Primitive reflexes in Alzheimer's disease and vascular dementia

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.

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.

Nociceptive Primitive Reflexes in Neurologically and Cognitively Healthy Aging Subjects

BACKGROUND

To assess the prevalence of three nociceptive primitive reflexes (nPR), i.e., glabellar tap, snout reflex, and palmomental reflex, in neurologically and cognitively healthy (NCH) aging subjects.

OBJECTIVE

To investigate whether nPR are cross-sectionally associated with white matter hyperintensities (WMH), lacunes, atrophy of the caudate nuclei, and global brain atrophy.

METHODS

A total of 1246 NCH subjects aged 45-91 years were included in the study and underwent standard brain MRI. Atrophy of the caudate nuclei and global brain atrophy were assessed through the bicaudate ratio (BCr) and lateral ventricles to brain ratio (LVBr), respectively. WMH were assessed through visual rating scales. Lacunes were also rated. Association of nPR with vascular risk factors/diseases and imaging findings was evaluated using logistic regression analysis.

RESULTS

nPR were exhibited by 33.1% of subjects and increased with age. Subjects with nPR performed less than subjects without nPR in tests evaluating global cognition, executive functions, attention, and language. Snout reflex was the most common nPR, followed by glabellar tap and palmomental reflex. Glabellar tap was associated with parieto-temporal WMH, BCr, and LVBr; snout reflex was associated with frontal lacunes, temporal WMH, BCr, and LVBr; palmomental reflex was associated with parieto-occipital WMH, basal ganglia lacunes, BCr, and LVBr.

CONCLUSIONS

This study demonstrates that in NCH aging individuals, nPR are associated with WMH, lacunes, BCr, and LVBr and are probably a warning sign of incipient cognitive decline. Therefore, NCH subjects presenting nPR should manage their vascular risk factors/vascular diseases rigorously in order to prevent or delay progression of small vessel disease, and future neurological and cognitive disabilities.

Neurological signs as early determinants of dementia and predictors of mortality among older adults in Latin America: a 10/66 study using the NEUROEX assessment

Background

Neurodegenerative processes in the elderly damage the brain, leading to progressive, incapacitating cognitive, behavioral, and motor dysfunctions which culminate in dementia. Fully manifest dementia is likely to be preceded by the presence of neurological signs, which could serve as early determinants of dementia and predictors of mortality. The aims of this study were to assess the construct validity of a neurological battery assessed among older adults living in Latin America, and to test the association of groups of neurological signs with dementia cross-sectionally, and mortality longitudinally.

Methods

The 10/66 Dementia Research Group collected information on neurological symptoms via the NEUROEX assessment in population based surveys of older adults living in low and middle-income countries. Data from 10,856 adults participating in the baseline assessment of the 10/66 study and living in Cuba, Dominican Republic, Peru, Venezuela and Mexico were analysed. Exploratory and confirmatory analysis were used to explore dimensionality of neurological symptoms. Poisson regression analyses were used to link groups of neurological signs with dementia at baseline. Cox hazard regression models were used to explore the predictive validity of neurological signs with mortality at follow up.

Results

Exploratory and confirmatory factor analyses revealed four dimensions of neurological signs, which are associated with lesions of specific brain regions. The identified factors showed consistency with groups of neurological signs such as frontal, cerebellar, extrapyramidal, and more generalized gait disturbance signs. Regression analyses revealed that all groups of neurological signs were positively associated with dementia at baseline and predicted mortality at follow up.

Conclusions

Our findings support the construct and predictive validity of the NEUROEX assessment, linking neurological and gait impairments with dementia at baseline, and with mortality at follow up among older adults living in five Latin American countries.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1167-4) contains supplementary material, which is available to authorized users.

Neonatal imitation in context: Sensorimotor development in the perinatal period

More than 35 years ago, Meltzoff and Moore (1977) published their famous article, “Imitation of facial and manual gestures by human neonates.” Their central conclusion, that neonates can imitate, was and continues to be controversial. Here, we focus on an often-neglected aspect of this debate, namely, neonatal spontaneous behaviors themselves. We present a case study of a paradigmatic orofacial “gesture,” namely tongue protrusion and retraction (TP/R). Against the background of new research on mammalian aerodigestive development, we ask: How does the human aerodigestive system develop, and what role does TP/R play in the neonate's emerging system of aerodigestion? We show that mammalian aerodigestion develops in two phases: (1) from the onset of isolated orofacial movementsin uteroto the postnatal mastery of suckling at 4 months after birth; and (2) thereafter, from preparation to the mastery of mastication and deglutition of solid foods. Like other orofacial stereotypies, TP/R emerges in the first phase and vanishes prior to the second. Based upon recent advances in activity-driven early neural development, we suggest a sequence of three developmental events in which TP/R might participate: the acquisition of tongue control, the integration of the central pattern generator (CPG) for TP/R with other aerodigestive CPGs, and the formation of connections within the cortical maps of S1 and M1. If correct, orofacial stereotypies are crucial to the maturation of aerodigestion in the neonatal period but also unlikely to co-occur with imitative behavior.

