Neural Network Impairment

IN THIS ISSUE: CLP 2021 | Best Practice | COVID-19 Task Force | Proactive C-L Psychiatry | Diversity | Neural Impairment

Warning Signs for Cerebral Cortical Neural Network Impairment in Delirium

Bedside analysis recommended for all older patients who are medically ill or presenting for surgery

The prevalence of abnormal executive function (EF) and primitive reflexes (PR) among older hospitalized patients with delirium, with or without comorbid dementia, is an under-reported indicator of cerebral cortical neural network impairment, say researchers.

PR and EF deficit signs are consistent with reduced neural network integration during delirium—even worse in those with dementia whose baseline structural injury impairs network connectivity with frontal regions.

Researchers from the Universidad Pontificia Bolivariana, Colombia, and the Department of Psychiatry, Indiana University School of Medicine, Indianapolis—who report their findings in the January/February edition of the Journal of the Academy of Consultation-Liaison Psychiatry (JACLP)—recommend a simple bedside assessment of PR and EF signs to help assess for delirium as an indicator of cortical network impairment, even in patients with dementia.

José Franco, MS, MD
José Franco, MS, MD

Besides advanced age, the main predisposing factor for delirium among older people is preexisting cognitive impairment, including dementia. Symptoms overlap with deficits in language and higher-order cognitive functions depending on the type of dementia. When comorbid, delirium symptoms overshadow those of the underlying dementia, and delirium should be diagnosed and managed as an urgent clinical priority, say the researchers.

EF is a broad set of cognitive skills responsible for planning, initiation, sequencing, switching mental sets, and monitoring complex goal-directed behavior, subserved by the prefrontal cortex. These are necessary for independent human interaction and include abstraction, conceptualization, self-organization, self-regulation, working memory, judgment, insight, initiation, and perseveration, which are largely developed by adolescence. EF provides oversight to other cognitive behavioral functions of the brain and are assessed by cognitive tests and physical examination.

PR are adaptative and reflexive motor reactions to stimuli present in neonates and infants during early brain maturation associated with feeding and attachment but disappear with frontal lobe maturation in early childhood.

The appearance of EF deficits or the reappearance of PR (also called frontal release signs) can occur with older people with a cognitive disorder such as dementia.

Sparse earlier research on EF and PR is described in the paper. The researchers’ study at Clínica Universitaria Bolivariana during a six-month period was with 233 patients aged 60+ who were assessed over 12-48 hours; 24.9% had delirium, 36.5% had dementia, and 16.7% were comorbid.

Although both EF and PR signs were present to some extent in all study groups, their frequency was significantly higher in those with delirium than in control groups.

Results “suggest the importance of a simple physical examination for these signs as an additional assessment for delirium presence, even in patients who have known or unknown preexistingdementia,” say the researchers. “Since prior longitudinal research suggests that incident delirium can be associated with a temporal increase in these types of signs, it may be an advantage to perform and record a baseline examination in all older patients who are medically ill or presenting for surgery and therefore at risk for delirium during hospitalization.”

  • The Delirium Frontal Index (©Franco and Trzepacz 2020 but no fee for not-for-profit use) based on this research can be downloaded here.

Psychosomatics journal cover

The full report, Discriminant Performance of Dysexecutive and Frontal Release Signs for Delirium in Patients With High Dementia Prevalence: Implications  for Neural Network Impairment, by José Franco, MS, MD, and colleagues, is in the January/February edition of JACLP.



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