An examination of semantic performance in mild cognitive impairment progressors and nonprogressors.

OBJECTIVE: Mild cognitive impairment (MCI) is a risk factor for developing Alzheimer's disease (AD), and about half of older people with MCI will progress to AD within the next 5 years. The aim of the present study was to compare the semantic performance of MCI progressors (MCI-p) and nonprogressors (MCI-np). The hypothesis was that MCI-p would present with poorer semantic performance relative to MCI-np at baseline, indicating that semantic deficits may increase the risk of future decline toward AD. METHOD: Fifty-six MCI participants (aged 65-89) from the Consortium for Early Identification of Alzheimer's Disease-Quebec study were analyzed, with 18 progressing and 38 remaining stable over 2 years. Analysis of covariance assessed their initial semantic and nonsemantic cognitive performance, and mixed analyses of variance gauged longitudinal patterns of cognitive decline at the 2-year follow-up. RESULTS: In the semantic domain, MCI-p performed significantly worse than MCI-np at baseline on two semantic tests (category fluency and object decision). In other cognitive domains, MCI-p performed worse than MCI-np on a test of executive functions (cognitive flexibility) but showed similar performance on a test of episodic memory. There were no significant differences between groups in the rates of progression on semantic tests over the 2-year period, but a steeper decline was observed in MCI-p at follow-up on tests of global cognition, episodic memory, and processing speed. CONCLUSION: This suggest that MCI patients who present with semantic memory impairment in addition to episodic memory impairment are at greater risk of future progression to AD. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Olfaction and declarative memory in aging: a meta-analysis.

Olfactory and declarative memory performances are associated, as both functions are processed by overlapping medial-temporal and prefrontal structures and decline in older adults. While a decline in olfactory identification may be related to a decline in declarative memory, the relationship between olfactory detection threshold and declarative memory remains unclear. In this meta-analysis, we assessed (i) the relationship between olfactory identification/detection threshold and verbal declarative memory in cognitively normal older adults, and (ii) the effect of age on these relationships. We included articles from PsychNet, PubMed, and Academic Search Complete according to the following criteria: (i) inclusion of cognitively normal older adults; (ii) assessment of episodic or semantic memory; and (iii) assessment of olfactory identification or detection threshold. Seventeen studies and 22 effect sizes were eligible and included in this meta-analysis. Olfactory identification was associated with episodic (small effect size: r = 0.19; k = 22) and semantic memory (small effect size: r = 0.16; k = 23). Similarly, the olfactory detection threshold was associated with both episodic (small to medium effect size: r = 0.25; k = 5) and semantic memory (small effect size: r = 0.17; k = 7). Age was found to moderate the relationship between olfactory detection threshold and memory performance. Both olfactory identification and detection threshold performances are associated with declarative memory in older adults, and age only moderates the relationship between olfactory detection threshold and declarative memory performances.

A quick test to objectify smell and taste dysfunction at home: a proof of concept for the validation of the chemosensory perception test.

Recent studies have shown the efficacy of a home test for the self-evaluation of olfactory and gustatory functions in quarantined coronavirus disease-2019 (COVID-19) patients. However, testing was often limited to COVID-19 participants, and the accuracy of home test kits was rarely compared to standardized testing. This study aims at providing proof of concept for the validation of the new Chemosensory Perception Test (CPT) developed to remotely assess orthonasal olfactory, retronasal olfactory, and gustatory functions in various populations using common North American household items. In the 2 experiments, a total of 121 participants irrespective of having olfactory and/or gustatory complaints from various causes (COVID-19, sinunasal, post-viral, idiopathic) were tested first, with one or many of the following tests: (i) a brief chemosensory questionnaire, (ii) an olfactory test-Sniffin' Sticks Test (SST) or University of Pennsylvania Smell Identification Test (UPSIT), and/or (iii) a gustatory test-Brief Waterless Empirical Taste Test (B-WETT). We then applied the CPT which yielded 3 different subscores, namely orthonasal, retronasal, and gustatory CPT scores. The orthonasal CPT score was significantly correlated with SST (ρ = 0.837, P < 0.001) and UPSIT (ρ = 0.364, P < 0.001) scores, and exhibited an excellent accuracy to identify olfactory dysfunction (OD) as compared to SST (area under the curve [AUC]: 0.923 [95% confidence interval {CI}, 0.822-1.000], P < 0.001). The retronasal CPT score but not the gustatory CPT score allowed to distinguish between participants with or without subjective gustatory complaint (AUC: 0.818 [95% CI, 0.726-0.909], P < 0.001). The CPT has the ability to identify OD and to quantify subjective gustatory complaints.

Decreased self-reported appetite following insular cortex resection in patients with epilepsy.

