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

Abstract

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.

A Systematic Review of the Definitions of Vascular Cognitive Impairment, No Dementia in Cohort Studies

“…When assessing global cognitive function, the MoCA may be more useful than the MMSE for detecting cognitive impairment particularly in early stages of VCI [42]. Previous research has suggested that fluid abilities (e.g., information processing speed) may be more vulnerable to cerebrovascular dysfunction than crystallised abilities, at least at non-severe impairment stages [7,43]. Therefore, VCI-ND prevalence rates may be higher if the definition of VCI-ND includes impairment of fluid abilities.…”

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

“…Whilst the paradigms are the same and the current sample speaks English rather than German in the earlier work, the major difference between the populations is the age: between 17 and 50 in Knecht et al,average of 26; versus between 60 and 85, average of 69 in the current study. This may be the critical factor as language lateralisation is reported to reduce with aging (Keage et al, 2015;Matteis et al, 1998). The is consistent with increased rates of non- The work adds to the methods available for assessing lateralisation using fTCD in children, including Picture Naming (Haag et al, 2010;Lohmann et al, 2005), Story Listening (Stroobant et al, 2011), and Animation Description (Bishop et al, 2009 We employed two novel approaches to data exploration and retention using DOPOSCCI (Badcock, Holt, et al, 2012).…”

“…Blood flow velocity was measured using a Doppler ultrasonography device (Doppler-Box™, DWL Elektronische Systeme, Singen, Germany) with a Diamon® headset or elastic headbands to hold 2-MHz transducer probes over the left and right temporal skull windows to insonate the middle cerebral arteries. Seated participants viewed the Psychtoolbox (Brainard, 1997;Pelli, 1997 Keage et al, 2015;Kohler et al, 2015).…”

“…The Word Generation data were processed as described above with timings based on previous research (Keage et al, 2015;Knecht et al, 1996;; epoch -15 to 25 secs, baseline -15 to -5, and period of interest 5 to 15. Individually calculated cut-offs were used for activation separation epoch exclusion, five times the inter-quartile range (for reference, the average median activation separation was 3.80, IQR = 2.89, Min = 1.16, Max = 13.06).…”

“…Given the flexibility of the task, it will be useful in populations with atypical development such as dyslexia, specific language impairment, and Autism; where research has previously used the Word Generation in adults (dyslexia, Illingworth & Bishop, 2009; specific language impairment and autism, Whitehouse & Bishop, 2008). In addition, the simplicity of What Box makes it useful for working with populations where memory for and adherence to the rules associated with Word Generation limit its application; including, intellectual impairment (e.g., Down syndrome, Bowler, Cufflin, & Kiernan, 1985), What box language lateralisation 25 cognitive decline such as aging (Keage et al, 2015), dementia (Matteis et al, 1998), and brain damage (Bragoni et al, 2000). TCD per se has been applied successfully in a wide range of populations (for systematic reviews see Bakker et al, 2014in children, Keage et al, 2012 in aging and dementia), therefore the combination of fTCD and What Box provides a useful tool.…”