Odor Stick Identification Test for Japanese Patients with Olfactory Disturbances

Valid olfactory impairment tests can help identify mild cognitive impairment: an updated meta-analysis

Background

Olfactory testing is emerging as a potentially effective screening method for identifying mild cognitive impairment in the elderly population.

Objective

Olfactory impairment is comorbid with mild cognitive impairment (MCI) in older adults but is not well-documented in subdomains of either olfactory or subtypes of cognitive impairments in older adults. This meta-analysis was aimed at synthesizing the differentiated relationships with updated studies.

Methods

A systematic search was conducted in seven databases from their availability to April 2023. A total of 38 publications were included, including 3,828 MCI patients and 8,160 healthy older adults. Two investigators independently performed the literature review, quality assessment, and data extraction. The meta-analyses were conducted with Stata to estimate the average effects and causes of the heterogeneity.

Results

Compared to normal adults, MCI patients had severe impairments in olfactory function and severe deficits in specific domains of odor identification and discrimination. Olfactory impairment was more severe in patients with amnestic mild cognitive impairment than in patients with non-amnestic MCI. Diverse test instruments of olfactory function caused large heterogeneity in effect sizes.

Conclusion

Valid olfactory tests can be complementary tools for accurate screening of MCI in older adults.

Olfactory identification ability in patients with mild cognitive impairment and Alzheimer's disease

[Purpose] To examine the olfactory identification abilities and specify the difficult-to-identify odors in community-dwelling individuals with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). [Participants and Methods] We included, 12 and 17 patients with MCI (MCI group) and AD (AD group), respectively, and 30 community-dwelling older adults with no history of MCI or a dementia diagnosis (control group). Scores on the Japanese odor stick identification test (OSIT-J), an olfactory identification ability test, were compared among the three groups with intergroup differences examined accordingly. Next, we performed intergroup comparisons of the ratios of correct responses for each odor, and the difficult-to-identify odors were examined. [Results] OSIT-J scores of the MCI and AD groups were significantly lower than those of the control group. There were no intergroup differences in the correct identification of pungent odors. No patients in the AD group could identify the odor of cooking gas. The ability to identify food-related odors was reduced in the MCI and AD groups. [Conclusion] Patients with MCI and AD had reduced olfactory identification abilities in comparison to community-dwelling older adults without cognitive decline. These findings suggest the importance of olfactory evaluation before providing patients with dementia with therapeutic interventions associated with olfactory stimuli.

Minor hallucinations in isolated rapid eye movement sleep behavior disorder indicative of early phenoconversion: A preliminary study

OBJECTIVES

Minor hallucinations (MH) are psychotic symptoms that can occur anywhere between prodromal to early Parkinson's disease and after onset of motor problems. MH include visual illusions, presence hallucinations, and passage hallucinations. Isolated rapid eye movement sleep behavior disorder (RBD) is a harbinger of neurodegenerative diseases. We conducted a retrospective cohort study to investigate the clinical characteristics of isolated RBD with MH and the risk of phenoconversion.

MATERIALS AND METHODS

We retrospectively analyzed the data of 36 patients with isolated RBD (four females; median age, 75.0 years). We defined cases reporting at least one minor hallucination as RBD with MH. Demographic data and cognitive function were compared between patients with and without MH, and Cox proportional hazards models estimated the risk of phenoconversion.

RESULTS

We included 10 (27.8%) patients with MH and 26 (72.2%) without MH. Patients with MH were older, had less dopamine transporter accumulation, more severe autonomic dysfunction, more depressive symptoms, and lower verbal fluency and symbol coding test scores than patients without MH. After follow-up (median, 2.50 years), 13.9% (5/36) of all patients developed phenoconversion (Parkinson's disease, two patients; dementia with Lewy bodies, three patients). The rate of phenoconversion was significantly higher in patients with MH (40.0% vs. 3.8%, p = .005). The Cox proportional hazards model adjusted for age, sex, and disease duration revealed that MH was a significant risk factor for phenoconversion (hazard ratio, 14.72; 95% confidence interval, 1.35-160.5).

CONCLUSIONS

Minor hallucinations may be utilized as early clinical markers for prodromal estimation of neurodegenerative diseases.

