LBD Cousins and Companions

The last two blogs have been about the Lewy Body family: Parkinson’s disease (PD), Lewy body dementia (DLB and PDD) and REM Sleep Behavior Disorder (RBD or Active Dreams). This one is about some “cousins” and some common companions. These two disorders are cousins--that is, they are related to LBD in some way.

Attention Deficit/Hyperactive Disorder (ADHD) is a mood disorder that attacks young children is a strong predictor of LBD when it perseveres into adulthood. Hyperactivity, poor attention skills and impulsivity are the most common symptoms.  Like LBD, this disorder depletes brain cells of needed chemicals. See our 12/7/12 blog for more about this disorder and its connection to LBD.

Multiple System Atrophy (MSA)  is related to the LB disorders because it is also believed to be caused by damaged alpha-synuclein proteins. It affects men and women equally, primarily in their 50’s. Like Lewy body dementia, MSA attacks movement and the autonomic nervous system. However, it causes neither dementia nor the perceptual symptoms like the delusions and hallucinations that lead to acting-out. LBD and MSA also have other risk factors in common such as Active Dreams. In fact 90% of PwMSA will experience these sleep disturbances.

LBD appears alone only 5% of the time. Autopsies usually show evidence of two or more dementias, even when the symptoms were specific to only one. The most common dementias are:

Alzheimer’s Disease (AD). You can’t talk about LBD without mentioning Alzheimer’s. DLB, the type of Lewy body dementia that starts before motor dysfunctions do, is often diagnosed first as AD. In fact, until recently, it almost always was. Even PDD was diagnosed as Parkinson’s with Alzheimer’s until the late 1990’s. With AD, damaged tau and beta-amyloid proteins kill off neurons generally (rather than selectively as Lewy bodies do) and therefore, the damage is more complete—no fluctuations. Also, AD’s damaged proteins tend to stay in the cerebral cortex—they don’t migrate to other areas of the brain as Lewy bodies do. Thus you will often see impaired cognitive abilities, especially memory, with a fairly healthy body until late in the progress of the disorder, when so many brain cells are dead that anything may be impaired.

Frontotemporal Dementia (FTD).  Although this disorder is often misdiagnosed as LBD, it is caused by an abnormal tau protein, and thus is therefore more closely related to AD. It is the most common dementia for people under 60 years of age—even more common than Alzheimer’s. This disorder affects one’s ability to empathize, making a PwFTD appear unfeeling and selfish. As with LBD, thinking errors and delusions are common. However, there are fewer physical or memory problems. This, along with its early onset, makes it difficult to identify and it is often not diagnosed as anything but a personality defect that the person is unwilling to change. Like LBD, it is most common in men. However,FTD is not likely to accompany Lewy body dementia.

Vascular Dementia (VaD) or Multi-Infarct Dementia (MID). When a series of small strokes (infarcts) deprive the brain of vital oxygen, VaD symptoms appear. Disorientation in familiar locations, walking with rapid, shuffling steps, incontinence, laughing or crying inappropriately, difficulty following instructions, and problems handling money may appear suddenly and worsen with additional strokes. High blood pressure, cigarette smoking, and high cholesterol are some of the risk factors for stroke that may be controlled to prevent vascular dementia.  It often appears as a third dementia in autopsies but may not be recognized in life because the symptoms are so similar to other dementias. Even the strokes that cause it may go unnoticed because they will appear as simply a few “bad” days, a fluctuation that is common to LBD.

Mixed Dementias. Alzheimer’s is the most common dementia to accompany DLB. It may also accompany PDD, but much less often. Frontotemporal dementia and VaD are also common with both types. Therefore, when you see symptoms more common to Alzheimer’s, such as wandering, it is probably because AD is actually present. A sudden drop in functioning may herald the presence of VaD, especially if the functioning does not return to previous levels.

A Lewy Body Family History

It all started back in 1817 when Dr. Parkinson described “shaking palsy.” Eventually, the disease was named after him. Fast forward almost a hundred years: In 1912, Dr. Lewy was searching for the cause of PD in the autopsied brains of Parkinson’s patients. He found that the microscopic round bodies of protein that were eventually named for him were always present in the area of the brain where movement is controlled. Thus, since 1912, it has been known that Lewy bodies and Parkinson’s occur together, although, until the last decade, they weren’t sure which caused which.

Fast forward again, to the 1980’s. Dr. Kosaka found these same Lewy bodies in the cerebral cortex, or the thinking center, of the brains of people who had displayed the symptoms we now relate with Lewy body dementia.

However, even though researchers knew the same “Lewy bodies” were present in both Parkinson’s and in that dementia Dr. Kosaka had found, dementia was not considered a symptom of PD until the early 1990’s. They were thought to be two separate diseases that often occurred together: PD and ‘dementia,’ usually Alzheimer’s. Then, in 1994, Parkinson’s disease with dementia (PDD) was recognized as part of the Parkinson’s picture and given its own insurance code.

Two years later, in 1996, a world-wide group of dementia specialists convened and developed clinical criteria for Dementia with Lewy Bodies (DLB).  At that time, the terms ‘dementia with Lewy bodies’ and ‘Lewy body dementia’ were used synonymously. However, it was not yet associated, at least formally, with PD. Dementia specialists treated LBD and movement specialists treated PDD, as a symptom which could occasionally show up in late stage PD.

By the early 2000’s specialists were beginning to recognize the similarities between PDD and LBD/DLB.  Finally, in 2005, a group of movement and dementia specialists met together and agreed that Lewy bodies caused both types of dementia and that their cognitive symptoms were similar. At that time, they determined that ‘DLB’ described the type of dementia that started prior to any motor symptoms and that ‘LBD’ was an umbrella term for both ‘DLB’ and ‘PDD’.

Notice that the experts were now saying that Lewy bodies caused these disorders (and PD as well)--not the other way around. And that’s why we now say that the Lewy body family has at least three members: PD, DLB and PDD. They are all related. PD occurs when the Lewy bodies reside in the midbrain where motor functions are controlled. DLB occurs when Lewy bodies reside in the cerebral cortex where cognitive abilities are controlled. And PDD occurs when the Lewy Bodies migrate from the midbrain to the cortex and both motor and cognitive functions are compromised.

As to what causes the damage that results in Lewy bodies, that’s still up for grabs. However, the evidence is becoming stronger and stronger that it is a combination of genetics and toxins.

Next week’s blog presents a more scientific vies of the Lewy body family.

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