Irma Otero Vázquez, a healthcare psychologist and therapist, delves into Lewy body disease, assigning great importance to its symptomatology and differences compared to Parkinson’s and Alzheimer’s associated dementia.

The increase in population life expectancy has led to a rise in the incidence and prevalence of neurodegenerative diseases. Lewy body dementia is a significant factor behind much of this issue, making it essential to understand and treat it to reduce the socioeconomic and personal costs associated with it.

What are Lewy bodies?

Lewy bodies are abnormal accumulations of the alpha-synuclein protein generated in the nervous system at cortical and subcortical levels. It has been demonstrated that abnormalities in this protein lead to neuronal dysfunction or, in some cases, neuronal death. This results in a significant reduction of dopamine, cholinergic pathology, and dysfunctions in other neurotransmitters, giving rise to specific symptomatology. Therefore, disorders with this etiology are termed alpha-synucleinopathies (Prasad et al., 2023).

Neurodegenerative/dementia diseases can be classified based on various criteria, one of which is molecular pathology (Kovacs, 2017), encompassing alpha-synucleinopathies and consequently Lewy bodies.

Lewy body disease

The concept of Lewy body disease has recently been proposed to encompass a group of alpha-synucleinopathies that present these formations due to clinical and pathological overlap among disorders (Menšíková et al., 2022). Thus, the following clinical-pathological entities are identified:

• Parkinson’s disease.

• Lewy body dementia.

• Multiple system atrophy.

Additionally, under the label of Lewy body disease, Parkinson’s disease dementia and Lewy body dementia can be included (Walker et al., 2015). Therefore, precise terminology will be crucial when referring to one pathology or another.

It is worth noting that motor, cognitive, behavioral, and psychological presentations differ among these entities, so this heterogeneity in symptomatology and course must be carefully considered. The underlying basis for this is still limited, but certain studies suggest that the concomitant presence of beta-amyloid and tau pathologies, characteristic of Alzheimer’s Disease, could influence these differences (Coughlin et al., 2020).

Lewy body dementia

Lewy body dementia is the second most common cause of neurodegenerative disorder, after Alzheimer’s disease, in individuals over 75 years old. However, the prevalence reported in various studies varies. This variability may indicate underdiagnosis, as it is sometimes misclassified as Alzheimer’s type dementia or Parkinson’s disease with mild cognitive impairment due to similarities in symptomatology (Milán-Tomás, Fernández-Matarrubia, y Rodríguez-Oroz, 2021).

Its etiology is unknown, but there is a suggested interaction between genetic and environmental factors (Bellas-Lamas, 2012). Most cases of Lewy body dementia are typically sporadic. However, some cases have been reported with autosomal dominant inheritance involving mutations in specific genes (Walker et al., 2015).

This disorder usually begins between the ages of 70 and 80, with an insidious onset and is associated with a faster functional decline compared to Alzheimer’s disease, featuring a fluctuating and progressive course (Bellas-Lamas et al., 2012).

Symptomatology

There are several core features in the presentation of Lewy body dementia that encompass both Parkinson’s disease dementia and Lewy body dementia.

Parkinsonism

This symptom results from the loss of dopaminergic neurons in the nigrostriatal pathways and the presence of Lewy bodies. Bradykinesia and rigidity are the most common signs (>85%). Typically, parkinsonism is symmetric, and signs of extrapyramidal dysfunction are observed along with myoclonus. All of these increase the risk of swallowing problems or falls, as well as a poor response to levodopa/carbidopa medication unlike in Parkinson’s disease (Prasad et al., 2023).

REM sleep disorder

This is a parasomnia where the typical muscle atony of REM sleep is deficient. It is present in 76% of patients and is characterized by actions, vocalizations, and movements reflecting their dreams. It often appears years before other symptoms and may be accompanied by confusing awakenings, daytime sleepiness, insomnia… (Prasad et al., 2023).

Cognitive fluctuations

These fluctuations are similar to what occurs during a delirium episode and refer to clear differences in cognition, attention, and arousal levels, occasionally causing daytime drowsiness or alterations in thought processes. Changes in behavior, incomprehensible speech, altered consciousness, or a decline in visuospatial skills can also be present (Gomperts, 2016 and Milán-Tomás et al., 2021).

Hallucinations

The most common are visual hallucinations, occurring in 80% of patients. These are often highly complex and emotionally neutral, often taking the form of detailed animals or people. Individuals are usually aware of these and communicate them to family members. Sometimes, they may describe the feeling of a presence or someone walking nearby. Auditory hallucinations are less common and typically verbal (Prasad et al., 2023).

Impaired autonomic nervous system regulation

The prevalence of this symptom class is 90%, with the most common being: orthostatic hypotension, urinary incontinence, hyposmia, constipation, erectile dysfunction, gastroparesis, or seborrhea (Prasad et al., 2023; Bellas-Lamas et al., 2012).

Neuroleptic sensitivity

The loss of dopaminergic neurons in such patients is partially responsible for their hypersensitivity to antipsychotics. As a consequence of their use, parkinsonism tends to worsen, increasing the risk of mortality due to neuroleptic malignant syndrome. Certain manifestations in these individuals may be evaluated in emergency settings as psychotic symptoms, with administering these drugs having significant consequences for their health (Gomperts, 2016).

