Global study of social odor awareness

Olfaction plays an important role in human social communication, including multiple domains in which people often rely on their sense of smell in the social context. The importance of the sense of smell and its role can however vary inter-individually and culturally. Despite the growing body of literature on differences in olfactory performance or hedonic preferences across the globe, the aspects of a given culture as well as culturally universal individual differences affecting odor awareness in human social life remain unknown. Here, we conducted a large-scale analysis of data collected from 10,794 participants from 52 study sites from 44 countries all over the world. The aim of our research was to explore the potential individual and country-level correlates of odor awareness in the social context. The results show that the individual characteristics were more strongly related than country-level factors to self-reported odor awareness in different social contexts. A model including individual-level predictors (gender, age, material situation, education and preferred social distance) provided a relatively good fit to the data, but adding country-level predictors (Human Development Index, population density and average temperature) did not improve model parameters. Although there were some cross-cultural differences in social odor awareness, the main differentiating role was played by the individual differences. This suggests that people living in different cultures and different climate conditions may still share some similar patterns of odor awareness if they share other individual-level characteristics

Preferred interpersonal distances: a global comparison

Human spatial behavior has been the focus of hundreds of previous research studies. However, the conclusions and generalizability of previous studies on interpersonal distance preferences were limited by some important methodological and sampling issues. The objective of the present study was to compare preferred interpersonal distances across the world and to overcome the problems observed in previous studies. We present an extensive analysis of interpersonal distances over a large data set (N = 8,943 participants from 42 countries). We attempted to relate the preferred social, personal, and intimate distances observed in each country to a set of individual characteristics of the participants, and some attributes of their cultures. Our study indicates that individual characteristics (age and gender) influence interpersonal space preferences and that some variation in results can be explained by temperature in a given region. We also present objective values of preferred interpersonal distances in different regions, which might be used as a reference data point in future studies.info:eu-repo/semantics/publishedVersio

Human odor identification studied in healthy individuals, mild cognitive impairment and Alzheimer’s disease

Evnen til å identifisere lukter studert hos friske individer, personer med mild kognitiv svikt og Alzheimers sykdom Bakgrunn: Luktidentifikasjon er evnen til å oppfatte og navngi en lukt riktig. Allerede i midten av 1970-årene ble de første studiene publisert som viste at evnen til å lukte er svekket ved nevrodegenerative sykdommer (Ansari og Johnson og Waldton). Majoriteten av pasienter med amnestisk mild kognitiv svikt (aMCI) og tidlig Alzheimers sykdom er vist å få redusert lukteevnen, særskilt evnen til å identifisere lukter. Siden områder i hjernens temporallapp er sentral både i luktprosessering, samtidig som entorhinal cortex er det område som trolig rammes tidligst ved Alzheimers sykdom, så er det av stor interesse å undersøke lukteevnen hos denne pasientgruppen. For å vurdere nytten av testing med lukt identifikasjon i klinikken, trenger vi en bedre forståelse av de nevronale prosessene som ligger til grunn for lukt identifikasjon i den menneskelige hjerne. I tillegg trenger vi standardiserte luktetester for bruk i Norge som er tilpasset norske forhold. Dette bør være tester som er enkle å administrere, som koster lite og tar kort tid å gjennomføre. Formål: Denne avhandlingen har tre hovedmål. Det første målet var å undersøke nytten av kommersielle luktetester som "the Brief Smell Identification Test" (B-SIT), en modifisert versjon av B-SIT og "the Sniffin Sticks Identification Test" (SSIT) i norske populasjoner for å kunne skille pasienter med tidlig Alzheimers sykdom og aMCI fra friske kontroller. Det andre målet var å undersøke hvilke hjerneområder som aktiveres hos unge friske mennesker under vellykket identifisering av lukter. Det siste målet var å studere hvordan volumene av ulike strukturer i hjernen samvarierer med evnen til å identifisere lukter hos pasienter med mild grad av demens ved Alzheimers sykdom og friske sammenlignbare kontroller. Metoder: Artiklene i avhandlingen baserer seg på fire eksperimentelle studier i fire ulike populasjoner. Det er gjennomført psykofysiske luktetester i alle de fire populasjonene, men det er studiene referert i artikkel I og artikkel II som i hovedsak beskriver luktetestens metodikk. I artikkel III har vi brukt funksjonell magnetisk resonans bildedannelse (fMRI) for å studere aktiveringsmønsteret i hjernen ved luktidentifikasjon hos friske unge personer. Luktstimuleringen i skanneren ble gitt ved hjelp av et olfaktometer. I artikkel IV har vi brukt strukturell magnetisk resonans bildedannelse (strukturell MRI) for å studere assosiasjoner mellom volumer av ulike hjernestrukturer og evne til å identifisere lukter. Dette ble undersøkt hos pasienter med en aMCI og mild grad av demens ved Alzheimers sykdom og friske eldre personer. Hovedfunn: Studie I demonstrerer at B-SIT er velegnet for bruk i Norge til å skille pasienter med Alzheimers sykdom (hvor noen av pasientene var i tidlig stadium) fra friske personer. Studie II viser at en modifisert versjon av testen B-SIT, er en like god test som den originale B-SIT, samtidig som den trolig kan være en bedre test til bruk i generelle populasjoner. Funnene fra Studie III indikerer at entorhinal cortex og hippocampus er sentrale områder i hjernen som aktiveres spesifikt når friske unge personer klarer å identifisere lukter. Studie IV demonstrerer at pasienter med aMCI eller tidlig Alzheimers sykdom som har relativt intakt luktefunksjon (ut fra både B-SIT og SSIT), har større volum av hippocampus enn de med redusert luktidentifiseringsevne. Konklusjon: Våre funn viser at lukteskreening testene B-SIT og SSIT er godt tilpasset for bruk i Norge, og at en modifisert versjon av B-SIT vil være en like god test som den originale B-SIT. De nevronale prosessene som ligger til grunn for luktidentifikasjon i den menneskelige hjerne, ser ut til å inkludere et helt nettverk av strukturer, hvor særskilt entorhinal cortex og hippocampus er sentrale strukturer for at friske unge personer klarer å navngi lukter riktig. Luktetestene kan hjelpe til å skille ut de pasienter som er mer langtkommet i utviklingen av Alzheimers sykdom, fordi gruppen med redusert lukteidentifikasjonsevne hadde signifikant mer redusert hippocampus volum enn de med intakt lukteidentifikasjonsevne. Hva vi har funnet i studiene, har gitt økt kunnskap om nytten av bruk av luktetester i norske populasjoner, og ny kunnskap om de nevronale prosessene som ligger til grunn for luktidentifikasjon i den menneskelige hjerne