Entrenched deep within the Sylvian fissure, the insula has long been considered one of the least understood regions of the human brain, in part due to its restricted accessibility. However, recent evidence suggests that the insula plays a key role in gustation, interoception, cognitive and emotional processes, and likely integrates these different functions to contribute to the homeostatic control of food intake. In the past decade, our team has identified the insula as a potential site of epileptogenicity, which can be successfully treated by microsurgical resection. While most surgeries are successful in controlling insular epileptic seizures and lead to few postoperative deficits, the subtle changes that may occur in food-related experiences are still unknown. Using a self-report questionnaire, the present study sought to fill this gap by assessing changes in appetite in patients who underwent unilateral partial or complete insular resections (n = 17) as part of their epilepsy surgery. We compared them to a group of patients who underwent temporal lobe epilepsy surgery (n = 22) as a lesion-control group. A majority (59%) of the insular patients reported an alteration in appetite, with most of these changes being characterized by a persistent reduction. Such changes were rarely reported following temporal lobectomy (14%). While they significantly differed in terms of appetite changes, both groups were similar when examining post-surgical changes in weight, diet, exercise and eating habits. Insular patients with altered appetite also showed behavioral signs of dysfunctional interoceptive and gustatory functions, corroborating the idea that these systems play a role in the regulation of feeding behaviours. This research pushes our understanding of the mechanisms underlying food intake and could lead to avenues for the treatment of eating disorders.

Insula and Olfaction: A Literature Review and Case Report.

(1) Background: It is well established that the insula is involved in olfaction, though its specific role in olfactory processing remains uncertain. In this paper, we first review the current literature on the insula and olfaction. Then, we describe the case of a 56-year-old man with a left insular cavernoma that caused olfactory disturbances. (2) Results: Structural neuroimaging studies suggest that insular gray matter volume is related to olfactory function, and functional neuroimaging shows that various types of stimuli lead to either lateralized or bilateral insular activations. Studies using electro-cortical stimulation reveal a specific region of the insular cortex, around the central insular sulcus, that could be related to unpleasant odor processing. Previous cases of insular lesions leading to olfactory disturbances suggest that left-sided insular lesions may more frequently lead to olfactory changes. In our patient with a left insular cavernoma, odors that were previously perceived as pleasant started smelling unpleasant and were hard to distinguish. Despite these subjective complaints, olfactory function assessed with the Sniffin' Sticks test was normal. (3) Conclusions: Current tests may not be sensitive to all types of olfactory impairments associated with insular damage, and further studies should be conducted to develop olfactory tests assessing the hedonic appreciation of odors.

Sensory profile alterations in patients with insular epilepsy surgery: Preliminary findings.

The insular cortex is now well-established as a potential site of epileptogenesis in patients with drug-resistant epilepsy, and its resection has been associated with good outcomes in terms of seizure control. However, given the role of the insula in sensory processing and in visceral information integration, it remains unclear whether insular cortex epilepsy and its surgery are associated with disturbances in sensory information processing and visceral sensation processes as experienced in daily life. In the present study, we examined such sensory disturbances in a group of patients (n = 17) who underwent epilepsy surgery involving a resection of the insula and compared them to a lesion-control group of patients with temporal epilepsy surgery (n = 22) and a healthy control group (n = 29) matched for age, gender, and education. Participants were assessed on the self-report "Adolescent/Adult Sensory Profile" questionnaire at least four months after surgery. Our series of one-way analyses of variance (ANOVAs) revealed that insular and temporal resections in patients with drug-refractory epilepsy were associated with a low "sensation seeking" behavior reflecting a lack of engagement with sensory inputs from the environment. Furthermore, insular resections were associated with impairments in the "active behavioral responses" for the gustatory/olfactory modalities. These preliminary findings suggest that insular resections may be associated with mild to moderate alterations in sensory processing.

The effects of insular and mesiotemporal lesions on affective information processing: Preliminary evidence from patients with epilepsy surgery.

Depressive symptoms and anxiety are common complaints in patients who have had epilepsy surgery. Recent studies have reported disturbances in emotional memory, facial and vocal emotion recognition, and affective learning after temporal lobe and/or insular resection for drug-resistant seizures, suggesting that these regions may be involved in emotional processes underlying psychological symptoms. The insula is a core component of the salience network and is thought to be involved in processing emotions such as disgust, and the role of mesial temporal lobe structures in affective processing is well established. However, to our knowledge, no study has yet investigated whether attentional processing of affective information is altered when these structures are resected as part of an epilepsy surgery. The present study examined the interference control capacity and attentional biases for emotional information in adult patients with epilepsy who underwent temporal lobe resections including the amygdala and hippocampus (n = 15) and/or partial or complete insular resections (n = 16). Patients were tested on an Emotional Stroop test and on a Dot-Probe task using fearful and disgusting pictures and were compared with a healthy control group (n = 30) matched for age, gender, and education. Repeated-measures analyses of variances revealed a significant effect of emotional words on color naming speed in the Emotional Stroop task among insular patients, which was not observed in the other groups. By contrast, the groups did not differ on Dot-Probe task performance. These preliminary findings suggest that insular damage may alter emotional interference control.