Lewy Body Dementia (LBD)

Lewy body dementia is a neuro-degenerative disease characterized by the presence of Lewy bodies-abnormal proteins-in certain regions of the brain. LBD has no cure.

Lewy body dementia is the second most common type of progressive dementia, after Alzheimer's disease. LBD has certain features in common with other dementia-related diseases such as Alzheimer's and Parkinson's disease.

Other names for Lewy body dementia (LBD) include:

• dementia with Lewy bodies (DLB)
• diffuse Lewy body disease
• cortical Lewy body dementia
• Lewy body variant of Alzheimer's disease.

Lewy Bodies

LBD is caused by the build-up of abnormal proteins in the brain called Lewy bodies. These proteins cause brain cell loss and brain atrophy, resulting in dementia.

Lewy bodies contain the protein alpha-synuclein, which is also associated with Parkinson's disease.

Groundbreaking research is currently exploring the possibility of a common genetic link between Lewy body dementia, Alzheimer's disease and Parkinson's disease.

Regions of the Brain Affected by LBD

With LBD, dementia affects the frontal lobes and the region of the brain that controls speech, thought, expression, reason, organization, planning and calculation, coordination and movement. The frontal lobes are also affected in similar dementia-related diseases, including Alzheimer's disease and vascular dementia.

Symptoms of Lewy Body Dementia

Apart from hallucinations, the symptoms of LBD bear a distinct resemblance to the symptoms of Parkinson's disease (bradykinesia, tremor and rigidity) and Alzheimer's disease (memory loss, confusion, sleep disorders, cognitive impairment and fluctuation).

The four main symptoms of LBD are:

• memory loss: Impaired memory recall patterns are similar to those associated with Alzheimer's disease. Patients have more difficulty remembering current happenings than they do past events. In extreme cases patients are unable to recognize familiar objects or people close to them.
• visual hallucinations: A hallmark and one of the first symptoms of LBD, visual hallucinations tend to be highly graphic and convincing, although generally not alarming, and focused on "silent" humans or animals. Psychiatric disorders and depression are also features of LBD.
• slow movements: Stiffness, rigidity, an expressionless demeanor, tremor and difficulty walking and writing are symptoms similar to those of Parkinson's disease.
• fluctuation: LBD is characterized by a lack of consistency, with symptoms sometimes varying from one extreme to another. For example, slowness and forgetfulness may change suddenly to rapid movements and mental alertness.

High Risks Groups for Lewy Body Dementia

LBD most commonly affects the 65 plus age group, although onset may also occur in young adults. Also, males are at a slightly increased risk compared with females.

Diagnosis of LBD

No single test exists for diagnosing Lewy body dementia. The diagnosis of LBD is largely symptom-based; it also entails a process of elimination to exclude other similar types of dementia.

Medical diagnosis involves examining the patient for the presence of the four main symptoms (memory loss, hallucinations, slowness and fluctuation). The doctor will also take a detailed history. Memory tests, blood tests and an EEG brain scan may also be performed.

Prognosis for Lewy Body Dementia

The prognosis for LBD can be highly variable, but the average life expectancy following diagnosis is currently between five and seven years.

Treatment Options for LBD

As no cure is currently available for the disease, treatments and therapies for Lewy body dementia are entirely targeted at symptom control.

Certain drugs prescribed for Alzheimer's and Parkinson's disease are also used to manage symptoms such as rigidity.

Other palliative drugs for LBD include Aricept® (donepezil HCl), Exelon® (rivastigimine tartrate) and Reminyl® (galantamine HBr). Antidepressants are sometimes prescribed for LBD patients also suffering from depression.

A word of caution...

Drugs for treating rigidity may cause heightened confusion in patients with Lewy body dementia. In addition, neuroleptic drugs used for controlling hallucinations, one of the main symptoms of LBD, can actually exacerbate movement disorders.

Future Research

Lewy body dementia is a continually evolving and exciting area of research, with studies aimed at gaining a better understanding of the structure and formation of Lewy bodies. Findings to date are encouraging, bringing a cure for LBD ever closer.

Resources

Ballard, C.G. (2004). Definition and diagnosis of dementia with Lewy bodies. Dementia and Geriatric Cognitive Disorders, 17 (Suppl. 1), 15-24.

Beers, M.H.