Figures
- FIGURE 1
Flow diagram describing the study protocol. MMSE: mini mental state examination; RTI: respiratory tract infection; DLB: dementia with Lewy bodies; AD: Alzheimer's disease; UTC: urge-to-cough.
- FIGURE 2
Relationship between cognitive function and the cough reflex sensitivity, showing significant differences between a) the relationship between mini mental state examination (MMSE) score and log C2 (where C2=lowest concentration of inhaled citric acid that could induce ≥2 coughs) and b) the relationship between MMSE and log C5 (where C5=lowest concentration of inhaled citric acid that could induce ≥5 coughs).
- FIGURE 3
Comparison of cough reflex sensitivity among the control group, the Alzheimer's disease (AD) group and the dementia with Lewy bodies (DLB) group, showing: (a) the relationship of log C2 (where C2=lowest concentration of inhaled citric acid that could induce ≥2 coughs) for each group; (b) the relationship of log C5 (where C5=lowest concentration of inhaled citric acid that could induce ≥5 coughs) with each group. Two-way ANOVA showed significant differences in log C2 and log C5 between the DLB group and the control group or the AD group (p1=0.002 (a) and p1=0.0004 (b), as adjusted for gender). Post hoc tests showed significant differences in log C2 and log C5 between the DLB group and the control group or the AD group (p=0.003 and p=0.045, respectively (a) and p=0.001 and p=0.016, respectively (b), as adjusted for gender)
- FIGURE 4
Relationship between cognitive function and the urge-to-cough (UTC), showing: a) the relationship between mini mental state examination (MMSE) score and log Cu (where Cu=concentration of citric acid at a threshold of UTC), which illustrates significant differences; b) a comparison of log Cu between the control group, the Alzheimer's disease (AD) group and the dementia with Lewy bodies (DLB) group. Log Cu in the DLB group was significantly higher than in the control group and the AD group (p1=0.004, as adjusted for gender). Post hoc tests showed significant differences in log Cu between the DLB group and the control group or the AD group (p=0.008 and p=0.061, respectively).
- FIGURE 5
Relationship between (a) mini mental state examination (MMSE) score and the urge-to-cough (UTC) log–log scale slope of log Cu (where Cu=concentration of citric acid at a threshold of UTC), which illustrates significant differences; (b) comparison of the UTC log–log scale slope of log Cu among the control group, the Alzheimer's disease (AD) group and the dementia with Lewy bodies (DLB) group. There was no significant difference amongst the three groups (p=0.111).
Tables
- TABLE 1
Characteristics of patients stratified by sex
Characteristic Male Female p-value Participants n 32 39 Dementia type n Control 14 8 AD 9 21 DLB 9 10 Age years 76.47±8.27 80.24±5.62 0.02 BMI kg·m−2 22.10±3.20 21.31±3.24 0.34 Brinkman Index 413.40±430.78 13.57±44.28 <0.01 MMSE score 23.19±6.19 20.81±5.45 0.06 FEV1 % predicted 105.71±27.30 114.57±30.95 0.19 FVC % predicted 91.36±18.93 91.66±24.46 0.68 FEV1/FVC % 75.56±10.80 80.21±13.24 0.04 FEV1/FVC % predicted 118.91±15.86 112.50±18.58 0.1 pH 7.41±0.03 7.41±0.02 0.92 PaO2 mmHg 86.94±13.74 87.72±7.95 0.39 PaCO2 mmHg 39.10±3.90 39.86±3.40 0.58 HCO3− mmol·L−1 24.48±2.76 24.97±2.20 0.34 Data are presented as mean±sd unless otherwise stated and were analysed using the Mann–Whitney test. p-Values in bold express significant difference (p<0.05). AD: Alzheimer's disease; DLB: dementia with Lewy bodies; BMI: body mass index; MMSE: mini mental state examination; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; PaO2: arterial oxygen tension; PaCO2: arterial carbon dioxide tension.
- TABLE 2
Comparison of cough between male and female subjects
Characteristic Male Female p-value Patients n 32 39 Dementia type n Control 14 8 AD 9 21 DLB 9 10 C2 log g·L−1 0.97±0.47 0.90±0.52 0.27 C5 log g·L−1 1.16±0.51 1.10±0.49 0.5 Cu log g·L−1 0.40±0.43 0.42±0.49 0.9 UTC slope 1.00±0.66 1.03±0.72 0.99 Data are presented as mean±sd unless otherwise stated and were analysed using the Mann–Whitney test. p-Values less than 0.05 were deemed to represent significant difference. AD: Alzheimer's disease; DLB: dementia with Lewy bodies; Cx: lowest concentration of inhaled citric acid that could induce ≥x coughs; Cu: concentration of citric acid at a threshold of UTC; UTC: urge-to-cough.
- TABLE 3
Patients characteristics in the three study groups
Characteristic Control AD DLB p-value p1-value Patients n 22 30 19 Sex (M/F) n/n 14/8 9/21 9/10 Age years 76.64±6.37 80.40±6.43 77.67±8.70 0.146 0.257 BMI kg·m−2 22.08±3.53 21.62±2.92 21.26±3.45 0.732 0.852 Brinkman Index 340.12±462.08 110.19±221.91 146.63±323.86 0.063 0.349 MMSE score 27.82±2.24 19.69±4.50 19.25±6.25 <0.001 <0.001 FEV1 % predicted 109.66±19.91 119.33±33.03 95.48±29.62 0.039 0.117 FVC % predicted 91.65±22.25 98.18±19.93 79.33±20.66 0.025 0.064 FEV1/FVC % 80.91±10.66 75.86±12.10 77.72±14.65 0.363 0.095 FEV1/FVC % predicted 121.37±12.89 110.70±17.15 115.56±22.07 0.104 0.151 pH 7.41±0.02 7.41±0.02 7.42±0.03 0.193 0.076 PaO2 mmHg 89.06±10.12 85.81±11.59 88.30±10.46 0.567 0.514 PaCO2 mmHg 39.57±4.18 39.29±3.90 39.89±2.02 0.879 0.683 HCO3− mmol·L−1 24.44±1.62 24.56±2.87 25.58±2.39 0.389 0.353 Data are presented as mean±sd unless otherwise stated and were analysed using one-way ANOVA (p-values) or using two-way ANOVA when adjusting for gender (p1-values). Values are in bold show where significant differences were expressed (p<0.05 or p1<0.05). AD: Alzheimer's disease; DLB: dementia with Lewy bodies; BMI: body mass index; MMSE: mini mental state examination; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; PaO2: arterial oxygen tension; PaCO2: arterial carbon dioxide tension.
- TABLE 4
Comparison of cough among the three study groups
Characteristic Control AD DLB p-value p1-value Patients n 22 30 19 Sex (M/F) n/n 14/8 9/21 9/10 C2 log g·L−1 0.73±0.44 0.89±0.44 1.22±0.52 0.003 0.002 C5 log g·L−1 0.89±0.49 1.07±0.39 1.46±0.49 0.001 0.0004 Cu log g·L−1 0.24±0.45 0.36±0.37 0.67±0.52 0.008 0.004 UTC slope 1.23±0.70 1.02±0.78 0.75±0.40 0.083 0.116 Data are presented as mean±sd and were analysed using one-way ANOVA (p-values) or using two-way ANOVA when adjusting for gender (p1-values). Values in bold show where significant differences were expressed (p<0.05 or p1<0.05). AD: Alzheimer's disease; DLB: dementia with Lewy bodies; Cx: lowest concentration of inhaled citric acid that could induce ≥x coughs; Cu: concentration of citric acid at a threshold of UTC; UTC: urge-to-cough.
