JAMIE KNIGHT
Jamie Knight
PhD
Hello
Here's who I am & what I do
I'm a Post Doctoral Fellow in the Psychology Department at the University of Gothenburg, Sweden. I completed my PhD with Dr. Andrea Piccinin in Lifespan Development at the University of Victoria, in BC, Canada.
​
I'm interested in exploring how olfactory testing can detect the earliest signs of cognitive decline and dementia. My research focuses on neuropsychological and chemosensory functioning across the lifespan in the context of age-related cognitive decline and neurodegenerative diseases. Of particular interest to me, is how olfactory training can positively impact the brain.
Abstract
Background
The existing literature suggests that impaired olfaction may be an early marker for cognitive decline. Tracking the earliest stages of the progression to dementia is paramount, and yet the importance of olfactory ability throughout cognitive states and death remains unclear.
Methods
Drawing data from the Rush Memory and Aging Project (N = 1 501; 74% female), olfactory ability was assessed using the Brief Smell Identification Test (range = 0–16), while cognitive states (unimpaired, mild cognitive impairment [MCI], and dementia) were determined using a 3-step neuropsychological diagnostic protocol at up to 15 annual occasions. Multistate survival models simultaneously estimated the association of olfactory ability on transitions through cognitive states and death, while multinomial regression models estimated cognitively unimpaired and total life expectancies.
Results
Higher olfactory scores were associated with a reduced risk of transitioning from unimpaired cognition to MCI (hazard ratio [HR] = 0.86, 95% confidence interval [CI] = 0.82–0.88) and from MCI to dementia (HR = 0.89, 95% CI = 0.86–0.93), indicating that 1-unit increase in olfactory scores was associated with an approximate 14% and 11% reduction in risk, respectively. Additionally, higher olfactory scores were associated with a greater likelihood of transitioning backward from MCI to unimpaired cognition (HR = 1.07, 95% CI = 1.02–1.12). Furthermore, higher baseline olfactory scores were associated with more years of longevity without cognitive impairment. However, olfaction was not associated with the transition to death when accounting for transitions through cognitive states.
Conclusions
Findings suggest that higher olfactory identification scores are associated with a decreased risk of transitioning to impaired cognitive states and that associations between olfaction and mortality may occur primarily through the pathway of neurodegeneration.
Abstract
Objectives
To determine whether assessment-to-assessment fluctuations in episodic memory (EM) reflect fluctuations in olfaction over time.
Methods
Within-person coupled variation in EM and the Brief Smell Identification Test (BSIT) was examined in 565 participants aged 58–106 with autopsy data from the Rush Memory and Aging Project. A growth model for up to 15 years of EM data, with BSIT as time-varying covariate, was estimated accounting for main effects of sex, education, ε4 allele, and Alzheimer’s disease (AD) pathology, BSIT and time-varying BSIT, as well as the interaction between AD pathology and time-varying BSIT.
Results
Individuals with higher BSIT scores (b = .01, standard error [SE] = .004, p = .009) had slower declines in EM. High AD pathology (b = −.06, SE = .02, p = .001) was associated with more rapid declines in EM. The association between time-specific fluctuations in EM and BSIT differed by level of AD pathology (b = .08, SE = .034, p = .028), with a higher EM–BSIT association at higher levels of pathology.
Discussion
BSIT and EM fluctuate together over measurement occasions, particularly for individuals with AD pathology. Repeated intraindividual measurements provide information that could lead to early detection and inexpensive monitoring of accumulating AD pathology.