The Relative Sensitivity Of An Olfactory Identification Deficit In Individuals With Schizotypal Personality Features

Olfactory identification deficits have received recent attention as a potentially useful endophenotype for schizophrenia. Examination of this deficit in individuals with schizotypal personality features (SPF) offers an alternative approach to multiple confounds present when examining individuals with schizophrenia. The aim of the current study was to compare the relative sensitivity of performance on measures of olfaction identification and sustained attention to the presence of SPF. Twenty-six undergraduates were defined as having SPF based on scoring in the top 10% of the Abbreviated Schizotypal Personality Questionnaire (SPQ-B; mean age 19.6, SD = 1.1; 62% female). These individuals were compared to twenty-six controls (scoring lower than half a standard deviation above the mean; mean age 19.8, SD = 1.6; 62% female). All participants were administered the Schizotypal Personality Disorder (SPD) section of the Structured Clinical Interview for DSM IV Axis II Personality Disorders (SCID-II). In addition, participants were administered the Brief Smell Identification Test (B-SIT) and a six-minute degraded-stimuli Continuous Performance Test (CPT). Group differences in performance indices of the CPT did not approach statistical significance. Similarly, there were no statistically significant group differences for males or females in performance on the B-SIT. Correlational analyses examined cognitive performance with a dimension score derived by summing quantitative ratings from the SPD items on the SCID-II. The SPD dimension score showed a statistically significant positive correlation with several performance indices of the CPT, including omission errors (rs(52) = .51, p ≤ .001) and commission errors (rs(52) = .38, p ≤ .005). In contrast, the B-SIT scores were not correlated with the SPD dimension score for males or females. Contrary to our hypothesis, results from the current study suggest that olfactory identification deficits may not represent a robust endophenotype consistently found in samples with schizotypal personality features. With regard to sustained attention, our differential findings suggest that schizotypal traits may be more adequately assessed through an interview by trained clinicians who use clinical judgment to determine the presence of phenotypic aspects of SPD (e.g., SCID-II), rather than relying on self-report measures (e.g., SPQ-B). Implications as well as limitations and future directions of these findings are discussed

Association Between Unirhinal Olfactory Processing And Self-reported Empathy In Schizophrenia

Empathy represents one multifaceted component of social cognition that is thought to be significantly impaired in individuals with schizophrenia. Psychophysical tasks of smell identification and hedonic processing of pleasant, neutral, and unpleasant odors share common neural networks involved in empathy. Therefore, we investigated the relationship between odor identification, odor ratings, and self-reported empathy in 25 outpatients with schizophrenia and 25 nonpsychiatric individuals. Group differences on empathy scores and unirhinal smell identification performance (with hedonic and intensity ratings) were examined, along with the relationships between smell identification scores, self-reported empathy, and schizophrenia symptomatology. The preliminary findings suggest that individuals with schizophrenia display significant differences from controls on measures of self-reported empathy, odor identification, and hedonic ratings of odors. Deficits in self-reported global and affective empathy were influenced by group and sex, whereas cognitive empathy was reduced across all patients in comparison to controls. Patients displayed reduced unirhinal odor identification accuracy for pleasant but not neutral or unpleasant odors in comparison to controls. Central to the overall aim of the current study, a robust positive correlation was observed between left- and right-nostril hedonic ratings for pleasant odors and self-reported global and affective empathy scores across all participants. In patients, we also found a statistical trend between affective empathy and left-nostril identification accuracy across all odors. Collectively, the results lend support to the role of olfactory-limbic brain regions in the hedonic processing of odors and suggest that aberrant performance observed in schizophrenia may be related to abnormalities in the anatomical and physiological substrates that also subserve empathy

Olfactory Identification Performance In Individuals With Psychometrically-Defined Schizotypy

While deficits in olfaction have been well documented in individuals with schizophrenia, less research has focused on olfactory identification performance in psychometrically-defined schizotypy. The Abbreviated Schizotypal Personality Questionnaire was used to define two groups of 26 individuals (62% female) reporting high and average levels of schizotypy. Overall group differences on the Brief Smell Identification Test did not approach statistical significance, and this finding did not differ within either sex. The findings may reflect either the abbreviated nature of the measures used, or a lack of reliable olfactory performance differences in schizotypy