Detecting dementia in patients with normal neuropsychological screening by Short Smell Test and Palmo-Mental Reflex Test: an observational study

Background

General practitioners (GPs) are in best position to suspect dementia. Mini-Mental State Examination (MMSE) and Clock Drawing Test (CDT) are widely used. Additional neurological tests may increase the accuracy of diagnosis. We aimed to evaluate diagnostic ability to detect dementia with a Short Smell Test (SST) and Palmo-Mental Reflex (PMR) in patients whose MMSE and CDT are normal, but who show signs of cognitive dysfunction.

Methods

This was a 3.5-year cross-sectional observational study in the Memory Clinic of the University Department of Geriatrics in Bern, Switzerland. Participating patients with normal MMSE (>26 points) and CDT (>5 points) were referred by GPs because they suspected dementia. All were examined according to a standardized protocol. Diagnosis of dementia was based on DSM-IV TR criteria. We used SST and PMR to determine if they accurately detected dementia.

Results

In our cohort, 154 patients suspected of dementia had normal MMSE and CDT test results. Of these, 17 (11 %) were demented. If SST or PMR were abnormal, sensitivity was 71 % (95 % CI 44–90 %), and specificity 64 % (95 % CI 55–72 %) for detecting dementia. If both tests were abnormal, sensitivity was 24 % (95 % CI 7–50 %), but specificity increased to 93 % (95 % CI 88–97 %).

Conclusion

Patients suspected of dementia, but with normal MMSE and CDT results, may benefit if SST and PMR are added as diagnostic tools. If both SST and PMR are abnormal, this is a red flag to investigate these patients further, even though their negative neuropsychological screening results.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-015-0094-0) contains supplementary material, which is available to authorized users.

The grasp reflex: a symptom in need of treatment

The grasp reflex is one of the primitive reflexes frequently observed in neurodegenerative diseases. However, quality of life and treatment of the grasp reflex are neglected in the literature. Following two brief case vignettes of patients seen recently who experienced disability from a grasp reflex, we briefly review its phenomenology, anatomy-physiology and epidemiology in neurodegenerative movement disorders, and assess the limited current literature regarding the quality of life and treatment.

Primitive reflex evaluation in the clinical assessment of extrapyramidal syndromes

The aim of the present study was to evaluate the role of primitive reflexes (PRs) as additional alert sign in routine clinical practice in patients with extrapyramidal syndrome. We considered glabellar, snout, palmomental and grasp reflexes in patients with mild stage of Lewy body dementia (LBD), corticobasal degeneration, progressive supranuclear palsy or Parkinson disease (PD). We also enrolled mild Alzheimer disease (AD) patients, and healthy subjects, as controls. LBD patients showed the highest prevalence of PRs compared with the other groups. The odds ratio of the risk of LBD in PRs > or = 2 was 27.9 (95% CI 2.9-269.0) compared with control group, 14.6 (95% CI 2.7-79.6) compared with mild AD, and 19.7 (95% CI 3.7-104.3) compared with PD. These data suggest that the occurrence of combination of PRs might be an useful additional warning sign of possible diffuse Lewy body pathology more than other causes of extrapyramidal syndrome.

Prevalence of primitive reflexes and the relationship with cognitive change in healthy adults

OBJECTIVES

Primitive reflexes (PR) generally disappear early in life but may reappear later, in which case they are often associated with chronic neurological conditions, such as dementia or Parkinson's disease. Studies have shown that the presence of PRs may be indicative of both the severity and rate of progression of these diseases and may be the result of disinhibition of cortical networks. The association between PRs and cognitive function in usual ageing is unclear. We investigated whether the occurrence, amplitude, and persistence of four nociceptive (glabbelar tap, palmomental, pollicomental, and snout reflexes), three prehensile reflexes (suck, palmar grasp, and rooting), and two other reflexes (mouth open finger-spread and nuchocephalic reflexes) were related to performance in specific cognitive domains in normal ageing individuals.

