Olfactory Identification in Subjective Cognitive Decline: A Meta-Analysis

2021 ◽  
Vol 79 (4) ◽  
pp. 1497-1507
Author(s):  
Benoît Jobin ◽  
Rayane Zahal ◽  
Eve-Line Bussières ◽  
Johannes Frasnelli ◽  
Benjamin Boller
Keyword(s):  
Cognitive Impairment ◽  
Cognitive Decline ◽  
Meta Analysis ◽  
Subjective Cognitive Decline ◽  
Control Group ◽  
Subjective Memory ◽  
Healthy Older Adults ◽  
Early Marker ◽  
Olfactory Identification ◽  
Memory Concerns

Background: Recently, subjective cognitive decline (SCD) has been considered to be one of the first signs of Alzheimer’s disease (AD). Since this potential early marker is sensitive but not specific to AD, combining it with other markers could ensure higher accuracy when predicting which persons with SCD will convert to AD. Since olfactory dysfunction is observable in both AD and mild cognitive impairment (MCI), it is a promising marker that could help improve the early diagnosis of AD. Objective: The aim of this meta-analysis was to verify whether the presence of SCD is associated with a decrease in olfactory identification ability. Methods: We collected articles from the following databases: PsychNet, PubMed, Ebsco, and ProQuest using the keywords: “SCD”, “subjective cognitive decline”, “subjective cognitive impairment”, “subjective memory impairment”, “subjective memory decline”, “cognitive complaints”, “memory complaints”, “cognitive concerns”, “memory concerns”, “olfac*” and “smell”. We included articles according to the following criteria: 1) participants aged 50 and over; 2) presence of an SCD group or a conceptual equivalent; 3) presence of a healthy control group with the same age range; and 4) assessment of olfactory identification ability. Results: Five studies met the inclusion criteria. Small and homogeneous effects were observed for olfactory identification alteration in individuals with SCD relative to controls (g = –0.16, 95% CI [–0.46, 0.14]). Conclusion: Despite the low number of studies included, the findings suggest that odor identification is slightly altered in SCD compared to healthy older adults. This alteration in individuals with SCD could be an early marker of AD.

scholarly journals Subjective cognitive decline: The first clinical manifestation of Alzheimer's disease?

2016 ◽  
Vol 10 (3) ◽  
pp. 170-177 ◽  
Author(s):  
Adalberto Studart Neto ◽  
Ricardo Nitrini
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Clinical Manifestation ◽  
Neurodegenerative Disorder ◽  
Subjective Cognitive Decline ◽  
Subjective Memory ◽  
Increased Risk

ABSTRACT Background: Mild cognitive impairment is considered as the first clinical manifestation of Alzheimer's disease (AD), when the individual exhibits below performance on standardized neuropsychological tests. However, some subjects before having a lower performance on cognitive assessments already have a subjective memory complaint. Objective: A review about subjective cognitive decline, the association with AD biomarkers and risk of conversion to dementia. Methods: We performed a comprehensive non-systematic review on PubMed. The keywords used in the search were terms related to subjective cognitive decline. Results: Subjective cognitive decline is characterized by self-experience of deterioration in cognitive performance not detected objectively through formal neuropsychological testing. However, various terms and definitions have been used in the literature and the lack of a widely accepted concept hampers comparison of studies. Epidemiological data have shown that individuals with subjective cognitive decline are at increased risk of progression to AD dementia. In addition, there is evidence that this group has a higher prevalence of positive biomarkers for amyloidosis and neurodegeneration. However, Alzheimer's disease is not the only cause of subjective cognitive decline and various other conditions can be associated with subjective memory complaints, such as psychiatric disorders or normal aging. The features suggestive of a neurodegenerative disorder are: onset of decline within the last five years, age at onset above 60 years, associated concerns about decline and confirmation by an informant. Conclusion: These findings support the idea that subjective cognitive complaints may be an early clinical marker that precedes mild cognitive impairment due to Alzheimer's disease.