Efficacy of Olfactory and Pareidolia Tests Compared With That of Indicative Biomarkers in Diagnosis of Dementia With Lewy Bodies

Purpose: Although olfactory decline and visual hallucinations are useful in distinguishing dementia with Lewy bodies (DLB) from Alzheimer's disease (AD) in a clinical setting, neither is easy to evaluate objectively. The pareidolia test is used to assess susceptibility to visual hallucinations, while in Japan, the Odor Stick Identification Test for the Japanese (OSIT-J) is used to objectively quantify olfactory decline. The present study investigated the efficacy of these olfactory and pareidolia tests in differentiating AD from DLB. Their usefulness was then compared with that of the indicative biomarkers in neuroimaging for a clinical diagnosis of DLB listed in the Fourth Consensus Report of the Dementia with Lewy Bodies Consortium.

Methods: A total of 24 probable DLB and 22 probable AD patients were enrolled. All underwent 4 diagnostic procedures: uptake of dopamine transporter in single photon emission computed tomography (DaT-SPECT) and meta-iodobenzylguanidine (MIBG) in myocardial scintigraphy, the pareidolia test, and OSIT-J. The sensitivity, specificity, and accuracy of these methods in differentiating DLB from AD were compared.

Results: Sensitivity and specificity in differentiating DLB from AD were 86 and 100% by the heart-to-mediastinum ratio of MIBG uptake; 82 and 96% by the specific binding ratio on DaT-SPECT; 77 and 67% by the combination of OSIT-J and pareidolia test scores; 73 and 62% by the pareidolia test scores; and 77 and 58% by the OSIT-J scores, respectively.

Conclusions: The present results suggest that the pareidolia and OSIT-J tests may be considered before resorting to nuclear neuroimaging in the diagnosis of DLB.

Olfactory function in elderly people and patients with Alzheimer's disease

BACKGROUND

Olfactory function is an important sensory perception function that helps us detect the smell of spoiled food, dirty clothing, and gas leaks. If ageing and Alzheimer's disease (AD) are accompanied by a decline in olfactory function, this might reduce the ability to sense danger, placing the safety and hygiene of elderly people at risk.

METHODS

Subjects in this study included 113 healthy subjects aged 20-89 years and 12 persons with AD aged 62-85 years. The healthy subjects were divided into three groups according to age: young-adult group (20-43 years), middle-adult group (45-69 years), and old-adult group (70-89 years). The Hasegawa Dementia Scale-Revised score of AD subjects ranged from 15 to 26. We developed and implemented an odour identification ability test and a situational judgement test using an odour stick to examine the impact of ageing and AD on olfactory function from the perspective of sensing danger. To examine the impact of mild AD on the olfactory function, we compared the scores between the AD group and the age-matched control group.

RESULTS

The scores for the situational judgement and odour identification ability tests were significantly lower in an old-adult group than in the young-adult and middle-adult groups. A significant correlation was found between age and scores for both tests in the control group. The AD group exhibited significantly lower total scores on both tests compared with the age-matched controls.

CONCLUSIONS

These results suggest that ageing and mild AD may reduce the ability to identify odours and judge situations based on odours.

[Olfactory disturbance screening with the odor stick identification test (OSIT-J) in executive checkups]

The odor stick identification test for Japanese (OSIT-J) has been shown to be useful for detecting and evaluating olfactory disturbances in Japanese people. We studied the usefulness of OSIT-J in screening for olfactory disturbances in 83 Japanese participants (49 male, 34 female) participating in an executive checkup at NTT West Kanazawa Hospital in Japan. The olfactory ability was self-reported on a grade scale. Olfactory function was then evaluated with a three-odors OSIT-J (rose, curry and sweaty socks). Participants with low self-reported olfactory ability or less-than-full scores in the three-odor test were evaluated with an additional 10 odors of OSIT-J. Eight or less points are considered to be lower than average in the 13-odor test of OSIT-J (Saito S, et al.). Eleven of the 83 participants had low self-reported olfactory ability. Four participants with a full score in the three odors test with low self-reported olfactory ability scored more than eight points in the 13-odor test. Thirty-eight participants scored less than three points in the three-odor test. Seven of 29 participants with two points in the three-odor test scored eight or less in the 13-odor test. In the 29 participants, subjects with low self-reported olfactory ability scored significantly lower scores than those without a low self-reported olfactory ability in the 13-odor test. The self-reported olfactory ability was not related to the score in the 13-odor test in the nine participants with one point or less in the three-odor test. Males scored significantly lower scores than females in the three-odor test. However, gender was not significantly related to the rate of olfactory disability estimated based on the 13-odor test. Use of a three-odor OSIT-J along with a self-administered questionnaire pertaining to olfactory disability is useful for olfactory disturbance screening during executive health checkups.