METHODS

Four-hundred and seventy normal aging participants (25-82 years) in the Maastricht Aging Study (MAAS), were included in the study. They were neurologically and cognitively screened at baseline and were retested after 3 (only individuals aged 50 years and older at baseline) and 6 years.

RESULTS

The prevalence of most PRs increased with age: 47% of men aged 25-45 years had at least one PR, compared with 73% of men aged 65-85 year (p = 0.002). In women these percentages were 51 and 75, respectively (p=0.008). The prevalence, amplitude, and persistence of PRs were unrelated to cognition at baseline or at the 3- or 6-year follow-up.

CONCLUSIONS

The prevalence of particularly nociceptive reflexes rises substantially with increasing age in normal individuals. However, the presence of PRs cannot be considered to be a marker of cognitive decline in normal aging individuals.

Cortical release signs in psychiatry

OBJECTIVE

To review the role of cortical release signs (CRS) in neuropsychiatry.

METHOD

A thorough literature review was conducted using Medline and Psychlit databases, and other relevant references available to the authors.

RESULTS

A number of neurological abnormalities are reported at elevated rates in neuropsychiatric conditions. CRS are a group of primitive reflexes that are present in the neonate but become inhibited as the infant central nervous system (CNS) develops, only to later re-emerge in the context of CNS disease. The clinical elicitation and interpretation of each CRS is described with reference to its neurobiology. The prevalence of CRS in schizophrenia, affective disorder, obsessive-compulsive disorder, Alzheimer's disease, vascular dementia, frontotemporal dementia and other neuropsychiatric illness allows for their use in the clinical management of these patients, including diagnostic assessment, treatment monitoring and prognosis.

CONCLUSIONS

A number of issues complicate their interpretation in neuropsychiatric illness, including the apparent high base rate of some CRS in non-clinical populations, their increasing prevalence with age, lack of specificity and uncertainty over what constitutes an 'abnormal' response. In some circumstances, CRS may assist in diagnostic differentiation and illness staging.

The palmomental reflex: a useful clinical sign?

The palmomental reflex, an involuntary contraction of the mentalis muscle of the chin caused by stimulation of the thenar eminence, can be tested easily and rapidly. Its presence may alert the clinician to the possibility of cerebral pathology. However, the reflex is often present in normal people and may be absent in disease states. Testing merely for the presence or absence of the reflex therefore lacks both specificity and sensitivity. A strong, sustained, and easily repeatable contraction of the mentalis muscle, which can be elicited by stimulation of areas other than the palm, is more likely to indicate cerebral damage.

The Acute versus Chronic Pain Questionnaire (ACPQ) and actual pain experience in older people

The Acute versus Chronic Pain Questionnaire (ACPQ) was applied to older people. Two groups emerged from an analysis of which an item of each pair (an acute and a chronic affective item) was considered to cause the most suffering. One group of subjects comprised those who expected to suffer more from one or more acute pain items (high-ACPQ group, n = 35). A second group emerged for whom none of the acute items was considered to be a burden (low-ACPQ group, n = 33). It was hypothesized that, compared to the low-ACPQ group, the subjects with high-ACPQ scores selected acute ACPQ-items due to a decline in the experience of chronic affective pain. This hypothesis predicted lower scores on the chronic ACPQ-items and lower scores on scales evaluating the subjects' own chronic affective pain. The results showed that, irrespective of the group, the chronic ACPQ-items were considered to produce the most burdens. However, compared with the low-ACPQ group, the high-ACPQ group reported experiencing significantly more pain from the acute ACPQ-items. Moreover, the latter group indicated suffering less pain from their own chronic pain conditions. The present findings suggest that the selection of one or more acute items of the ACPQ (high-ACPQ group) may point to an alteration in subjects' actual pain experience.

Assessment and understanding of pain in patients with dementia

The literature on pain in dementia patients is reviewed. A summary of methods for assessment of pain in demented elderly persons and an examination of studies that used such methods are included. In addition, literature theorizing a decrease in affective pain in this population is discussed; management of pain in such patients is not discussed extensively. Research reveals 3 major findings: (a) a moderate decrease in pain occurs in cognitively impaired elderly persons, (b) communicative dementia patients' reports of pain tend to be as valid as those of cognitively intact patients, and (c) assessment scales developed thus far for noncommunicative patients require improvement in accuracy and facility. Many questions about pain in dementia patients remain, and the continued development of valid pain assessment techniques is a necessity.