Lewy body dementia (LBD) is a progressive brain disorder that impacts thinking, movement, behavior, and mood. This comprehensive guide explains the basics of LBD, its causes, symptoms, diagnosis, and available support.
LBD is characterized by abnormal deposits of alpha-synuclein protein in the brain, known as Lewy bodies. These deposits disrupt brain chemistry, leading to various neurological and cognitive issues.
Diagnosing LBD can be difficult because its early symptoms often overlap with those of other conditions such as Alzheimer’s disease. Common early symptoms include changes in mood, vision, sleep patterns, and bowel habits. LBD can occur independently or alongside other brain disorders. The onset typically begins after age 50 and appears to affect slightly more men than women.
LBD is a progressive disease, with symptoms gradually worsening over time. The average lifespan after diagnosis is five to seven years, although this can range from two to twenty years. The rate of progression varies depending on factors such as overall health, age, and symptom severity.
Understanding Lewy Bodies
Lewy bodies are named after Dr. Friedrich Lewy, who first discovered these abnormal protein deposits in the brains of individuals with Parkinson’s disease in 1912. These deposits disrupt normal brain function.
In healthy brains, alpha-synuclein plays a crucial role in neuronal function, particularly at synapses. In LBD, alpha-synuclein clumps inside neurons, starting in specific brain regions. This process impairs neuronal function and ultimately leads to cell death. The activity of certain brain chemicals essential for brain function is also affected. This causes widespread damage and a decline in abilities controlled by the affected brain regions.
In LBD, Lewy bodies affect multiple brain regions, including:
- Cerebral cortex: Controls information processing, perception, thought, and language.
- Limbic cortex: Plays a significant role in emotions and behavior.
- Hippocampus: Essential for forming new memories.
- Midbrain and basal ganglia: Involved in movement.
- Brainstem: Important for regulating sleep and maintaining alertness.
- Olfactory pathways: Important for recognizing smells.
The impact of LBD can also extend to nervous system tissues outside the brain, leading to symptoms such as constipation, dizziness, sexual dysfunction, and drooling.
Causes and Risk Factors of Lewy Body Dementia
The exact cause of LBD remains unknown, but researchers are exploring its biology and genetics. They have found that the accumulation of Lewy bodies leads to the loss of neurons that produce important neurotransmitters, such as acetylcholine (for memory and learning) and dopamine (for behavior, cognition, movement, motivation, sleep, and mood).
Known risk factors for LBD include:
- Age: The greatest risk factor, with most cases developing after age 50.
- Sex: Slightly more men are affected.
- Diseases and health conditions: REM sleep behavior disorder and loss of smell are linked to a higher risk.
- Genetics: While family history may increase risk, LBD is not typically hereditary. Certain genetic variants have been found in a small percentage of families with dementia with Lewy bodies.
- Lifestyle: While no specific lifestyle factor has been proven, some studies suggest a healthy lifestyle may reduce the risk of age-associated dementias.
Common Symptoms of Lewy Body Dementia
Symptoms of LBD vary significantly between individuals. It’s important to report any sudden or major changes in functional ability, symptoms, or behavior to a doctor.
Key symptoms include changes in:
- Cognition
- Movement
- Sleep
- Behavior
- Autonomic functions (e.g., blood pressure, bowel control)
Cognitive Symptoms
LBD causes changes in thinking abilities, including:
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Dementia: Loss of cognitive abilities that interferes with daily activities. This includes trouble with attention, visual-spatial abilities, reasoning, and executive functioning. Memory problems may become apparent over time.
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Cognitive fluctuations: Unpredictable changes in concentration, alertness, and wakefulness that can occur daily or throughout the day.
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Hallucinations: Seeing or hearing things that are not present, often realistic visual hallucinations.
Movement Symptoms
Movement problems may not appear for several years in some individuals, while others experience them early. Symptoms may include:
- Slowness of movement
- Muscle rigidity
- Shuffling walk
- Tremor
- Balance problems and falls
- Stooped posture
- Loss of coordination
- Smaller handwriting
- Reduced facial expression
- Difficulty swallowing
- Weak voice
Sleep Disorders
Common sleep disorders in LBD include:
- REM sleep behavior disorder: Acting out dreams, often involving violent movements.