Comparison Of Three Computer-Administered Cognitive Tasks As Putative Endophenotypes Of Schizophrenia

It has been repeatedly demonstrated that individuals with schizotypal personality features (SPF) exhibit similar endophenotypic traits as persons with schizophrenia. Less research has compared the relative sensitivity of different endophenotypes in the same sample of individuals with SPF. Fourteen university students with SPF (mean age 20.5 ± 1.6; 43% male) and 26 controls (mean age 20.3 ± 1.1; 31% male) were defined by the Abbreviated Schizotypal Personality Questionnaire (SPQ-B). All participants reported no known biological relative with schizophrenia. Participants completed three computer-administered cognitive tasks: a 6-min degraded-stimuli A-X Continuous Performance Test (CPT), the Wisconsin Card Sort Test (WCST), and a Span of Apprehension (SOA) task (6- and 12-letter arrays). On the CPT, only omission errors resulted in a statistically significant group difference, U = 115.5, p = .05, Cohen\u27s d = 0.54 (medium effect size), with the SPF group (mean errors: 3.43 ± 3.28) making more omission errors than controls (mean errors: 1.88 ± 2.66). Notably, 46% of the controls had no omission errors, compared to 14% of the SPF group. The only SPQ-B factor score to show a statistically significant linear relationship with CPT omission errors was the Cognitive-Perceptual factor (rs = .33, p = .04). Group differences on performance indices from the SOA and WCST did not approach statistical significance. Based on performance from the community-identified schizotypes, results suggest that performance on the CPT may represent a more robust endophenotype of schizophrenia, compared to the SOA and WCST. © 2006 Elsevier B.V. All rights reserved

Is The Odour Identification Deficit In Schizophrenia Influenced By Odour Hedonics?

Introduction. While smell identification deficits have been well documented in schizophrenia, less work has examined identification accuracy for pleasant and unpleasant odours. The current investigation examined odour identification performance for pleasant and unpleasant odours in a sample of inpatients with schizophrenia and nonpsychiatric community controls. Method. The Brief Smell Identification Test was used to investigate accuracy in the identification of pleasant and unpleasant odours in 23 schizophrenia inpatients and 21 nonpsychiatric controls. Results. Results revealed that schizophrenia patients showed reduced accuracy on pleasant odours, but intact performance for unpleasant odours. Conclusions. Results provide preliminary support for a specific deficit in identifying pleasant odours in patients with schizophrenia. Future studies separating odours by valence categories are warranted. © 2011 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

The Relationship Between Interview-Based Schizotypal Personality Dimension Scores And The Continuous Performance Test

The existing research that has examined cognitive performance in samples with subclinical schizotypal personality features has been largely limited to psychometric self-report questionnaires, which may be biased by distorted self-awareness of symptoms. The present study examined the relationship between performance on a degraded-AX continuous performance test (CPT) and continuous dimension scores created from a structured clinical interview for schizotypal personality disorder (SPD), which reflected both the breadth and severity of schizotypal personality symptoms, in 52 undergraduate students. Only one participant met full diagnostic criteria for SPD. The overall dimension score from the SPD clinical interview showed a positive correlation with both omission (rs = .47) and false alarm (rs = .41) errors on the CPT. Interpersonal symptoms were positively correlated with omission errors (rs = .47), while Disorganized symptoms were positively correlated with false alarm errors (rs = .40). Results suggest that higher SPD interview-based dimension scores are associated with lower levels of performance on the CPT, even when examining a relatively subclinical sample of young adults. In contrast, scores from the psychometric Abbreviated Schizotypal Personality Questionnaire in the same sample did not correlate with accuracy measures on the CPT, suggesting that the interview-based measure of schizotypal personality may have a stronger relationship with CPT accuracy. Findings also add to a growing literature suggesting that Interpersonal SPD symptoms are primarily related to omission errors, while Disorganized SPD symptoms are primarily related to false alarm errors. © 2008 Elsevier B.V. All rights reserved

Potential Role for Diet in Mediating the Association of Olfactory Dysfunction and Cognitive Decline: A Nationally Representative Study

