Lewy Body Dementia (LBD)

Lewy Body Dementia (LBD)

Lewy body dementia (LBD) is a type of progressive dementia that leads to a decline in thinking, reasoning, and independent function, caused by abnormal microscopic deposits that damage brain cells over time.

About Lewy Body Dementia

Most experts estimate that Lewy body dementia (LBD) is the third most common cause of dementia, after Alzheimer's disease and vascular dementia, accounting for roughly 10 to 25 percent of all dementia cases.

The specific brain abnormality associated with LBD is named after Frederich H. Lewy, M.D., the neurologist who discovered it while working in Dr. Alois Alzheimer's laboratory in the early 1900s. Alpha-synuclein protein, the main component of Lewy bodies, is found widely throughout the brain, though its normal function is not yet fully understood.

LBD is also found alongside other brain disorders, including Alzheimer's disease and Parkinson's disease. Many people with Parkinson's eventually develop problems with thinking and reasoning, and many people with LBD experience movement symptoms, such as a hunched posture, muscle stiffness, a shuffling walk, and difficulty initiating movement.

These overlapping symptoms and evidence suggest that Lewy body dementia, Parkinson's disease, and Parkinson's disease dementia may share the same underlying abnormality in how the brain processes alpha-synuclein protein. Many people with LBD and Parkinson's disease dementia also experience brain changes specifically associated with Alzheimer's disease.

Symptoms

Symptoms of Lewy body dementia include:

• Changes in thinking and reasoning.
• Confusion and alertness that vary significantly from one time to another, or from one day to the next.
• Parkinson's-like symptoms, such as a hunched posture, balance problems, and muscle stiffness.
• Visual hallucinations.
• Illusions (misperceptions).
• Difficulty interpreting visual information.
• Acting out dreams, sometimes forcefully, a condition known as REM sleep behavior disorder.
• Disruption of the "automatic" (autonomic) nervous system.
• Memory loss that may be significant but tends to be less prominent than in Alzheimer's.

Diagnosis

As with other types of dementia, no single test can conclusively diagnose Lewy body dementia. Currently, LBD is a "clinical" diagnosis, meaning it represents a doctor's best professional judgment regarding the cause of a person's symptoms. The only way to definitively diagnose LBD is through a postmortem autopsy.

Many experts now believe that Lewy body dementia and Parkinson's disease dementia are two different expressions of the same underlying issue with the brain's processing of alpha-synuclein protein. However, most experts still recommend continuing to diagnose LBD and Parkinson's disease dementia as separate disorders.

A diagnosis of Lewy body dementia is given when:

1. Dementia symptoms consistent with LBD develop first.
2. Both dementia symptoms and movement symptoms are present at the time of diagnosis.
3. Dementia symptoms appear within one year of movement symptoms.

A diagnosis of Parkinson's disease dementia is given when a person is first diagnosed with Parkinson's based on movement symptoms, and dementia symptoms do not appear until one year or more afterward.

This type of dementia tends to coexist with brain changes caused by Alzheimer's, which can sometimes make it difficult to distinguish LBD from Alzheimer's disease, especially in the early stages.

Like other types of dementia that damage brain cells, LBD worsens over time and can shorten life expectancy.

Key Differences Between Lewy Body Dementia and Alzheimer's

Source: alz.org

• Memory loss tends to be a more prominent symptom in early-stage Alzheimer's than in early-stage LBD, although advanced LBD can also cause memory problems alongside its more characteristic effects on judgment, planning, and visual perception.
• Movement symptoms are more likely to be a significant cause of disability in early-stage LBD than in Alzheimer's, although Alzheimer's can also cause walking, balance, and navigation problems as it progresses to moderate and severe stages.
• Hallucinations, delusions, and misidentifying familiar people occur significantly more often in early-stage Lewy body dementia than in Alzheimer's.
• REM sleep disturbances are more common in LBD than in Alzheimer's.
• Disruption of the autonomic nervous system — which can cause a drop in blood pressure when standing, dizziness, falls, and urinary incontinence — is far more common in early-stage LBD than in Alzheimer's.

Causes and Risk Factors

Researchers have not yet identified a specific cause of Lewy body dementia. Most people diagnosed with it have no family history of the disorder, and to date no gene has been conclusively linked to the condition.

Treatment and Outlook

There is no treatment that can slow or stop the brain cell damage caused by Lewy body dementia. Current strategies focus on managing symptoms.

If a treatment plan involves medication, it's important to work closely with a doctor to identify the medication best suited to the individual and the most effective dosage. Some medication-related considerations include:

• Cholinesterase inhibitors are currently the mainstay treatment for addressing thinking changes in Alzheimer's, and can also help with certain Lewy body dementia symptoms.
• Antipsychotic medications must be used with great caution in Lewy body dementia. While sometimes prescribed for behavioral symptoms that can also occur in Alzheimer's, these medications can cause serious side effects in as many as 50 percent of people with LBD, including sudden changes in consciousness, swallowing difficulties, acute confusion, episodes of delusion or hallucination, or the emergence or worsening of Parkinson's-like symptoms.
• Antidepressants can be used to treat depression, which is common in Lewy body dementia, Parkinson's disease dementia, and Alzheimer's. The most commonly used class is selective serotonin reuptake inhibitors (SSRIs).
• Clonazepam may be prescribed to treat REM sleep behavior disorder.

Like other types of dementia that damage brain cells, Lewy body dementia worsens over time and can shorten life expectancy.

Source: alz.org