Neuropsychological profile of Lewy body dementia

Having discussed the core characteristics of Lewy body dementia, we will now focus particularly on the neuropsychological profile of Lewy body dementia as it differs to some extent from that associated with Parkinson’s.

Patients with this pathology exhibit cortical and subcortical alterations (Yubero et al., 2011), particularly affecting cognitive functions as outlined below.

On one hand, visuoconstructional deficits are observed even in prodromal stages of the disease, where errors in reproducing complex figures like the Rey figure are identified. Some authors suggest that these alterations may be due more to visual-perceptual and praxic problems, requiring detailed exploration in this regard (Kempt et al., 2017). Additionally, deficits can be seen in visuospatial tasks such as discriminating shapes and sizes, and in visually organizing objects (Yubero, 211). Attention and executive function failures are apparent, especially in terms of distractibility, inhibition, task initiation, attentional shifting, and working memory. Regarding memory function, deficits are mild and relatively stable initially (Subirana et al., 2011), with notable errors in visual recognition, while verbal memory seems more preserved. However, these difficulties may arise from visual or attentional impairments. In this domain, failures in information retrieval were also observed (Kempt et al., 2017). Lastly, in the language domain, the most significant alterations were found in verbal fluency (Yubero et al., 2011).

As for neuropsychiatric manifestations, symptoms of anxiety, depression, and apathy are the most common and tend to appear early on and persist throughout the disease’s progression (Donaghy et al., 2018 and Prasad et al., 2023).

Differences between Lewy body dementia and Parkinson’s associated dementia

Lewy Body Dementia and Parkinson’s associated dementia share around 85% of symptomatology, making them challenging to differentiate. The key criterion to distinguish between the two disorders lies in timing (Martini, 2020), as established by McKeith et al. in 2017, indicating that if cognitive symptoms debut before or within a year of the onset of parkinsonism, the diagnosis of Lewy body dementia is made (Armstrong, 2021). Also, extrapyramidal symptoms tend to be more evident in Parkinson’s associated dementia.

On a cognitive level, there are differentiating symptoms such as visuospatial and visuoconstructive functions, visual and verbal memory, which are typically more impaired in Lewy Body Dementia, along with visual hallucinations and delusions being more common in Lewy Body Dementia (Milán-Tomás et al., 2021). Another differentiating factor is the accumulation levels of amyloid in the brain parenchyma, more frequent in LBD (Prasad et al., 2023).

Differences between Lewy body dementia and Alzheimer’s disease (AD)

Lewy Body Dementia and Alzheimer’s Disease in their early stages share certain similarities that complicate their accurate diagnosis, such as episodic memory failures present in both pathologies (Yubero, 2011). However, this is not entirely accurate as errors exhibited in Alzheimer’s Disease are related to storage and encoding processes, unlike those in Lewy Body Dementia, where the issue lies in retrieval processes (Ciofane et al., 2019). Furthermore, in the visuospatial domain, deterioration is more acute and rapid in Lewy Body Dementia (Milán-Tomás et al., 2021), as well as in attentional deficits with non-existent fluctuations in Alzheimer’s Disease, and in executive and visuoconstructive function. The latter is significantly affected compared to other impairments in Lewy Body Dementia (Yubero, 2011).

Treatment of Lewy body dementia

Currently, there are no effective therapies that can alter the course of Lewy body dementias. Therefore, interventions focus on treating the most prominent symptoms with the aim of alleviating their impact on both the individual and their environment’s quality of life (Milán-Tomás et al., 2021).

Starting with pharmacological treatments, attention is given to those that worsen the individual’s clinical condition, such as benzodiazepines and opioids, among others. Additionally, there are various pharmacological options for each symptom: for cognitive symptoms, cholinesterase inhibitors, donepezil, and rivastigmine are recommended, while for sleep disorders, melatonin is commonly used (Armstrong, 2021).

Regarding non-pharmacological treatments, which have emerged as a suitable therapeutic option for such pathologies, physical therapy (which could be beneficial in managing extrapyramidal signs), occupational therapy, speech therapy, and swallow evaluations (recommended for improving dysphagia, fall prevention, and enhancing functionality), cognitive rehabilitation (for its impact on quality of life, satisfaction, and mood), and environmental modifications or music therapy (for addressing behavioral symptoms) can be mentioned (Guidi et al., 2023 and Armstrong, 2023).

In conclusion, the therapeutic approach to these pathologies must be taken from a multidisciplinary perspective to address the comprehensive symptom complex effectively.

Conclusions

Lewy body dementia is a far broader construct than previously thought, and the subtle distinctions between one pathology and another can be challenging to discern. Therefore, as professionals, we must exercise extreme care in our evaluations to identify key signs and symptoms that will lead us towards a more accurate diagnosis. The importance of this lies not only in achieving an accurate pathological classification but also in how crucial it is in proposing an appropriate treatment that genuinely improves the quality of life and functionality of both users and caregivers.

References

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