Age-related differences in cerebrovascular responses to cognitive stimulation using a novel method

Figures & data

Table 1. Demographics of the baseline, task-activated, and normotensive only datasets. Data are median [range], mean (standard deviation), or number (percentage). Significance testing by Chi-square (nominal data) or Mann–Whitney U (continuous data) between task-activated and normotensive only data-sets. Significant where p < 0.05

	Baseline data-set	Task-activated data-set	Normotensive only	P value
n	135	69	59
Age (years)	34.5 [19–83]	53 [21–83]	52 [21–83]	0.59
Female n (%)	69 (51)	40 (58)	39 (66)	0.44
Handedness n (%)
Right	126 (93)	63 (91)	53 (90)	0.78
Left	9 (7)	6 (8)	6 (10)
Total ACE-III score	-	98 [88–100]	98 [88–100]	0.92
Resting CBFv (cm/s) non-dominant	-	51.5 (9.9)	51.6 (9.8)	0.99
Resting CBFv (cm/s) dominant	-	52.0 (8.5)	51.8 (8.7)	0.88
BP (mmHg)	-	92.5 (13.6)	91.0 (13.5)	0.92

Table 2. Multiple linear regression of age and blood pressure (BP) on cerebral blood flow velocity (CBFv) in the non-dominant and dominant hemispheres. CI = confidence interval. Statistically significant where p < 0.05

	Adjusted R^2	Coefficient (95% CI)	F	P value
	CBFv (cm/s) non-dominant hemisphere
Age (years)	0.03	−0.13 (−0.26, 0.04)	3.65	0.58
BP (mmHg)		−0.05 (−0.14, 0.25)		0.59
	CBFv (cm/s) dominant hemisphere
Age (years)	0.02	−0.10 (−0.21, 0.02)	1.54	0.10
BP (mmHg)		0.11 (−0.06, 0.28)		0.20

Table 3. Correlation (Spearman) between cumulative response rate (CRR) and cognitive test score by age group. Cognitive test scores are Median [inter-quartile range]

Group	Cognitive tests score	Correlation	P value
	All
ACE-III total score	98 [96–99]	−0.12	0.33
Attention	18 [18–18]	0.16	0.19
Fluency	13 [12–14]	−0.16	0.19
Language	26 [26–26]	0.30	0.013
Visuospatial	16 [16–16]	0.11	0.39
Memory	26 [25–26]	−0.20	0.11
	Young (<40 years) (n = 26)
ACE-III total score	98 [97–100]	−0.21	0.31
Attention	18 [18–18]	−0.25	0.21
Fluency	13 [13–14]	0.03	0.88
Language	26 [26–26	−0.06	0.78
Visuospatial	16 [16–16]	0.15	0.45
Memory	26 [26–26]	−0.42	0.033
	Mid-life (40–59 years) (n = 18)
ACE-III total score	98 [95.5–100]	0.38	0.12
Attention	18 [18–18]	0.47	0.049
Fluency	14 [12–14]	−0.13	0.61
Language	26 [26–26]	0.63	0.005
Visuospatial	16 [16–16]	0.63	0.005
Memory	25 [24.5–26]	0.22	0.39
	Older (>59 years) (n = 25)
ACE-III total score	98 [95–98]	−0.15	0.47
Attention	18 [17–18]	−0.04	0.84
Fluency	13 [11–14]	−0.21	0.32
Language	26 [26–26]	0.26	0.22
Visuospatial	16 [15–16]	0.08	0.71
Memory	26 [25–26]	−0.25	0.22

Table 4. Median cumulative response rate (CRR) and [inter-quartile range] by age group. Significance testing across groups by Kruskal-Wallis

Age Group	CRR
Young (<40 years) (n=26)	6 [4.25-8]
Mid-life (40-59 years) (n=18)	9 [7.25-10]
Older (>59 years) (n=25)	8 [8-10]
P value	<0.005

Figure 1. Scatter diagram between age (years) with cumulative response rate (CRR), in the whole cohort (a), and normotensive group only (b). Line of best fit from linear regression

Figure 2. Representative traces of the CBFv response to the visuospatial task showing a response in an older adult (CCF = 0.97, VR = 22.94) (a), and absent response in a younger adult (CCF = 0.27, VR = 0.26) (b) as classified by the CCF₉₀ and VR₉₀ thresholds. The arrow denotes task initiation

Figure 3. Frequency distributions of number of responses by number of tasks in younger (a-black) and mid-life (b-gray), and older (c-dashed) adults. Categories 1–10 on the x-axis represent the cumulative number of responses out of ten tasks