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Lewy Body Dementia Facts
- Over 1.4 million Americans are living with Lewy body dementia
- LBD is the 2nd most common progressive dementia after Alzheimer’s disease.
- Lewy body dementia (LBD) is a brain disorder that gradually worsens. It occurs when abnormal buildup of a protein called alpha-synuclein, or Lewy bodies, forms in areas of the brain that control thinking, movement, behavior, and sleep.
- Symptoms often fluctuate— meaning that a person’s alertness and thinking may vary a lot from one hour or a day to the next.
- LBD has similarities with Parkinson’s disease, Alzheimer’s disease, and some psychiatric conditions, which makes early diagnosis difficult.
Brain Changes in Lewy Body Dementia
In LBD, clumps of a protein called alpha-synuclein collect in several areas of the brain, such as:
- Cortex, the outer part of the brain which affects thinking, perception, and behavior
- Brainstem, lower part of the brain which helps control the sleep, blood pressure and other autonomic body functions.
- Limbic areas, the parts of the brain that manage emotions and help form memories.
- The basal ganglia are deep structures in the brain that help control movement. Problems here can lead to parkinsonism.
Some people with LBD also have changes seen in Alzheimer’s disease, like amyloid plaques and tau tangles, which can make thinking problems worse.
Clinical Features of Lewy Body Dementia
LBD affects multiple systems in the body. Symptoms fall into few key areas:
1. Movement Disorders
Many people with LBD show Parkinsonian features, such as:
- Slowness of movement (bradykinesia)
- Muscle stiffness (rigidity)
- Tremor, sometimes less prominent or different than in Parkinson’s disease
- Shuffling gait or balance problems, leading to falls
- Reduced facial expression
These symptoms happen because Lewy bodies damage parts of the brain that control movement.
2. Cognitive Changes
Cognitive symptoms in LBD can look similar to those in Alzheimer’s disease, but there are important differences:
- Fluctuating attention and alertness, sometimes hour to hour
- Early problems with planning, organization, and decision-making
- Difficulty with visual and spatial tasks, such as judging distance
- Slowed thinking
- Memory problems, though often less severe early in the illness
3. Behavioral and Psychiatric Changes
LBD frequently causes:
- Visual hallucinations, often vivid and well-formed
- Delusions or false belief
- Depression and anxiety
- Apathy or reduced motivation
- People with LBD may be sensitive to some psychiatric medications, which can make movement or thinking problems worse
4. Sleep-Related Features
Sleep problems are very common in LBD and can show up years before memory issues begin:
- REM Sleep Behavior Disorder (RBD) means physically acting out dreams, such as talking, yelling, or punching. This is a strong sign of synuclein-related diseases.
- Excessive daytime sleepiness
- Insomnia or restless sleep
- A history of RBD or dream-enacting behavior is one of the main findings doctors look for when diagnosing LBD. However, not everyone has this symptom.
5. Autonomic Dysfunction
Lewy bodies can also damage the autonomic nervous system, which controls automatic body functions. This can lead to:
- Orthostatic hypotension (drop in blood pressure when standing)
- Constipation
- Urinary urgency, frequency, or incontinence
- Difficulty with erection
- Temperature regulation problems
- Drooling or swallowing difficulties
These symptoms can have a big impact on daily life and often need specific treatment.
Types of Lewy Body Dementia
There are two main types of LBD that doctors diagnose:
1. Dementia with Lewy Bodies (DLB)
- Cognitive symptoms (especially fluctuations, hallucinations, and attention problems) appear first or within one year of motor symptoms.
- Movement symptoms may be mild early on.
2. Parkinson’s Disease Dementia (PDD)
- Parkinsonian motor symptoms begin years before cognitive decline.
- If dementia starts more than a year after Parkinson’s movement symptoms begin, it is called PDD.
Both conditions are caused by the same problem: the buildup of Lewy bodies in the brain.
Risk Factors
Doctors do not know the exact cause of LBD, but some risk factors include:
- Age (typically > 60 years)
- Male sex (which carries a slightly higher risk)
- Having REM Sleep Behavior Disorder, or acting out dreams, which is a major predictor
- A family history of Parkinson’s disease or LBD
- Certain gene variants, like GBA and SNCA, though most cases are not strongly inherited
- Possible environmental factors, but these have not been firmly proven
How Lewy Body Dementia Is Diagnosed
Doctors diagnose LBD based on symptoms, but special tests can help. According to international guidelines, the main features doctors look for are:
- Fluctuating cognition
- Recurrent visual hallucinations
- REM Sleep Behavior Disorder
- Parkinsonism
Because LBD symptoms are similar to other conditions, doctors may use extra tests to be more certain about the diagnosis.
DATscan (Dopamine Transporter Imaging)
- This scan measures the amount of dopamine transporter activity in the basal ganglia, which is the part of the brain that helps control movement.
- People with LBD usually have reduced uptake, which is also seen in Parkinson’s disease.
- This scan helps tell LBD apart from Alzheimer’s disease, since Alzheimer’s usually shows normal uptake.
- It is helpful when motor symptoms are mild or not clearly defined.
Cerebrospinal Fluid (CSF) Analysis
CSF biomarkers can help differentiate LBD from other dementias:
- Alzheimer’s markers (amyloid-β, tau) may be normal or only mildly abnormal in LBD.
- Synuclein biomarkers can be detected in the cerebrospinal fluid but not yet widely available.
Skin Biopsy for Alpha-Synuclein
A newer diagnostic tool increasingly used in specialty centers:
- Small skin samples are taken from the neck, thigh, or leg.
- Laboratory analysis detects abnormal phosphorylated alpha-synuclein in peripheral nerves.
- Can support the diagnosis in unclear cases.
