Difference Between Alzheimer's and Lewy Body Dementia

Alzheimer’s disease and Lewy body dementia (LBD) are both types of dementia. They have several similarities, but there are also some clear differences between the two diseases.

Prevalence

LBD: Lewy body dementia is the second most common type of dementia, with an estimated 1.4 million Americans diagnosed.

Alzheimer’s: Alzheimer's disease is the most prevalent type of dementia. As many as 5.8 million Americans are living with Alzheimer’s disease.

Cause

LBD: As the name suggests, Lewy body dementia is believed to be caused by the buildup of Lewy body proteins in the brain. 

Alzheimer's: Alzheimer's is characterized by amyloid plaques and neurofibrillary tangles in the brain.

Researchers are still seeking answers as to what exactly triggers these brain changes in both LBD and Alzheimer's, but they have identified nine specific risk factors that they believe play a role in triggering many cases of dementia.

Cognition

LBD: Symptoms and memory can vary significantly in LBD, such that on one day your grandmother might not recognize you and the next day, she can recall the names of each of her grandchildren.

Alzheimer’s: While cognition can vary somewhat in Alzheimer’s, typically the person’s ability to think and use his memory gradually declines over time. In Alzheimer's symptoms, there is not usually a big variance from one day to the next.

Physical Movement

LBD: Often, one of the early symptoms of LBD is difficulty walking, a decrease in balance and ability to control physical movements. These symptoms are similar to Parkinson’s disease. Frequent falling is also common early in LBD.

Alzheimer’s: Physical deterioration usually does not occur in Alzheimer’s until the disease has significantly progressed, unless the individual has other diseases or illnesses.

Facial Expressions

LBD: Some people who have LBD display a flat affect, where their faces show very little emotion. This is another symptom that may present early in the disease and overlaps with Parkinson’s.

Alzheimer’s: While facial expressions often decrease as the disease progresses, this often doesn’t develop until the middle to later stages of Alzheimer’s.

Visual Hallucinations

LBD: Visual hallucinations, where people see things that aren’t actually there, are quite common in LBD. These hallucinations typically occur earlier in the progression of LBD. 

Alzheimer’s: Hallucinations do occur in Alzheimer’s, but are generally not as prevalent as in LBD. They also tend to occur in the later stages of Alzheimer's disease, as compared to the earlier stages of LBD.

REM Sleep Behavior Disorder

LBD: People with LBD sometimes experience REM sleep behavior disorder, a dysfunction where they physically act out the situations in their dreams. Some research suggests that REM sleep behavior disorder can be one of the earlier predictors of LBD.

Alzheimer’s: REM sleep behavior disorder is not typically present in Alzheimer’s, although other types of sleep disturbances may occur.

Sensitivity to Antipsychotics

LBD: People with LBD have a very high risk of serious side effects if antipsychotic medications are given to them. According to the Lewy Body Dementia Association, 

"It is estimated that a high percentage of [dementia with Lewy bodies] DLB patients exhibit worsening parkinsonism, sedation, immobility, or even neuroleptic malignant syndrome (NMS) after exposure to antipsychotics. NMS is a rare, life-threatening medical emergency characterized by fever, generalized rigidity and breakdown of muscle tissue that can cause renal failure and death. The heightened risk of NMS in DLB mandates that typical or traditional antipsychotics (such as haloperidol, fluphenazine or thioridazine) should be avoided. Atypical antipsychotics have been available for treating mental illness for 25 years and may be safer to use in patients with DLB, but only with extreme caution. Patients with Parkinson's disease dementia (PDD) appear to have a lower risk of an adverse reaction to an antipsychotics, but all patients with LBD should be carefully managed with any antipsychotic drug."

Alzheimer’s: While anyone who takes an antipsychotic medication has a small risk of developing neuroleptic malignant syndrome, individuals with Alzheimer’s are not nearly as prone to developing the extreme sensitivity to antipsychotic medications that people with LBD demonstrate.

Disease Progression

LBD: According to research conducted by James E. Galvin, MD, MPH and other researchers at the Washington University School of Medicine, the median survival time for those in the study with LBD is 78 years old, and survival after onset of Lewy body dementia was 7.3 years.

Alzheimer’s: In the above-referenced study, the median survival time for participants with Alzheimer’s was 84.6 years old, and the survival rate after the beginning of symptoms was 8.4 years. It has been suggested that the difference in the disease progression between LBD and Alzheimer’s can partially be explained by the increase in falls, and therefore injuries and hospitalizations, in those with LBD.

Gender

LBD: Men have a higher chance of developing LBD than women do.

Alzheimer’s: Women have a higher chance of developing Alzheimer’s.

A Word From Verywell

Understanding the differences between Lewy body dementia and Alzheimer's disease can help distinguish between the two conditions and also prepare you for the particular symptoms you or your loved one might experience. Additionally, since some people tend to be more familiar with Alzheimer's disease, it can be helpful to explain how Lewy body dementia is similar to, and different from, Alzheimer's disease.