Nociceptive Primitive Reflexes in Neurologically and Cognitively Healthy Aging Subjects

Primitive reflexes and dementia in older adults: a meta-analysis of observational and cohort studies

Primitive reflexes (PRs) are clinical signs that indicate diffuse cerebral dysfunction and frontal lesions. We aimed to present a comprehensive analysis of the prevalence and risk of PRs in patients with dementia. English-language articles published from January 1990 to April 2021 were searched in PubMed, ScienceDirect, Cochrane, and Web of Science with keywords. The titles and abstracts of the identified articles were screened to identify potentially relevant papers. Odds ratios and risk ratios were extracted with 95% confidence intervals and combined using the random-effects model after logarithmic transformation. The prevalence in dementia patients was also combined using the random-effects model. This meta-analysis involved 29 studies. The snout reflex (48% of cases) was the most prevalent. It was found that the risk of PRs in individuals with dementia was significantly elevated, ranging from 13.94 to 16.38 times higher than in healthy controls. The grasp reflex exhibited the highest risk for dementia. This meta-analysis showed that the prevalence and the risk of PRs is high in older patients with dementia. Therefore, PRs, especially the grasp reflex, should be carefully assessed as a part of routine physical examination in the diagnostic process for dementia.

Retained Primitive Reflexes and Potential for Intervention in Autistic Spectrum Disorders

We provide evidence to support the contention that many aspects of Autistic Spectrum Disorder (ASD) are related to interregional brain functional disconnectivity associated with maturational delays in the development of brain networks. We think a delay in brain maturation in some networks may result in an increase in cortical maturation and development in other networks, leading to a developmental asynchrony and an unevenness of functional skills and symptoms. The paper supports the close relationship between retained primitive reflexes and cognitive and motor function in general and in ASD in particular provided to indicate that the inhibition of RPRs can effect positive change in ASD.

Discriminant Performance of Dysexecutive and Frontal Release Signs for Delirium in Patients With High Dementia Prevalence: Implications for Neural Network Impairment

BACKGROUND

Prevalence of signs of abnormal executive function (EF) and primitive reflexes (PR) with delirium in older hospitalized patients with or without comorbid dementia has not been reported.

OBJECTIVE

To describe prevalence of signs of EF deficits and PR in older inpatients and their discriminant value for delirium while accounting for dementia.

METHODS

Participants were evaluated for delirium using the Diagnostic and Statistical Manual of Mental Disorders 5th edition and the Delirium Rating Scale Revised-98, dementia using Informant Questionnaire on Cognitive Decline in the Elderly, and signs of PR (n = 5) and EF deficits (n = 3) using bedside neuropsychiatric examination. Three indices (PR, EF, and Combined) and 4 diagnostic groups were created for correlational and discriminant analyses.

RESULTS

Correlations of indices were higher with the Delirium Rating Scale Revised-98 than with the Informant Questionnaire on Cognitive Decline in the Elderly and even higher in those with dementia, especially the Combined index (Delirium Frontal Index). Among individual signs, glabellar and Simple Luria Hand Sequence were most common in delirium and the best for delirium discrimination irrespective of dementia status. The Combined index had about 80% sensitivity and specificity at the ≥2 cutoff in the whole cohort (positive and negative predictive values and likelihood ratios: PPV 50.0%, NPV 93.8%, +LR 3.82, -LR 0.25). The Combined index also had the best performance on discriminating delirium in dementia patients at the ≥3 cutoff, with about 80% for both sensitivity and specificity.

CONCLUSIONS

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. We recommend simple bedside assessment of PR and EF signs to help assess for delirium as an indicator of cerebral cortical neural network impairment in older persons.

Isolated, Subtle Neurological Abnormalities in Mild Cognitive Impairment Types

BACKGROUND

Isolated, subtle neurological abnormalities (ISNA) are commonly seen in aging and have been related to cerebral small vessel disease (SVD) and subcortical atrophy in neurologically and cognitively healthy aging subjects.

OBJECTIVE

To investigate the frequency of ISNA in different mild cognitive impairment (MCI) types and to evaluate for each MCI type, the cross-sectional relation between ISNA and white matter hyperintensities (WMH), lacunes, caudate atrophy, and ventricular enlargement.

METHODS

One thousand two hundred fifty subjects with different MCI types were included in the analysis and underwent brain magnetic resonance imaging. WMHs were assessed through two visual rating scales. Lacunes were also rated. Atrophy of the caudate nuclei and ventricular enlargement were assessed through the bicaudate ratio (BCr) and the lateral ventricles to brain ratio (LVBr), respectively. Apolipoprotein E (APOE) genotypes were also assessed. The routine neurological examination was used to evaluate ISNAs that were clustered as central-based signs, cerebellar-based signs, and primitive reflexes. The items of Part-III of the Unified Parkinson's Disease Rating Scale were used to evaluate ISNAs that were clustered as mild parkinsonian signs. Associations of ISNAs with imaging findings were determined through logistic regression analysis.

RESULTS

The ISNAs increase with the age and are present in all MCI types, particularly in those multiple domains, and carrying the APOE ϵ4 allele, and are associated with WMH, lacunes, BCr, and LVBr.

CONCLUSION

This study demonstrates that cortical and subcortical vascular and atrophic processes contribute to ISNAs. Long prospective population-based studies are needed to disentangle the role of ISNAs in the conversion from MCI to dementia.