Alzheimer’s and Dementia with Lewy Bodies

Introduction

Alzheimer’s and Dementia with Lewy bodies (DLB) are two separate but similar conditions. Alzheimer's affects the brain's ability to store new information in the form of memories which accounts for the condition's characteristic memory loss. DLB, on the other hand, targets a different set of cognitive functions - specifically problem-solving and reasoning. Although there are tests that can be conducted to more conclusively determine the presence of these conditions, in general, both Alzheimer's and DLB are diagnosed through observation and tracking the progression of an individual’s symptoms.

Dementia with Lewy bodies (DLB)

Dementia with Lewy bodies (DLB) is a progressive type of dementia that leads to a decline in thinking, reasoning and independent function. DLB is characterized by the abnormal build-up of proteins into deposits known as Lewy bodies. This protein is also associated with Parkinson's disease and Parkinson’s dementia disease. People who have Lewy bodies in their brains often have the plaques and tangles associated with Alzheimer's disease. Plaques and tangles are prime suspects in cell death and tissue loss in the Alzheimer's brain. Plaques are abnormal clusters of chemically “sticky” proteins called beta-amyloid that build up between nerve cells.

Symptoms of DLB include:

• Changes in thinking and reasoning
• Confusion and alertness that varies significantly from one time of day to another or from one day to the next
• Parkinson's symptoms, such as a hunched posture, balance problems, and rigid muscles
• Visual hallucinations
• Delusions
• Trouble interpreting visual information
• Acting out dreams, sometimes violently, a problem is known as rapid eye movement (REM) sleep disorder
• Malfunctions of the "automatic" (autonomic) nervous system
• Memory loss that may be significant but less prominent than in Alzheimer's
• Diagnosis

As with other types of dementia, there is no single, conclusive test that can diagnose dementia with Lewy bodies. Currently, DLB is a clinical diagnosis, which means it represents a doctor's best professional judgment about the reason for a person's symptoms. The only way to conclusively diagnose DLB is through a post-mortem autopsy.

It is widely believed by experts that DLB and Parkinson's disease dementia (PDD) are two different expressions of the same underlying problems with brain processing of the protein alpha-synuclein. But most experts recommend continuing to diagnose DLB and Parkinson's dementia as separate disorders.

DLB will be diagnosed when:

• dementia symptoms consistent with DLB develop first
• when both dementia and movement symptoms are present at the time of diagnosis
• when dementia symptoms appear one year after movement symptoms

PDD will be diagnosed when:

• an individual is originally diagnosed with Parkinson's based on movement symptoms, but dementia symptoms don't appear until a year or later.

There have been no specific causes of DLB identified. The majority of people diagnosed with DLB have no family history of the disorder, and no genetic links to DLB have been conclusively identified.

Prognosis: DLB has no cure and there are no existing treatments that can slow down or prevent the brain cell damage caused by DLB; it is a progressive, life-shortening disease. Current strategies focus on utilizing medicines to help alleviate/manage symptoms.

Since Lewy bodies tend to coexist with Alzheimer's brain changes, it may sometimes be hard to distinguish DLB from Alzheimer's disease, especially in the early stages.

Alzheimer’s disease

Alzheimer's disease is the most common cause of dementia. The word dementia describes a set of symptoms that can include memory loss and difficulties with thinking, problem-solving or language. These symptoms occur when the brain is damaged by certain diseases, including Alzheimer's disease. proteins build up in the brain to form structures called 'plaques' and 'tangles'. This leads to the loss of connections between nerve cells, and eventually to the death of nerve cells and loss of brain tissue.

People with Alzheimer's also have a shortage of some important chemicals in their brain. These chemical messengers help to transmit signals around the brain. When there is a shortage of them, the signals are not transmitted as effectively. As discussed below, current treatments for Alzheimer's disease can help boost the levels of chemical messengers in the brain, which can help with some of the symptoms.

Symptoms

1. The symptoms of Alzheimer's disease progress slowly over several years. Sometimes these symptoms are confused with other conditions and may initially be put down to old age.
2. The rate at which the symptoms progress is different for each individual and it's not possible to predict exactly how quickly it will get worse.
3. In some cases, infections, medications, strokes or delirium can be responsible for symptoms getting worse
4. Generally, the symptoms of Alzheimer's disease are divided into three main stages.

