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Lewy Body Dementia: Symptoms & Diagnosis

Lewy body dementia (LBD) affects over a million individuals in the United States. Many experts consider it the third most common cause of dementia after Alzheimer’s disease and vascular dementia, consisting of 5-10% of the total cases. Its symptoms typically appear at the age of 50 or above, and it is slightly more prevalent in men than in women.

LBD was first described in 1912 when a German doctor, Dr. Frederich H. Lewy, discovered neuronal inclusions in the brain of people with Parkinson’s disease while working in Dr. Alois Alzheimer’s laboratory. These inclusions or protein clumps, which were then named “Lewy bodies” after him, are a tell-tale sign of Lewy body dementia.

The formation and deposition of Lewy bodies occurs in the neurons of the brain portions responsible for memory, thinking, behavior, and movement. They are chiefly composed of alpha-synuclein proteins that induce chemical changes in the brain, leading to cognitive decline. Although it is abundantly present in the brain, its general function is still unknown.

What causes Lewy body dementia?

It is still unclear what causes Lewy body dementia. Researchers are learning more about its biology and the impact of genetics in order to determine possible causes and risk factors. Studies suggest that the build-up of Lewy bodies results in the loss of neurons responsible for the production of two important neurotransmitters (chemicals that conduct messages between neurons) viz, acetylcholine and dopamine. The former is crucial for memory and learning, while the latter is involved in cognition, movement, behavior, motivation, mood, and sleep.

Researchers have identified various risk factors of Lewy body dementia, among which age is the most prominent factor. Certain health conditions and diseases, particularly Parkinson’s disease and REM sleep behavior disorder, can also increase an individual’s risk of developing LBD.

Family history may also be a risk factor, but LBD is not a genetic disorder. Scientists have reported variants in three genes, APOE, SNCA, and GBA, linked with an increased LBD risk. The cause is, however, not known in most cases.

What are the Signs and Symptoms of Lewy Body Dementia?

Since LBD is a progressive disorder, it slowly develops and worsens with time. A person usually lives up to an average of five to eight years after diagnosis. However, some people may live from two to twenty years.

Similar to Alzheimer’s disease, LBD develops in stages. Symptoms are mild during the early stages, and people usually exhibit relatively normal functioning. However, As the disease progresses, movement and cognition continue to decline. At the late stage, people may become entirely dependent on others for assistance and care.

The development and progression of LBD varies greatly from individual to individual and is contingent on certain factors such as age, health, and severity of symptoms. LBD patients may not experience all the symptoms of the disease. Should a person exhibit a sudden functional or behavioral change, it should be reported to a doctor. The primary symptoms of the disease are changes in cognition, movement, sleep, and behavior.

● Cognitive Symptoms

Lewy body dementia can cause severe cognitive impairment that interferes with daily activities. LBD may seem similar to Alzheimer’s dementia in this regard, but unlike Alzheimer’s, these memory changes may not initially be apparent. Instead, they may arise with it’s progression. The cognitive symptoms include:

  1. Visual hallucinations and sometimes, non-visual (auditory, olfactory, or tactile) hallucinations
  2. Changes in concentration, alertness, and attention that vary throughout the day or from one day to another
  3. Disorganized and unclear ideas
  4. Severe cognitive impairment that often arises with any disease progression
  5. Poor judgment and confusion
  6. Difficulty with language and numbers

● Changes in Movement

Movement problems vary from person to person. Some people may not significantly experience these symptoms for several years, while others may develop them even in the earlier stages of LBD. These symptoms include:

  1. Stiff muscles
  2. Balance problems with frequent falls
  3. Stooped posture
  4. Tremors or shaking, particularly during rest
  5. Slow movement and shuffling walk
  6. Swallowing problems
  7. Loss of coordination

● Changes in Sleep

Although sleep problems are widespread in LBD patients, they are generally undiagnosed. Following are the sleep changes that a person with LBD may experience:

  1. REM sleep behavior disorder (which involves physically acting out dreams while sleeping)
  2. Insomnia
  3. Too much sleep during daytime
  4. Restless leg syndrome (characterized by an overwhelming urge of moving legs when at rest)

● Behavioral Symptoms

People with LBD may experience behavioral and mood changes that may worsen with declining cognitive functioning. The symptoms include:

  1. Depression and anxiety
  2. Apathy and loss of motivation
  3. Agitation and restlessness
  4. Delusions, suspicion, and paranoia

Diagnosis of Lewy Body Dementia

Currently, there is no single test for precisely diagnosing Lewy body dementia. Since its symptoms resemble other types of dementia, such as Alzheimer’s disease and Parkinson’s disease, it becomes difficult to diagnose, particularly in the early stage. The doctors can make the diagnosis with their professional judgment of the symptoms.

Many scientists consider Lewy body dementia and Parkinson’s disease dementia to be two different interpretations of the same fundamental problems arising from the brain’s, processing of the alpha-synuclein protein. However, most experts suggest diagnosing them as distinct disorders.

The diagnosis is LBD when:

  • Dementia symptoms related to LBD develop first.
  • Movement changes and dementia symptoms are diagnosed simultaneously
  • The symptoms of dementia emerge within one year after movement symptoms.

On the other hand, the diagnosis is Parkinson’s disease dementia should an individual, who is already diagnosed with Parkinson’s due to manifestation of movement symptoms, does not exhibit dementia symptoms until after a year or more.

However, due to the co-existence of Lewy bodies with Alzheimer’s brain changes, distinguishing LBD from Alzheimer’s disease may sometimes become challenging, particularly in the early stages.

For diagnosis of LBD, doctors may recommend a few tests such as a neurological and physical examination, blood tests to check hormone levels, assessment of mental abilities, brain scans (an MRI or CT scan), and sleep evaluation.

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