- Excessive daytime sleepiness: Sleeping for two or more hours during the day.
- Insomnia: Difficulty falling or staying asleep.
- Restless leg syndrome: An urge to move the legs to relieve unpleasant sensations.
Behavioral and Mood Symptoms
Changes in behavior and mood can include:
- Depression: Persistent sadness or loss of interest.
- Apathy: Lack of interest in activities.
- Anxiety: Intense fear or uncertainty.
- Agitation: Restlessness or irritability.
- Delusions or misperceptions: False beliefs not based on evidence.
- Paranoia: Distrust of others.
- Hallucinations: Seeing, hearing, or feeling things that are not there.
Other Symptoms
Other possible symptoms include:
- Problems with blood pressure
- Difficulty regulating body temperature
- Fainting
- Frequent falls
- Constipation
- Urinary incontinence
- Sensitivity to heat and cold
- Sexual dysfunction
- Poor sense of smell
Types of Lewy Body Dementia and Diagnosis
LBD includes two related diagnoses: dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD).
Dementia with Lewy Bodies (DLB)
Individuals with DLB experience a decline in thinking ability, especially in attention, visual perception, and executive function. Over time, they may develop:
- Visual hallucinations early in the course of dementia
- Fluctuations in cognitive ability
- Parkinsonism (slowness of movement, tremor, difficulty walking, or rigidity)
- REM sleep behavior disorder
- More trouble with complex mental activities than with memory
Parkinson’s Disease Dementia (PDD)
PDD occurs when cognitive changes develop more than a year after the onset of motor symptoms associated with Parkinson’s disease.
People with either DLB or PDD eventually develop similar symptoms due to the presence of Lewy bodies in the brain, although DLB symptoms may worsen more quickly than those of PDD.
Benefits of Getting Diagnosed
An early and accurate diagnosis of LBD allows individuals to:
- Receive appropriate medical care and avoid potentially harmful treatments.
- Plan for medical care and arrange legal and financial affairs.
- Build a support team to maximize quality of life.
- Consider enrolling in clinical research.
A diagnosis is also essential for caregivers, helping them understand and prepare for the progression of the disease and plan for their own well-being.
How is Lewy Body Dementia Diagnosed?
Diagnosis involves a combination of physical and neurological examinations, medical history, and various tests, including:
- Medical history and physical examination: Review of symptoms, medications, and past illnesses.
- Medical tests: Blood tests to rule out other conditions. Sleep studies can help diagnose sleep disorders.
- Brain imaging: CT scans, MRIs, and PET scans to detect brain abnormalities and rule out other causes.
- Neuropsychological tests: Assessments of memory and other cognitive functions.
A definitive diagnosis of LBD can only be made through a brain autopsy after death.
Scientists are continuously working to develop better diagnostic tools and treatments for LBD. Research efforts focus on identifying biomarkers and understanding the underlying biology, genetics, and risk factors of the disease.
Seeking Help and Support
If you or a loved one is experiencing symptoms of LBD, it’s essential to consult with a healthcare professional. Several organizations offer resources and support for individuals with LBD and their families:
- NIA Alzheimer’s and related Dementias Education and Referral (ADEAR) Center: Provides information and free publications.
- Alzheimers.gov: Offers information and resources from across the federal government.
- National Institute of Neurological Disorders and Stroke (NINDS): Conducts research and provides information on neurological disorders.
- Lewy Body Dementia Association (LBDA): Offers support, resources, and education.
- Lewy Body Dementia Resource Center: Provides support and resources.
- MedlinePlus: Offers health information from the National Library of Medicine.
- Michael J. Fox Foundation for Parkinson’s Research: Focuses on Parkinson’s research.
- Parkinson’s Foundation: Offers support and resources for individuals with Parkinson’s disease.