Early symptoms

• In the early stages, the main symptom of Alzheimer's disease is memory lapses. For example, someone with early Alzheimer's disease may: forget about recent conversations or events, or misplace items forget the names of places and objects, or have trouble thinking of the right word repeat themselves regularly, such as asking the same question several times show poor judgment or find it harder to make decisions become less flexible and more hesitant to try new things
• There are often signs of mood changes, such as increased anxiety or agitation, or periods of confusion.

Middle-stage symptoms

• As Alzheimer's disease develops, memory problems will get worse. Someone with the condition may find it increasingly difficult to remember the names of people they know and may struggle to recognize their family and friends.
• Other symptoms may also develop, such as: increasing confusion and disorientation – for example, getting lost, or wandering and not knowing what time of day it is obsessive, repetitive or impulsive behavior delusions (believing things that are untrue) or feeling paranoid and suspicious about carers or family members problems with speech or language (aphasia) disturbed sleep changes in mood, such as frequent mood swings, depression and feeling increasingly anxious, frustrated or agitated difficulty performing spatial tasks, such as judging distances hallucinations
• By this stage, someone with Alzheimer's disease usually needs support to help them with their everyday living. For example, they may need help eating, washing, getting dressed and using the toilet.

Later symptoms

• In the later stages of Alzheimer's disease, the symptoms become increasingly severe and distressing for the person with the condition, as well as their carers, friends, and family.
• Hallucinations and delusions may come and go over the course of the illness but can get worse as the condition progresses. Sometimes people with Alzheimer's disease can be violent, demanding and suspicious of those around them.

A number of other symptoms may also develop as Alzheimer's disease progresses, such as:

• difficulty eating and swallowing (dysphagia)
• difficulty changing position or moving around without assistance
• considerable weight loss – although some people eat too much and put on weight
• the unintentional passing of urine (urinary incontinence) or stools (bowel incontinence)
• gradual loss of speech
• significant problems with short- and long-term memory
• In the severe stages of Alzheimer's disease, people may need full-time care and assistance with eating, moving and using the toilet.

Causes

• The exact cause is unknown but we do know that ‘plaques’ and ‘tangles’ form in the brain due to two proteins called amyloid (plaques) and tau (tangles).
• Amyloid is a naturally occurring protein which for a reason that is not yet understood begins to malfunction, creating beta-amyloid which is toxic to the brain cells. Plaques form consisting of dead cells and amyloid protein.
• Tau protein naturally occurs in the brain and helps brain cells communicate with each other but for a reason that is not yet understood, it can become abnormal and “clump together” leading to the death of the brain cells affected.

A number of factors are thought to increase your risk of developing the condition. These include:

• increasing age
• a family history of the condition
• previous severe head injuries
• lifestyle factors and conditions associated with cardiovascular disease

There is no single test for Alzheimer's disease. A GP will first need to rule out conditions that can have similar symptoms, such as infections, vitamin and thyroid deficiencies (from a blood test), depression and side effects of medication.

The doctor will also talk to the person, and where possible someone who knows them well, about their medical history and how their symptoms are affecting their life. The GP or a practice nurse may ask the person to do some tests of mental abilities.

The GP may feel able to make a diagnosis of Alzheimer's at this stage. If not, they will generally refer the person to a specialist. This could be an old-age psychiatrist (who specializes in the mental health of older people) often based in a memory service. Or it might be a geriatrician (who specializes in the physical health of older people), a neurologist (who specializes in conditions of the brain and nervous system) or a general adult psychiatrist (who specializes in mental health in adults) in a hospital.

The specialist will assess the person's symptoms, and how they developed, in more detail. In Alzheimer's disease, there will usually have been a gradual worsening of memory over several months. A family member may be more aware of these changes than the person with suspected Alzheimer's is themselves.

The person's memory, thinking, and other mental abilities will also be assessed further with a pen-and-paper test. When someone with Alzheimer's is tested, they will often forget things quite quickly. They will often not be able to recall them a few minutes later even when prompted.

The person may undergo a brain scan, which can show whether certain changes have taken place in the brain. There are a number of different types of brain scan. The most widely used are CT (computerized tomography) and MRI (magnetic resonance imaging). A brain scan may rule out certain conditions such as stroke, tumor or a build-up of fluid inside the brain. These can have symptoms similar to those of Alzheimer's. It may also clarify the type of dementia. In a person with early Alzheimer's disease, a brain scan may show that the hippocampus and surrounding brain tissue have shrunk.

Prognosis: Currently, there is no cure for Alzheimer's, however, drug and non-drug treatments may help with both cognitive and behavioral symptoms.