Overview

Dementia with Lewy bodies (DLB) is a neurodegenerative disorder (or dementia) characterized by physical (resemble Parkinson’s disease), psychiatric (visual hallucinations), and cognitive (fluctuating cognition) symptoms. It is the second most common type of age-related dementia, preceded by Alzheimer’s disease. Initially, an individual may be diagnosed with mild cognitive impairment when deficits have not significantly disrupted daily life. As the disease progresses, an individual with dementia with Lewy bodies may increasingly require assistance with activities of daily living. There is currently no cure for dementia with Lewy bodies. However, there are a number of pharmacological and non-pharmacological treatments to help slow down the progression of the disease and improve quality of life.

Symptoms

Core symptoms encompass several domains, including physical, psychiatric, and cognitive. Physically, individuals with dementia with Lewy bodies develop parkinsonism, such as slowness, rigidity, and lack of balance. Psychiatrically, they may have visual hallucinations, which are typically well-formed, detailed, and animate figures. Regarding cognition, they can have fluctuating mental status between periods of lucidity and confusion over the course of minutes, hours, or days. Additionally, they may exhibit difficulties with attention, visuospatial abilities, and executive functions (high-order cognitive abilities such as planning, organizing, and problem-solving). Unlike with Alzheimer's disease, individuals with dementia with Lewy bodies have relatively preserved memory function. Other features of the disease include repeated falls, sensitivity to typical antipsychotic medications, sleep disorders (e.g., acting out dreams, excessive daytime sleepiness), delusions, hallucinations of other sensory modalities (auditory, olfactory, and tactile), depression, anxiety, and apathy. In most cases, not all of these symptoms will be present, especially in the early stages of the disease. Some of these symptoms overlap with Parkinson’s disease dementia (PDD), which is when people with Parkinson’s disease starts to develop significant cognitive decline. To distinguish between them, cognitive symptoms precede motor signs in dementia with Lewy bodies, while motor symptoms precede cognitive disturbance in PDD (1).

Neuropathology

Dementia with Lewy bodies pathology is characterized by the accumulation of Lewy bodies, which are abnormally formed protein alpha-synuclein, in the cortical, subcortical, and brainstem regions of the brain. Mixed pathologies of Lewy bodies and plaques and tangles that are characteristic of Alzheimer's disease are found in a large number of autopsy cases (1). Neuroimaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) can reveal the loss of dopamine transporter proteins in the basal ganglia, which is currently the gold standard for dementia with Lewy bodies diagnostic imaging. PET and SPECT scan can also identify hypometabolism in the occipital region of the brain with relative sparing of the medial temporal lobes (the region affected in Alzheimer's disease) (2).

Prevalence

Dementia with Lewy bodies is the second most common form of dementia in older adults, accounting for 20% of dementia cases at autopsy. The prevalence of dementia with Lewy bodies is between 0% and 5% of the general population and 0% and 31% of dementia cases (3).

Course

An individual may be diagnosed with mild cognitive impairment (MCI) in the beginning stages of the illness when the deficits do not substantially interfere with daily life. MCI is a dynamic, transitional stage between normal cognitive status (compared to others of similar age and educational background) and dementia. People with MCI can either revert back to normal cognition (especially if the cause of the cognitive dysfunction is modifiable, such as mood disorders) or progress to dementia. The average disease duration for dementia with Lewy bodies is 5 to 7 years (4).

Treatments

There is currently no cure for dementia with Lewy bodies. Pharmacological treatments are used to target specific symptoms. Levodopa may be utilized to treat motor symptoms, although they are not as effective in treating dementia with Lewy bodies as Parkinson’s disease. Cholinesterase inhibitors may be used for cognitive and psychiatric disturbances, which may be more beneficial for dementia with Lewy bodies than Alzheimer's disease based on preliminary research. Typical antipsychotic medications should be avoided due to the increased sentivity of these medications in individuals with dementia with Lewy bodies. Non-pharmacological treatments are also utilized to improve quality of life. Cognitive and behavioral training and stimulation can improve cognition, behavior, and mood. A multisystem approach that involves cognitive and behavioral intervention as well as physical exercise and social stimulation yield the best results (5).

By Michelle Chen

References

  1. McKeith, I, Mintzer, J, Aarsland, D, Burn, D, Chiu, H, Cohen-Mansfield, J & Gauthier, S (2004). Dementia with Lewy bodies. The Lancet Neurology3(1), 19-28.
  2. Mak, E, Su, L, Williams, G, & O’Brien, J (2014). Neuroimaging characteristics of dementia with Lewy bodies. Alzheimer's research & therapy6(2), 18.
  3. Troster, A & Browner, N (2013). Movement Disorders with Dementia in Older Adults. In L. D. Ravdin & H. L. Katzen (Eds.), Handbook on the Neuropsychology of Aging and Dementia (pp. 333-362). New York, NY, USA: Springer.
  4. Lewy Body Dementia Association. The role of palliative and hospice care in Lewy Body Dementia. Retrieved from: https://www.lbda.org/go/role-palliative-and-hospice-care-lewy-body-dementia
  5. McKeith, I, Dickson, D, Lowe, J, Emre, M, O'brien, J, Feldman, H, & Aarsland, D (2005). Diagnosis and management of dementia with Lewy bodies third report of the dementia with Lewy bodies consortium. Neurology65(12), 1863-1872.