Louise Lavrencic


Factors Associated with the High Prevalence of Dementia in Older Aboriginal Australians.

Radford K, Lavrencic LM, Delbaere K, Draper B, Cumming R, Daylight G, Mack HA, Chalkley S, Bennett H, Garvey G, Hill TY, Lasschuit D, Broe GA

Is There a Link Between Cognitive Reserve and Cognitive Function in the Oldest-Old?

Lavrencic LM, Richardson C, Harrison SL, Muniz-Terrera G, Keage HAD, Brittain K, Kirkwood TBL, Jagger C, Robinson L, Stephan BCM

In the oldest-old, higher reserve associated with better baseline global and domain-specific cognitive function and reduced risk of prevalent dementia; but not cognitive decline or incident dementia. Increasing reserve could promote cognitive function in the oldest-old. The results suggest there would be little impact on trajectories, but replication is needed. Development of preventative strategies would benefit from identifying the role of each factor in building reserve and why rate of change is not affected.

Cognitive reserve is not associated with improved performance in all cognitive domains.

Lavrencic LM, Churches OF, Keage HAD

Cognitive reserve beneficially affects cognitive performance, even into advanced age. However, the benefits afforded by high cognitive reserve may not extend to all cognitive domains. This study investigated whether cognitive reserve differentially affects performance on cognitive tasks, in 521 cognitively healthy individuals aged 60 to 98 years (Mage = 68, SD = 6.22, 287 female); years of education was used to index cognitive reserve. Cognitive performance variables assessed attention, executive functions, verbal memory, motor performance, orientation, perception of emotion, processing speed, and working memory. Bootstrapped regression analyses revealed that cognitive reserve was associated with attention, executive functions, verbal and working memory, and orientation; and not significantly related to emotion perception, processing speed, or motor performance. Cognitive reserve appears to differentially affect individual cognitive domains, which extends current theory that purports benefits for all domains. This finding highlights the possibility of using tests not (or minimally) associated with cognitive reserve, to screen for cognitive impairment and dementia in late life; these tests will likely best track brain health, free of compensatory neural mechanisms.

What Box: A task for assessing language lateralization in young children.

Badcock NA, Spooner R, Hofmann J, Flitton A, Elliott S, Kurylowicz L, Lavrencic LM, Payne HM, Holt GK, Holden A, Churches OF, Kohler MJ, Keage HAD

The assessment of active language lateralization in infants and toddlers is challenging. It requires an imaging tool that is unintimidating, quick to setup, and robust to movement, in addition to an engaging and cognitively simple language processing task. Functional Transcranial Doppler Ultrasound (fTCD) offers a suitable technique and here we report on a suitable method to elicit active language production in young children. The 34-second "What Box" trial presents an animated face "searching" for an object. The face "finds" a box that opens to reveal a to-be-labelled object. In a sample of 95 children (1 to 5 years of age), 81% completed the task-32% with ≥10 trials. The task was validated (ρ = 0.4) against the gold standard Word Generation task in a group of older adults (n = 65, 60-85 years of age), though was less likely to categorize lateralization as left or right, indicative of greater measurement variability. Existing methods for active language production have been used with 2-year-old children while passive listening has been conducted with sleeping 6-month-olds. This is the first active method to be successfully employed with infants through to pre-schoolers, forming a useful tool for populations in which complex instructions are problematic.

Social cognition is not associated with cognitive reserve in older adults.

Lavrencic LM, Kurylowicz L, Valenzuela MJ, Churches OF, Keage HA

Social and general cognitive abilities decline in late life. Those with high cognitive reserve display better general cognitive performance in old age; however, it is unknown whether this is also the case for social cognition. A total of 115 healthy older adults, aged 60-85 years (m = 44, f = 71) were assessed using The Awareness of Social Inference Test (TASIT-R; social cognition), the Lifetime of Experiences Questionnaire (LEQ; cognitive reserve), and the Wechsler Abbreviated Scale of Intelligence (WASI-II; general cognitive ability). The LEQ did not predict performance on any TASIT-R subtest: Emotion Evaluation Test (β = -.097, p = .325), Social Inference – Minimal (β = -.004, p = .972), or Social Inference – Enriched (β = -.016, p = .878). Sensitivity analyses using two alternative cognitive reserve measures, years of education and the National Adult Reading Test, supported these effects. Cognitive reserve was strongly related to WASI-II performance. Unlike general cognitive ability, social cognition appears unaffected by cognitive reserve. Findings contribute to the emerging understanding that cognitive reserve differentially affects individual cognitive domains, which has implications for the theoretical understanding of cognitive reserve and its brain correlates. Cognitive measures unbiased by cognitive reserve may serve as best indicators of brain health, free of compensatory mechanisms.

Cerebrovascular function associated with fluid, not crystallized, abilities in older adults: A transcranial Doppler study.

Keage HA, Kurylowicz L, Lavrencic LM, Churches OF, Flitton A, Hofmann J, Kohler M, Badcock NA

The brain is dependent on the cerebrovascular system, particularly microvasculature, for a consistent blood supply; however, age-related changes in this system affect neuronal and therefore cognitive function. Structural vascular markers and vascular disease appear to preferentially affect fluid cognitive abilities, sparing crystallized abilities. We sought to investigate the relationships between cerebrovascular function and cognitive domains. Fifty individuals between 60 and 75 years of age (31 women, 19 men) underwent cognitive testing: Wechsler Vocabulary and Matrix Reasoning subtests (crystallized and fluid ability measures, respectively Wechsler, 2011), and the Addenbrooke's Cognitive Examination-Revised (ACE-R; general cognitive ability; Mioshi, Dawson, Mitchell, Arnold, & Hodges, 2006). Transcranial Doppler (TCD) measures were also collected at rest and during a cognitive word-generation task, from which a lateralization index was calculated. Lower pulsatility index at rest, and greater left lateralization during the TCD cognitive task were associated with better performance on the Matrix Reasoning but not the Vocabulary test; these effects were independent from each other and from any vascular comorbidity burden. These functional findings confirm previous structural studies, which revealed that fluid abilities are more vulnerable to cerebrovascular dysfunction than crystallized abilities, and identify two (likely related) mechanisms: degraded cerebrovascular integrity (indexed by pulsatility index) and a delateralization of function. Cerebrovascular dysfunction is a key contributor to cognitive aging that deserves further attention, particularly in relation to early diagnostic markers of impairment and monitoring of vascular (e.g., physical activity) interventions.