Delirium and dementia with Lewy bodies: distinct diagnoses or part of the same spectrum?

Abstract

Dementia with Lewy bodies (DLB) is recognised as the second most common form of dementia in older people. Delirium is a condition of acute brain dysfunction for which a pre-existing diagnosis of dementia is a risk factor. Conversely delirium is associated with an increased risk of developing dementia. The reasons for this bidirectional relationship are not well understood. Our aim was to review possible similarities in the clinical presentation and pathophysiology between delirium and DLB, and explore possible links between these diagnoses. A systematic search using Medline, Embase and Psychinfo was performed. References were scanned for relevant articles, supplemented by articles identified from reference lists and those known to the authors. 94 articles were selected for inclusion in the review. Delirium and DLB share a number of clinical similarities, including global impairment of cognition, fluctuations in attention and perceptual abnormalities. Delirium is a frequent presenting feature of DLB. In terms of pathophysiological mechanisms, cholinergic dysfunction and genetics may provide a common link. Neuroimaging studies suggest a brain vulnerability in delirium which may also occur in dementia. The basal ganglia, which play a key role in DLB, have also been implicated in delirium. The role of Cerebrospinal fluid (CSF) and serum biomarkers for both diagnoses is an interesting area although some results are conflicting and further work in this area is needed. Delirium and DLB share a number of features and we hypothesise that delirium may, in some cases, represent early or 'prodromal' DLB. Further research is needed to test the novel hypothesis that delirium may be an early marker for future DLB, which would aid early diagnosis of DLB and identify those at high risk.

The Diagnosis of Delirium Superimposed on Dementia: An Emerging Challenge

“…Lewy body disease is the second most common form of dementia in older people with a prevalence of 15%–20% of all dementias at autopsy. 49 The prevalence of older adults with 2 or more DLB symptoms in nursing homes ranges from 16% to 20%. 50 Furthermore, patients with DLB also appear to be more acutely sensitive to minor insults (even subclinical events) and, thus, more delirium “prone.” Consequently, and unsurprisingly, delirium is more commonly diagnosed in DLB than AD 51 with 32% of outpatients with DLB experiencing delirium as opposed to 15% of outpatients with AD.…”

“…49 Currently, when there is a suspicion of DLB, diagnostic biomarkers, such as a DaT SCAN may be helpful, 56 although from a practical point of view, these usually need to be performed after the delirium episode ends. The role of objective biomarkers measurements, such as electroencephalography (EEG) to distinguish delirium and DLB, is appealing, however, EEG patterns in delirium overlap with those seen in DLB, making the differentiation more difficult.…”

Understanding cognition in older patients with cancer

“…Similar to delirium, Lewy Body Dementia is characterized by fluctuating effects on mental functions, particularly in alertness and attention. 61 Sundown syndrome is another distinct clinical entity formally recognized in the DSM-V that can be difficult to distinguish from delirium. It occurs more frequently in the cognitively impaired or institutionalized patient population but is characterized by behavioral disturbances and mood alteration that occurs specifically in the later afternoon or evening.…”

Exosome α-Synuclein Release in Plasma May be Associated With Postoperative Delirium in Hip Fracture Patients

“…α-synuclein (α-syn) is a neuronal protein of 140 residues that localizes predominantly to presynaptic terminals (Burre, 2015). There are several similarities in the core features of POD and α-syn-related cognitive disorders, including Parkinson's disease (PD) dementia and dementia with Lewy bodies; these include fluctuating attention, visual hallucinations, and disorganized thoughts (Sunwoo et al, 2013;Gore et al, 2015;Vardy et al, 2015). A previous clinical study demonstrated that αsyn pathologies in the stomach are associated with POD after gastrectomy (Sunwoo et al, 2013).…”

“…More recently, the same research group reported a significant correlation between POD and PD-related non-motor symptoms (Kim et al, 2018). Given that non-motor symptoms may represent the burden of αsyn deposit, POD is thus hypothesized to be a series of αsyn-related cognitive disorders, and maybe a preclinical stage of α-synucleinopathy (Sunwoo et al, 2013;Gore et al, 2015;Kim et al, 2018).…”