Clinical, genotypic and olfactory characteristics of patients with 11C ⁃ PIB ⁃ positive cognitive impairment

Abstract

Background To summarize the clinical, genotype and olfactory characteristic in patients with 11 C⁃Pittsburgh compound B (11C⁃PIB)⁃positive cognitive impairment. Methods Twenty⁃seven patients with 11C ⁃ PIB ⁃ positive cognitive impairment, including 19 patients with Alzheimer's disease (AD) and 8 patients with mild cognitive impairment (MCI), were recruited from January 2015 to February 2016 in Tianjin Huanhu Hospital. The clinical, genotype and olfactory profiles were retrospectively analyzed. Mini ⁃ Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA) and Clock Drawing Test (CDT), Neuropsychiatric Inventory (NPI), Activity of Daily Living Scale (ADL), and Hamilton Depression Scale ⁃ 21 (HAMD ⁃ 21) were used to evaluate cognitive function, behavioral and psychological symptoms, activities of daily living, and symptoms of depression, respectively. Polymerase chain reaction ⁃ restriction fragment length polymorphism (PCR ⁃ RFLP) was used to determine ApoE genotype, and T ＆ T olfactometer was used to test threshold of detection and recognition. Results Compared with MCI patients, AD patients had lower MMSE score (P = 0.000), orientation to time (P = 0.031), short ⁃ term memory (P = 0.021), recall (P = 0.009), calculation (p = 0.000), repetition (P = 0.038), reading (P = 0.021), writing (P = 0.002), visual ⁃ spatial ability (P = 0.039), MoCA score (P = 0.000) and CDT score (P = 0.020), and higher ADL score (P = 0.000). But there was no significant difference in orientation to place, naming, comprehension, NPI score and HAMD⁃21 score between 2 groups (P > 0.05, for all). There were no statistical differences in incidence of olfactory dysfunction, threshold of detection and recognition between 2 groups (P > 0.05, for all). There were statistical differences in the incidence of olfactory disorders among different ApoE genotypes  Fisher's exact probability : P = 0.000). To further evaluate the effect of ApoE ε 4 allele on the olfactory function, subjects were additionally dichotomized according to the presence or absence of at least one ApoEε4 allele. Comparing with the subjects without ApoE ε 4 allele, the olfactory function decreased significantly in those with ApoE ε 4 allele (0/11 vs. 12/13; Fisher's exact probability : P = 0.000). Conclusions The patients with 11 C⁃PIB ⁃ positive cognitive impairment (AD and MCI) had significant olfactory  isturbance, which was related to ApoE ε 4 allele. The assessment of clinical, genotype and olfactory characteristic was helpful in early diagnosis of AD patients.DOI：10.3969/j.issn.1672⁃6731.2020.05.013