor (Parkinson’s) symptoms at the same time.  

What are the symptoms?

As in other forms of dementia, each person’s experience is unique. Different people will show a different range of symptoms, associated both Alzheimer’s cognitive symptoms and Parkinson’s disease movement disabilities. The core symptoms associated with dementia with Lewy bodies are:

  • Fluctuating states of consciousness

It can be common for people with dementia with Lewy bodies to have extreme swings from alertness to confusion.  These can occur unexpectedly from minutes to days. 

  • Visual hallucinations

Many people with dementia with Lewy bodies experience vivid visual hallucinations.  These can range from pleasant visions to extremely frightening and distressing hallucinations.  

  • Spontaneous Parkinsonism

People with a diagnosis of dementia with Lewy bodies experience motor difficulties seen in Parkinson’s disease.  These symptoms include slow movement when walking, stiffness, or falls. Less common, however, are the tremors associated with Parkinson’s disease.  Other symptoms could include difficulty with balance and facial impassiveness.  In both disorders, the person may suffer from autonomic symptoms such as a sudden drop in blood pressure upon standing, difficulty swallowing, incontinence, or constipation. 

  • Disturbances in REM sleep

REM (rapid eye movement) sleep is a deep state of sleep that we go into when dreaming.  REM sleep is also thought to aid memory.  Often people with dementia with Lewy bodies struggle with disturbed REM sleep. During this stage of sleep, the person may talk in their sleep or act out their dreams. 

Symptoms in early-stage dementia with Lewy bodies can be mild, and people can still function fairly well.  However, as the condition progresses, these symptoms can worsen and disrupt everyday life and activities. Each person will experience different degrees and combinations of symptoms.

Here we share Themiya’s story about her father, who has dementia with Lewy bodies:

What are the different types of dementia with Lewy bodies?

Lewy body disease includes three disorders:

  • Dementia with Lewy bodies
  • Parkinson’s disease
  • Parkinson’s disease dementia

As this suggests, Lewy bodies are present in the brains of people with dementia with Lewy bodies and Parkinson’s disease. Although both conditions develop similar symptoms, they differ in the timing of the onset of cognitive symptoms.  

What are the risk factors?

The gene variants associated with Alzheimer’s disease (APOE) and Parkinson’s disease (GBA, SNCA) are also associated with dementia with Lewy bodies. This is not surprising as the symptoms of Alzheimer’s disease and Parkinson’s disease are also present in dementia with Lewy bodies.  For more general information on risk factors associated with dementia, check out our article “Risk factors for dementia.”

How is it diagnosed?

Dementia with Lewy bodies can often be challenging to diagnose because it shares cognitive symptoms associated with Alzheimer’s disease and motor symptoms associated with Parkinson’s disease.  Therefore, it can sometimes result in a misdiagnosis. In addition, symptoms of dementia with Lewy bodies can vary significantly over time.  However, a holistic and thorough clinical examination can result in a confident diagnosis. 

The doctor will carry out mental ability tests and a neurological examination (including such checks as reflexes, stiffness, and balance). The doctor may also look for varying levels of attention or alertness, visual hallucinations, motor problems, and sleep disturbance.

If further investigation is required, brain scans may be used to help decide on the diagnosis. Computed tomography (CT) or magnetic resonance imaging (MRI) can help rule out other conditions such as a brain tumour with similar symptoms. It can also rule out whether or not a person has dementia with Lewy bodies as opposed to vascular dementia.

What treatments are available?

There is no cure for dementia with Lewy bodies. However, there is medication that can help alleviate the symptoms:

Medications such as donepezil (Aricept), rivastigmine (Exelon), and galantine (Reminyl) may help improve hallucinations, sleepiness and confusion.  These types of medication are known as acetylcholinesterase inhibitors. They help by increasing the levels of acetylcholine in the brain, a chemical that improves neurotransmission in the brain (the sending of signals between brain cells). 

Memantine is used for moderate to severe dementia with Lewy bodies. It works by blocking a chemical in the brain called glutamate. It decreases abnormal activity in the brain and can help improve cognitive function.

Other medicines that may help control some symptoms of dementia with Lewy bodies include:

  • Levodopa can help with problems with movement.  However, this medication needs to be carefully monitored by a physician as in some people; it can worsen symptoms.
  • If depression is suspected, the doctor may prescribe antidepressants.
  • Clonazepam may be prescribed to help with REM (rapid eye movement) sleep behaviour disorder.
  • Neuroleptic (Antipsychotics) drugs such as haloperidol may help alleviate the symptoms associated with hallucinations and agitation or if the person’s behaviour puts themselves or others safety at risk. However, this requires careful monitoring as it can cause people to have severe adverse reactions.

In addition to medication, to help with symptoms associated with Parkinson’s disease, therapies such as occupational therapy to help with personal care such as getting dressed, speech therapy to help with swallowing, and physiotherapy to help with movement can also help.  

If you or someone close to you have symptoms of dementia with Lewy bodies, have a look at our articles in our diagnosis series: 

References

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