The Human Brain Representation of Odor Identification in Amnestic Mild Cognitive Impairment and Alzheimer's Dementia of Mild Degree

Background: Odor identification (OI) ability is a suggested early biomarker of Alzheimer’s disease. In this study, we investigated brain activity within the brain’s olfactory network associated with OI in patients with amnestic mild cognitive impairment (aMCI) and mild Alzheimer’s dementia (mAD) to uncover the neuronal basis of this impairment. Materials and Methods: Patients with aMCI (n = 11) or mAD (n = 6) and 28 healthy older adults underwent OI functional MRI (fMRI) at 3T, OI, odor discrimination, and cognitive tests and apolipoprotein-e4 (APOE4) genotyping. Eleven patients had cerebrospinal fluid (CSF) analyzed. Those with aMCI were followed for 2 years to examine conversion to dementia. Results: The aMCI/mAD group performed significantly worse on all OI tests and the odor discrimination test compared to controls. The aMCI/mAD group had reduced activation in the right anterior piriform cortex compared to the controls during OI fMRI [Gaussian random field (GRF) corrected cluster threshold, p < 0.05]. This group difference remained after correcting for age, sex education, and brain parenchymal fraction. This difference in piriform activity was driven primarily by differences in odor discrimination ability and to a lesser extent by OI ability. There was no group by odor discrimination/identification score interaction on brain activity. Across both groups, only odor discrimination score was significantly associated with brain activity located to the right piriform cortex. Brain activity during OI was not associated with Mini Mental Status Examination scores. At the group level, the aMCI/mAD group activated only the anterior insula, while the control group had significant activation within all regions of the olfactory network during OI fMRI. There was no association between brain activity during OI fMRI and total beta-amyloid levels in the CSF in the aMCI/mAD group. Conclusion: The OI impairment in aMCI/mAD patients is associated with significantly reduced activity in the piriform cortex compared to controls. Activation of downstream regions within the olfactory network is also significantly affected in the aMCI/mAD group, except the anterior insula, which is impinged late in the course of Alzheimer’s disease. OI tests thus reflect Alzheimer’s disease pathology in olfactory brain structures. Keywords: smell, olfaction, neurodegenaration, central nervous system (CNS), cognitio

The Human Brain Representation of Odor Identification in Amnestic Mild Cognitive Impairment and Alzheimer's Dementia of Mild Degree

Background: Odor identification (OI) ability is a suggested early biomarker of Alzheimer’s disease. In this study, we investigated brain activity within the brain’s olfactory network associated with OI in patients with amnestic mild cognitive impairment (aMCI) and mild Alzheimer’s dementia (mAD) to uncover the neuronal basis of this impairment. Materials and Methods: Patients with aMCI (n = 11) or mAD (n = 6) and 28 healthy older adults underwent OI functional MRI (fMRI) at 3T, OI, odor discrimination, and cognitive tests and apolipoprotein-e4 (APOE4) genotyping. Eleven patients had cerebrospinal fluid (CSF) analyzed. Those with aMCI were followed for 2 years to examine conversion to dementia. Results: The aMCI/mAD group performed significantly worse on all OI tests and the odor discrimination test compared to controls. The aMCI/mAD group had reduced activation in the right anterior piriform cortex compared to the controls during OI fMRI [Gaussian random field (GRF) corrected cluster threshold, p < 0.05]. This group difference remained after correcting for age, sex education, and brain parenchymal fraction. This difference in piriform activity was driven primarily by differences in odor discrimination ability and to a lesser extent by OI ability. There was no group by odor discrimination/identification score interaction on brain activity. Across both groups, only odor discrimination score was significantly associated with brain activity located to the right piriform cortex. Brain activity during OI was not associated with Mini Mental Status Examination scores. At the group level, the aMCI/mAD group activated only the anterior insula, while the control group had significant activation within all regions of the olfactory network during OI fMRI. There was no association between brain activity during OI fMRI and total beta-amyloid levels in the CSF in the aMCI/mAD group. Conclusion: The OI impairment in aMCI/mAD patients is associated with significantly reduced activity in the piriform cortex compared to controls. Activation of downstream regions within the olfactory network is also significantly affected in the aMCI/mAD group, except the anterior insula, which is impinged late in the course of Alzheimer’s disease. OI tests thus reflect Alzheimer’s disease pathology in olfactory brain structures. Keywords: smell, olfaction, neurodegenaration, central nervous system (CNS), cognitio