Subjective Memory Complaints and Conversion to Dementia in Patients with Subjective Cognitive Decline and Patients with Mild Cognitive Impairment

2016 ◽  
Vol 27 (2) ◽  
pp. 85-93 ◽  
Author(s):  
Johann Lehrner ◽  
Bettina Bodendorfer ◽  
Claus Lamm ◽  
Doris Moser ◽  
Peter Dal-Bianco ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Verbal Memory ◽  
Clinical Sample ◽  
Subjective Cognitive Decline ◽  
Memory Testing ◽  
Cognitive Complaints ◽  
Subjective Memory ◽  
Subjective Cognitive Complaints

Abstract. Background: Subjective cognitive complaints and their clinical significance are discussed controversially. Objectives: To determine the clinical validity of subjective cognitive complaints among subjects with subjective cognitive decline (SCD) and mild cognitive impairment (MCI). Design: Longitudinal study with one follow up examination at a University based out-patient memory clinic. Participants: A clinical sample of patietns with SCD and MCI (n = 141), aged 50 and older, who came to the memory outpatient clinic. Results: No significant differences between converters and non converters regarding subjective cognitive complaints were detected. MCI patients had a higher risk than the patients with SCD developing AD (OR = 7.3 [CI 0.9 to 61.2]. Verbal memory testing using the Verbal Selektive Reminding Test (VSRT) showed better diagnostic validity than subjective cognitive complaints using the Forgetfulness Assessment Inventory (FAI) in predicting conversion to dementia. Conclusion: Verbal memory testing was superior in predicting conversion to dementia compared to subjective cognitive complaints.

scholarly journals Effect of Tai Chi on Cognitive Function among Older Adults with Cognitive Impairment: A Systematic Review and Meta-Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Renjun Gu ◽  
Yujia Gao ◽  
Chunbing Zhang ◽  
Xiaojuan Liu ◽  
Zhiguang Sun
Keyword(s):  
Systematic Review ◽  
Older Adults ◽  
Cognitive Impairment ◽  
Cognitive Function ◽  
Cognitive Decline ◽  
Tai Chi ◽  
Digit Span ◽  
Meta Analysis ◽  
Control Group ◽  
Clinical Dementia Rating

Background. Cognitive decline occurs in all persons during the aging process and drugs can only alleviate symptoms and are expensive. Some researches demonstrated that Tai Chi had potential in preventing cognitive decline while others’ results showed Tai Chi had no influence on cognitive impairment. Therefore, we conduct a systematic review and meta-analysis to assess the efficacy and safety of cognitive impairment patients practicing Tai Chi. Methods. A comprehensive literature search was carried out in multiple databases, including PubMed, Cochrane, MEDLINE (Ovid), Web of Science, Embase, Scopus, PsycInfo (Ovid), CKNI, Wan Fang, VIP, SinoMed, and ClinicalTrails, from their inception to 1 July 2020 to collect randomized controlled trials about practicing Tai Chi for patients with cognitive impairment. Primary outcomes included changes of cognitive function and secondary outcomes included changes of memory functions. Data were extracted by two independent individuals and Cochrane Risk of Bias tool version 2.0 was applied for the included studies. Systematic review and meta-analysis were performed by RevMan 5.3 software. Results. The results included 827 cases in 9 studies, of which 375 were in the experimental group and 452 were in the control group. Meta-analysis showed that Mini-Mental State Examination WMD = 1.52, 95% CI [0.90, 2.14]; Montreal Cognitive Assessment WMD = 3.5, 95% CI [0.76, 6.24]; Clinical Dementia Rating WMD = −0.55, 95% CI [−0.80, −0.29]; logical memory delayed recall WMD = 1.1, 95% CI [0.04, 2.16]; digit span forward WMD = 0.53, 95% CI [−0.65, 1.71]; and digit span backward WMD = −0.1, 95% CI [−0.38, 0.19]. No adverse events were reported in the included articles. Conclusion. There is limited evidence to support that practicing Tai Chi is effective for older adults with cognitive impairment. Tai Chi seems to be a safe exercise, which can bring better changes in cognitive function score.

