Dementia with Lewy bodies: symptoms, causes and relation to Alzheimer’s disease

This brain disease causes memory problems, disorientation and other complications.

The term "dementia" refers to a group of diseases that cause progressive deterioration of functioning as a result of degeneration of the brain. Although not as well known as dementia due to Alzheimer's disease, dementia resulting from the accumulation of Lewy bodies is also very prevalent.

In this article we will describe what dementia with Lewy bodies is and what its main symptoms and causes are. causes. We will also analyze the pathophysiological characteristics of this disease in comparison with Alzheimer's and Parkinson's, which share notable features, and we will briefly review its history.

What is dementia with Lewy bodies?

Dementia with Lewy bodies is a neurodegenerative disease that belongs to the group of cortical dementias, such as Alzheimer's disease and Pick's disease. In this group of disorders, the brain deterioration typical of dementias affects mainly 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 impaired 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 the presence in the brain of cellular presence of abnormal cellular structures in the brain that are relatively specific to this disease, and which give it its name. The degeneration of the cerebral cortex causes multiple symptoms and signs, the most characteristic being parkinsonism, visual hallucinations and fluctuations in attention.

History, diagnosis and prevalence

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 now known to be the third most common type of dementia, surpassed only by dementia due to Alzheimer's disease and mixed dementia, in which dementia and vascular dementia are combined. Epidemiological research indicates that 10-15% 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 over 60 years of age, but 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 impairments it causes increase as the disease progresses and spreads throughout the brain. Despite being a cortical dementia, memory problems are not very evident, memory problems are not very evident during the early stages of the disease, although they become of the disease, but become so later on.

The cardinal signs and symptoms of dementia with Lewy bodies are as follows are three: fluctuations in attention and alertness, leading to episodes of confusion; parkinsonian-like manifestations such as resting tremors, rigidity and slowness of movement; and recurrent visual hallucinations, which can be very vivid.

Other dysfunctions in executive processes, such as those affecting visuospatial cognition and temporal and spatial orientation, as well as delusions, walking difficulties, frequent falls, depressive symptoms and REM or REM ("rapid eye movement") sleep disturbances, also appear during the course of the disease.

Causes and pathophysiology

Although the exact cause of dementia with Lewy bodies is not known, it is known to be associated with the PARK11 gene and also shares a genetic basis with Lewy body disease. also shares a genetic basis with Alzheimer's disease, related to failures in the synthesis of Lewy body synthesis.related to failures in apolipoprotein E synthesis. However, most cases of this disease are not due to hereditary factors.

At the pathophysiological level, the most characteristic feature of this dementia is the presence of Lewy bodies, accumulations of the alpha-synuclein protein alpha-synuclein. Lewy bodies, accumulations of the protein alpha-synuclein in the cytoplasm of neurons. 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 in question, 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 the consolidation of memory.

In addition to Lewy bodies we can find amyloid plaques, one of the typical signs of Alzheimer's dementia, and deficits in the neurotransmittersone of the typical signs of Alzheimer's dementia, and deficits in the neurotransmitters dopamine and acetylcholine, as in Parkinson's disease. This is why Lewy's disease is often referred to as a midpoint between the other two, etiologically and symptomatically.

Unlike what happens in Alzheimer's disease, in dementia with Lewy bodies atrophy is not observed in the cortex of the medial part of the temporal lobes during the early stages of the disease. This fact explains part of the symptomatic differences between the two dementias, particularly the course of memory problems.