Psychiatric Symptoms as Indicators of Neurodegenerative Processes: Lewy Body Disease as an Example of the Essential Collaboration Between Neurology and Psychiatry

Mansouri, Wafaa and Salim, Jalal and Abbou, Abdelilah Nait and Amara, Yahya and Mouhadi, Khalid and Khalid, Mohamed (2025) Psychiatric Symptoms as Indicators of Neurodegenerative Processes: Lewy Body Disease as an Example of the Essential Collaboration Between Neurology and Psychiatry. International Journal of Science and Research Archive, 15 (3). pp. 1766-1770. ISSN 2582-8185

Introduction: Psychosis encompasses a group of psychiatric disorders within the spectrum of psychotic disorders, primarily characterized by a significant disruption in contact with reality. The typical age of onset for psychotic disorders ranges from late adolescence to early adulthood, approximately between 15 and 35 years. However, in some cases, psychotic symptoms may emerge after the age of 40, at which point the condition is termed late-onset psychosis. This unusual clinical presentation should prompt, as a first-line consideration, a search for an underlying organic etiology, most notably a neurodegenerative disorder. Among these, Lewy body disease (LBD) serves as a significant differential diagnosis due to its frequent association with early visual hallucinations, pronounced cognitive fluctuations, and extrapyramidal signs.

Case Description: The patient is a 58-year-old man presenting to psychiatric services for the first time with symptoms of anxiety and depression, reportedly beginning during the COVID-19 pandemic. He complained of unfounded fears, social withdrawal, low mood, and sleep disturbances. He was prescribed antidepressants and anxiolytics and referred for a neurological consultation.

The neurological examination, cranial CT scan, and standard blood tests were unremarkable. The clinical course remained stable until, four years later, the patient suddenly exhibited childlike and disinhibited behavior, developed psychomotor instability, and experienced worsening sleep disturbances. A therapeutic shift to antipsychotic medication was implemented. The psychiatric picture then evolved to include visual and auditory hallucinations, as well as delusions of persecution and abandonment. A new neurological assessment was requested.

The neurological examination at that time revealed a Parkinsonian syndrome characterized by tremor and akinetic-rigid features (pre-existing but exacerbated by neuroleptic treatment), along with deficits in working memory and fluctuating attention and alertness. A comprehensive metabolic and infectious workup for dementia yielded negative results. A brain MRI showed grade 1 vascular leukoencephalopathy according to the Fazekas scale. A diagnosis of Lewy body disease (LBD) was subsequently established.

The patient was started on 600 mg of quetiapine per day and 50 mg/day of piribedil (a dopamine agonist), resulting in an almost complete resolution of symptoms.

Discussion: Late-onset psychosis affects individuals older than 40 and is secondary in approximately 60% of cases, often due to neurodegenerative disorders, medications, or toxic exposures. Lewy body disease (LBD) is a neurodegenerative condition characterized by a classic triad of symptoms: fluctuating cognitive impairment, early visual hallucinations, and Parkinsonian syndrome. A diagnosis of probable LBD is established when the triad of dementia, parkinsonism, and psychiatric symptoms is present. Distinguishing between these clinical entities relies on a careful analysis of the nature and characteristics of hallucinations and delusions, the progression of symptoms over time, and their association with neurological signs. In our case, psychiatric symptoms were the predominant clinical feature for several years, during which neurological examinations showed no significant findings. Parkinsonian signs and cognitive decline developed gradually over time. Ultimately, the sudden worsening and complexity of the psychiatric presentation led us to reconsider the initial diagnosis in close collaboration with our neurology colleagues.

Conclusion: Late-onset psychosis requires particular attention due to the possibility of an underlying secondary cause, its higher morbidity and mortality compared to primary psychotic disorders, and the need for tailored therapeutic strategies based on the etiology. Our case—Lewy body disease (LBD) with psychiatric onset—illustrates a clinical situation that necessitates close collaboration between neurologists and psychiatrists.