In the context of a growing body of evidence associating olfactory dysfunction (OD) with cognitive decline, this cross-sectional study used data from the 2013–2014 National Health and Nutrition Examination Survey (NHANES) sample in order to explore the role of dietary intake in this association. Leveraging a nationally representative sample of U.S. adults aged 60 years and older, this study analyzed dietary patterns using exploratory factor analysis. OD was categorized based on the NHANES Pocket Smell Test, and cognitive function was measured with a battery of tests. Survey-weighted multivariable regressions and causal mediation analysis were used to examine the relationship between dietary patterns, OD, and cognitive function. Results indicated that a poor adherence to a diet rich in monounsaturated fats (MUFAs) and polyunsaturated fats (PUFAs) was independently associated with both cognitive and olfactory dysfunctions, after adjusting for sociodemographic and health factors. Moreover, the relationship between OD and cognitive decline was found to be partly mediated by adherence to such a diet. This study proposes a potential link between diet, olfactory function, and cognitive decline, highlighting the role of nutritional interventions in mitigating cognitive decline, particularly in individuals with olfactory impairment

Odor Hedonic Capacity and Anhedonia in Schizophrenia and Unaffected First- Degree Relatives of Schizophrenia Patients

Objective: There is increasing evidence that schizophrenia patients have difficulties in the hedonic appraisal of odors. In a prior study, we assessed olfactory hedonic perception birhinally and found that males with schizophrenia failed to attach the appropriate hedonic valence to a pleasant odor, despite correctly perceiving changes in odor intensity. Female patients, in contrast, exhibited normal responses. The current study extends this work by examining odor valence processing in unaffected first-degree relatives of schizophrenia patients, to determine the extent to which this abnormality may be genetically mediated. We also examine odor valence processing unirhinally, rather than birhinally, to probe possible lateralized differences in patients' hedonic processing deficits. Method: Individuals with schizophrenia (n 5 54), first-degree unaffected family members (n 5 22), and demographically matched controls (n 5 45) were administered the Suprathreshold Amyl Acetate Odor Intensity and Odor Pleasantness Rating Test. Results: In contrast to family members and controls, both male and female schizophrenia probands underevaluated the hedonic characteristics of amyl acetate at lower concentrations and overevaluated its pleasantness at concentrations perceived as unpleasant by both controls and relatives. These patient-specific differences could not be explained by differences in smoking habit, medication use, or subjective ratings of odor intensity. However, they were associated with increased levels of anhedonia/asociality and negative symptomatology. Conclusions: Our findings suggest that both male and female schizophrenia patients have difficulties in the unirhinal appraisal of hedonic valence. Normal responses in unaffected first-degree relatives suggest that this is an environmentally, rather than genetically, mediated abnormality denoting negative symptomatology

Association of Frailty Status and Dietary Patterns in a Nationally Representative Sample of United States Adults with Olfactory Dysfunction

Background: Olfactory dysfunction (OD) is a strong, independent predictor of frailty and mortality risk. This study evaluated the association of dietary patterns and frailty status in older adults with OD. Methods: This cross-sectional study utilized the 2013–2014 National Health and Nutrition Examination Survey. Dietary patterns (DPs) characteristic of OD were derived using exploratory factor analysis (EFA). Multiple logistic regressions adjusted for demographics and frailty risk factors assessed the association of DPs with two frailty metrics: the frailty index (FI) and physical frailty (PF). Results: EFA yielded six distinct DPs in persons with OD. The protein/selenium (OR 0.82 [95% CI 0.74–0.92], p = 0.041) and β-carotene/vitamin A DPs (OR 0.76 [95% CI 0.66–0.88], p = 0.028) were independently associated with frailty by FI. Only the protein/selenium DP (OR 0.82 [95% CI 0.74–0.92], p = 0.036) was associated with frailty by PF. No DPs were associated with either frailty measure in normosmic persons. Conclusions: Dietary patterns high in protein/selenium and β-carotene/vitamin A are associated with lower frailty prevalence in adults with OD. While the relationship between OD and frailty is likely multifaceted, these findings suggest that dietary patterns are uniquely associated with frailty in older adults with OD