Association of Subjective Cognitive Decline with Risk of Cognitive Impairment and Dementia: A Systematic Review and Meta-Analysis of Prospective Longitudinal Studies

2021 ◽  
pp. 1-9
Author(s):  
X.-T. Wang ◽  
Z.-T. Wang ◽  
H.-Y. Hu ◽  
Y. Qu ◽  
M. Wang ◽  
...  
Keyword(s):  
Systematic Review ◽  
Cognitive Impairment ◽  
Cognitive Decline ◽  
Meta Analysis ◽  
Cognitive Disorders ◽  
Excess Risk ◽  
Subjective Cognitive Decline ◽  
Healthy Individuals ◽  
Subgroup Analyses ◽  
Fold Excess

Background: Subjective cognitive decline (SCD) as an early pathological manifestation of brain aging has become more prevalent among older adults. Objectives: We aimed to investigate the associations of subjective cognitive decline (SCD) with the combined risk of cognitive impairment and dementia. Design: We performed a systematic review and meta-analysis via searching Embase, PubMed and Cochrane electronic databases from January 1 st 1970 to June 4th, 2020. Setting: Prospective cohort studies Participants: Healthy individuals were recruited from community, clinics and population. Measurements: Healthy individuals with SCD were classified into exposure groups, while those without were considered as the reference group. Adjusted relative risks (RR) were estimated in a random-effects model. Both primary and subgroup analyses were conducted. Results: Of 28,895 identified studies, 21 studies containing 22 cohorts were eligible for inclusion in the meta-analysis. SCD increased the risk of subsequent cognitive disorders (RR=2.12, 95% confidence intervals [CI] =1.75-2.58, I2=87%, P<0.01). To be specific, SCD conferred a 2.29-fold excess risk for cognitive impairment (RR=2.29, 95% CI=1.66-3.17, I2=83%, P<0.01) and a 2.16-fold excess risk for dementia (RR=2.16, 95% CI=1.63-2.86, I2=81%, P<0.01). In subgroup analyses, participants with SCD in the subgroup of 65-75 years old, long-education (>15 years) subgroup and subgroup of clinics showed a higher risk of developing objective cognitive disorders. Conclusions: SCD is associated with an increased combined risk of cognitive impairment and incident dementia and should be considered a risk factor for objective cognitive disorders.

scholarly journals Subjective cognitive decline: opposite links to neurodegeneration across the Alzheimer’s continuum

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Elizabeth Kuhn ◽  
Audrey Perrotin ◽  
Clémence Tomadesso ◽  
Claire André ◽  
Siya Sherif ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Subjective Cognitive Decline ◽  
Maladie D’Alzheimer ◽  
Subjective Memory ◽  
Memory Decline ◽  
Memory Awareness

Abstract Subjective memory decline is associated with neurodegeneration and increased risk of cognitive decline in participants with no or subjective cognitive impairment, while in patients with mild cognitive impairment or Alzheimer’s-type dementia, findings are inconsistent. Our aim was to provide a comprehensive overview of subjective memory decline changes, relative to objective memory performances, and of their relationships with neurodegeneration, across the clinical continuum of Alzheimer’s disease. Two hundred participants from the Imagerie Multimodale de la maladie d'Alzheimer à un stade Précoce (IMAP+) primary cohort and 731 participants from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) replication cohort were included. They were divided into four clinical groups (Imagerie Multimodale de la maladie d'Alzheimer à un stade Précoce/Alzheimer’s Disease Neuroimaging Initiative): controls (n = 67/147, age: 60–84/60–90, female: 54/55%), patients with subjective cognitive decline (n = 30/84, age: 54–84/65–80, female: 44/63%), mild cognitive impairment (n = 50/369, age: 58–86/55–88, female: 45/44%) or Alzheimer’s-type dementia (n = 36/121, age: 51–86/61–90, female: 41/41%). Subjective and objective memory scores, and their difference (i.e. delta score reflecting memory awareness), were compared between groups. Then, voxelwise relationships between subjective memory decline and neuroimaging measures of neurodegeneration [atrophy (T1-MRI) and hypometabolism (18F-fluorodeoxyglucose-PET)] were assessed across clinical groups and the interactive effect of the level of cognitive impairment within the entire sample was assessed. Analyses were adjusted for age, sex and education, and repeated including only the amyloid-positive participants. In Imagerie Multimodale de la maladie d'Alzheimer à un stade Précoce, the level of subjective memory decline was higher in all patient groups (all P &lt; 0.001) relative to controls, but similar between patient groups. In contrast, objective memory deficits progressively worsened from the subjective cognitive decline to the dementia group (all P &lt; 0.001). Accordingly, the delta score showed a progressive decline in memory awareness across clinical groups (all P &lt; 0.001). Voxelwise analyses revealed opposite relationships between the subjective memory decline score and neurodegeneration across the clinical continuum. In the earliest stages (i.e. patients with subjective cognitive decline or Mini Mental State Examination &gt; 28), greater subjective memory decline was associated with increased neurodegeneration, while in later stages (i.e. patients with mild cognitive impairment, dementia or Mini Mental State Examination &lt; 27) a lower score was related to more neurodegeneration. Similar findings were recovered in the Alzheimer’s Disease Neuroimaging Initiative replication cohort, with slight differences according to the clinical group, and in the amyloid-positive subsamples. Altogether, our findings suggest that the subjective memory decline score should be interpreted differently from normal cognition to dementia. Higher scores might reflect greater neurodegeneration in earliest stages, while in more advanced stages lower scores might reflect decreased memory awareness, i.e. more anosognosia associated with advanced neurodegeneration.

