Dementia With Lewy Bodies: Symptoms, Causes And Relationship With Alzheimer’s
The term “dementia” refers to a group of diseases that cause a progressive deterioration in functioning as a result of brain degeneration. Although it is not as well known as dementia due to Alzheimer’s disease, the one that occurs as a result of the accumulation of Lewy bodies is also very prevalent.
In this article we will describe What is dementia with Lewy bodies and what are its symptoms and causes? main. We will also analyze the pathophysiological characteristics of this disease in comparison with those of Alzheimer’s and Parkinson’s, which share notable characteristics, and we will briefly review its history.
Dementia with Lewy bodies is a neurodegenerative disease that falls within the group of cortical dementias, such as Alzheimer’s disease and Pick’s disease. In this group of disorders, the brain deterioration typical of dementia mainly affects the cortex, which causes a very significant alteration in higher cognitive functions.
Consequently, people with some type of cortical dementia usually present symptoms such as memory problems, disorientation, emotional instability, impulsivity and impairment of complex cognitive processes such as abstraction and social judgment. These functions depend primarily on the activity of the frontal lobes of the brain.
Dementia with Lewy bodies is associated with presence of abnormal cellular structures in the brain relatively specific to this disease, and which give it its name. Degeneration of the cerebral cortex causes multiple symptoms and signs, the most characteristic being parkinsonism, visual hallucinations and fluctuations in attention.
This disease was first described by Kenji Kosaka in 1976; However, the deposits known as Lewy bodies had been discovered by Frederic Lewy in the early years of the 20th century. In the 1990s, advances in diagnostic techniques made it possible to detect the disease by observing the brain after death.
It is currently known that this is the third most common type of dementia, surpassed only by that due to Alzheimer’s disease and by mixed dementia, in which the anterior and vascular dementias are combined. Epidemiology research indicates that between 10 and 15% of dementias are due to Lewy bodies
This dementia occurs more frequently in men than in women, although the differences in prevalence are not very large. It is more common in people who are over 60 years old, but it tends to appear later: the average age of onset of symptoms is around 75 years.
Main symptoms and signs
Dementia with Lewy bodies is a progressive disease; As such, the deficits and alterations it causes increase as the disease progresses and spreads throughout the brain. Despite being a cortical dementia, memory problems are not very evident during the first phases of the disease, although they become so later on.
The cardinal symptoms and signs of dementia with Lewy bodies There are three: fluctuations in attention and alertness, which cause episodes of confusion; parkinsonian-type manifestations such as rest tremors, rigidity and slowness of movement; and recurrent visual hallucinations, which can be very vivid.
Throughout the course of the disease, other dysfunctions also appear in executive processes, such as those that affect visuospatial cognition and temporal and spatial orientation, as well as delusions, difficulties walking, frequent falls, symptoms typical of depression and alterations. REM or REM (“rapid eye movement”) sleep.
Although the exact cause of dementia with Lewy bodies is not known, it is known that it is associated with the PARK11 gene and that It also shares a genetic basis with Alzheimer’s disease related to failures in the synthesis of apolipoprotein E. However, most cases of this disease are not due to hereditary factors.
At a pathophysiological level, the most characteristic feature of this dementia is the presence of Lewy bodies, accumulations of the protein alpha-synuclein in the cytoplasm of neurons. This alteration is due to errors in phosphorylation, a process related to protein activity and metabolism.
Relationship with Alzheimer’s and Parkinson’s dementias
Lewy bodies not only appear in the dementia at hand, but are also present in Parkinson’s disease, multiple systemic atrophy and Alzheimer’s disease; In the latter case, they are found specifically in the CA2-3 region of the hippocampus, a fundamental structure in memory consolidation.
In addition to Lewy bodies we can find amyloid plaques, one of the typical signs of Alzheimer’s dementia, and deficits in the neurotransmitters dopamine and acetylcholine, as occurs in Parkinson’s disease. This is why Lewy disease is often spoken of as a midpoint between the other two, etiologically and symptomatically.
Unlike what happens in Alzheimer’s disease, in dementia with Lewy bodies, atrophy in the cortex of the middle part of the temporal lobes is not observed during the early stages of the disease. This fact explains part of the symptomatic differences between both dementias, particularly the course of memory problems.