Public knowledge about dementia risk reduction in Norway

Background Several modifiable lifestyle risk factors for dementia have been identified, but it is unclear how much the Norwegian public knows about the relationship between lifestyle and brain health. Therefore, this study aimed to investigate knowledge about modifiable dementia risk and protective factors and beliefs and attitudes towards dementia and dementia risk reduction in a randomly selected subsample of the Norwegian population. Methods The total sample (n = 1435) included individuals aged 40–70 years from four counties (Oslo, Innlandet, Nordland and Trøndelag) in Norway. Two online questionnaires were used to measure (1) awareness about dementia risk reduction and (2) an individual`s motivation to change behaviour for dementia risk reduction (MOCHAD-10). Results Of the participants, 70% were aware of the potential of dementia risk reduction in general. Physical inactivity (86%), cognitive inactivity (84%) and social isolation (80%) were the most frequently recognised dementia risk factors. On the other hand, diabetes (26%), coronary heart disease (19%), hearing loss (18%) and chronic kidney disease (7%) were less often recognised as dementia risk factors. Comparing men and women, the only significant difference was that women were more likely to report parents with dementia as a risk factor compared to men. Gender, age and educational differences were seen in beliefs and attitudes towards dementia prevention:women reported more negative feelings and attitudes towards dementia than men;those aged 40–49 years – more likely than older age groups – reported that ‘knowing family members with dementia’ or ‘having risk factors’ made them believe they had to change their lifestyle and behaviour. Conclusions The results indicate that 70% of the Norwegian public are aware of the potential for dementia risk reduction in general. However, there are major gaps in existing knowledge, particularly for cardiovascular risk factors such as hypertension, coronary heart disease, hypercholesterolemia and metabolic factors (diabetes, obesity). These findings underline the importance of further informing the Norwegian public about lifestyle-related risk and protective factors of dementia. Differences in beliefs and attitudes towards dementia risk prevention by age, gender and education require tailored public risk reduction interventions

Additional file 1 of Public knowledge about dementia risk reduction in Norway

Additional file 1. Dementia awareness questionnaire

Additional file 3 of Public knowledge about dementia risk reduction in Norway

Additional file 3. Flowchart of the invited and participating sample

The brain structural and cognitive basis of odor identification deficits in mild cognitive impairment and Alzheimer's disease

Background: The objectives of this study were to explore the relationship between olfactory impairment, cognitive measures, and brain structure volumes in healthy elderly individuals, compared to patients with amnestic mild cognitive impairment (aMCI) or early Alzheimer’s disease (AD). The primary aim was to elucidate possible differences in cognitive scores and brain structure volumes between aMCI/AD patients with relatively intact odor identification (OI) ability and those with reduced ability. Methods: Twelve patients with aMCI, six with early AD, and 30 control subjects were included. OI abilities were assessed with the Brief Smell Identification Test (B-SIT) and Sniffin Sticks Identification Test (SSIT). Neuropsychological tests of executive functions and memory were performed. Brain structural volumes were obtained from T1 weighted 3D MRI at 3 Tesla. Statistical comparisons between the patients with aMCI and AD indicated no significant differences in performance on most tests. Since the groups were small and AD patients were in an early phase of disease, all patients were subsequently considered together as a single group for studying OI. Patients were subdivided into relatively intact (scores >50%) and reduced OI (≤ 50% score) on the olfactory tests. Results: The aMCI/AD group with reduced OI ability, as measured by both B-SIT and SSIT, had significantly smaller hippocampal volume as compared to the patient group with OI scores > 50%. There was a significant association between OI scores and hippocampal volume in the patient (not the control) group. Similar changes with tests of executive function and memory were not found. Low OI scores on B-SIT were associated with conversion from aMCI to AD in patients. The reduced OI patient group was significantly faster on Rey complex figure copying than the fairly intact OI group. Conclusion: The results from this pilot study suggest that the reduction in the size of hippocampus in connection with early AD is associated more with loss of OI ability rather than loss of memory, thus demonstrating that impaired OI is an early marker of medial temporal lobe degeneration

Additional file 2 of Public knowledge about dementia risk reduction in Norway

Additional file 2. Motivationto Change Lifestyle for Dementia Risk Reduction (MOHAD-10)