scholarly journals P4-246: ASSESSMENT OF SUBJECTIVE MEMORY ABILITY IN MILD COGNITIVE IMPAIRMENT AND SUBJECTIVE COGNITIVE DECLINE

2019 ◽  
Vol 15 ◽  
pp. P1372-P1373
Author(s):  
Linda Mah ◽  
Frankie Chan ◽  
Aliya Ali ◽  
Mirjam Mulder-Heijstra ◽  
Susan Vandermorris ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Subjective Cognitive Decline ◽  
Subjective Memory ◽  
Memory Ability

Identification of odors, faces, cities and naming of objects in patients with subjective cognitive decline, mild cognitive impairment and Alzheimer´s disease: a longitudinal study

2018 ◽  
Vol 31 (04) ◽  
pp. 537-549 ◽  
Author(s):  
R. Tahmasebi ◽  
S. Zehetmayer ◽  
G. Pusswald ◽  
G. Kovacs ◽  
E. Stögmann ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Semantic Memory ◽  
Predictive Accuracy ◽  
Olfactory Dysfunction ◽  
Subjective Cognitive Decline ◽  
Amnestic Mci ◽  
Olfactory Identification

ABSTRACTObjective:Recent studies have tried to find a reliable way of predicting the development of Alzheimer´s Disease (AD) among patients with mild cognitive impairment (MCI), often focusing on olfactory dysfunction or semantic memory. Our study aimed to validate these findings while also comparing the predictive accuracy of olfactory and semantic assessments for this purpose.Method:Six hundred fifty patients (median age 68, 58% females) including controls, SCD (subjective cognitive decline), non-amnestic MCI (naMCI), amnestic MCI (aMCI), and AD patients were tested for olfactory dysfunction by means of odor identification testing and semantic memory. Of those 650 patients, 120 participants with SCD, naMCI, or aMCI at baseline underwent a follow-up examination after two years on average. Of these 120 patients, 12% had developed AD at follow-up (converters), while 88% did not develop AD at follow-up (non-converters).Results:Analysis showed a significant difference only for initial olfactory identification between converters and non-converters. Sensitivity of impairment of olfactory identification for AD prediction was low at 46.2%, although specificity was high at 81.9%. Semantic memory impairment at baseline was not significantly related to AD conversion, although, when naming objects, significant differences were found between AD patients and all other groups and between naMCI and aMCI patients compared to controls and SCD patients.Conclusions:Objective olfactory assessments are promising instruments for predicting the conversion to AD among MCI patients. However, due to their low sensitivity and high specificity, a combination with other neuropsychological tests might lead to an improved predictive accuracy. Further longitudinal studies with more participants are required to investigate the usefulness of semantic memory tests in this case.

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