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result(s) for
"Howe, Peter R.C."
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Eicosapentaenoic and docosahexaenoic acids, cognition, and behavior in children with attention-deficit/hyperactivity disorder: A randomized controlled trial
by
Coates, Alison M.
,
Howe, Peter R.C.
,
Buckley, Jonathan D.
in
Attention
,
Attention - drug effects
,
Attention Deficit Disorder with Hyperactivity
2012
To determine the effects of an eicosapentaenoic acid (EPA)–rich oil and a docosahexaenoic acid (DHA)–rich oil versus an ω-6 polyunsaturated fatty acid–rich safflower oil (control) on literacy and behavior in children with attention-deficit/hyperactivity disorder (ADHD) in a randomized controlled trial.
Supplements rich in EPA, DHA, or safflower oil were randomly allocated for 4 mo to 90 Australian children 7 to 12 y old with ADHD symptoms higher than the 90th percentile on the Conners Rating Scales. The effect of supplementation on cognition, literacy, and parent-rated behavior was assessed by linear mixed modeling. Pearson correlations determined associations between the changes in outcome measurements and the erythrocyte fatty acid content (percentage of total) from baseline to 4 mo.
There were no significant differences between the supplement groups in the primary outcomes after 4 mo. However, the erythrocyte fatty acid profiles indicated that an increased proportion of DHA was associated with improved word reading (r = 0.394) and lower parent ratings of oppositional behavior (r = 0.392). These effects were more evident in a subgroup of 17 children with learning difficulties: an increased erythrocyte DHA was associated with improved word reading (r = 0.683), improved spelling (r = 0.556), an improved ability to divide attention (r = 0.676), and lower parent ratings of oppositional behavior (r = 0.777), hyperactivity (r = 0.702), restlessness (r = 0.705), and overall ADHD symptoms (r = 0.665).
Increases in erythrocyte ω-3 polyunsaturated fatty acids, specifically DHA, may improve literacy and behavior in children with ADHD. The greatest benefit may be observed in children who have comorbid learning difficulties.
Journal Article
DHA-rich fish oil lowers heart rate during submaximal exercise in elite Australian Rules footballers
by
Howe, Peter R.C.
,
Buckley, Jonathan D.
,
Murphy, Karen J.
in
Athletes
,
Australian football
,
Blood pressure
2009
Omega-3 fatty acids (n-3) can improve cardiovascular (CV) function. This study examined the effects of n-3 on endurance performance, recovery and CV risk factors in elite Australian Rules football players. 25 players were randomised, double-blind, to 6
g/day of docosahexaenoic acid (DHA)-rich fish oil (FO;
n
=
12) or sunflower oil (SO;
n
=
13) during 5 weeks of training. At baseline erythrocyte n-3 content, resting blood pressure (BP), fasting serum triglycerides (TG) and heart rate (HR) during treadmill running at 10
km/h were assessed. Two treadmill runs (T1 and T2) to exhaustion, separated by 5
min, were then performed at the average speed for a recent 2200
m time-trial. After 5 weeks, erythrocyte n-3 increased (FO 3.8
±
0.6%, SO 0.6
±
0.3%;
P
<
0.001) while TG (FO −0.32
±
0.09
mmol
l
−1, SO 0.08
±
0.05
mmol
l
−1;
P
<
0.001), diastolic BP (FO 1.3
±
1.3
mmHg, SO 6.8
±
1.7
mmHg;
P
=
0.04) and HR during submaximal exercise (FO −7.8
±
2.3
beats
min
−1, SO −1.9
±
1.9
beats
min
−1;
P
=
0.03) decreased in FO compared with SO. Time to exhaustion (TTE) during T1 increased by Week 5 (FO 10.2
±
2.2%, SO 17.3
±
4.3%;
P
<
0.001 for time). Recovery (TTE for T2 as % T1) decreased in both groups (FO, −3.4
±
4.5%, SO −8.8
±
3.9%;
P
=
0.05 for time). We conclude that 5 weeks of supplementation with FO improved CV function and reduced CV risk factors, but did not improve endurance performance or recovery in elite Australian Rules footballers.
Journal Article
Transcranial Doppler ultrasound to assess cerebrovascular reactivity: reliability, reproducibility and effect of posture
by
Howe, Peter R.C.
,
McDonnell, Michelle N.
,
Cutting, Mark A.
in
Anatomy and Physiology
,
Blood flow
,
Brain research
2013
Transcranial Doppler ultrasound (TCD) allows measurement of blood flow velocities in the intracranial vessels, and can be used to assess cerebral vasodilator responses to a hypercapnic stimulus. The reliability of this technique has not been established, nor is there agreement about whether the technique should be performed in sitting or lying postures. We tested the intra- and inter-rater reliability of measures of cerebrovascular reactivity (CVR) in 10 healthy adults, in sitting and lying postures. Participants underwent triplicate bilateral ultrasound assessment of flow velocities in the middle cerebral arteries whilst sitting and lying supine prior to and during inhalation of Carbogen (5% CO2, 95% O2) for 2 min. This procedure was performed twice by each of two raters for a total of four sessions. CVR was calculated as the difference between baseline and the peak blood flow velocity attained during CO2 inhalation. Intraclass correlation coefficients (ICCs) for intra-rater reliability were greater sitting than lying for both raters (e.g. Rater 1 ICC sitting = 0.822, lying = 0.734), and inter-rater reliability was also greater in sitting (e.g. sitting ICC = 0.504, lying = 0.081). These results suggest that assessment of CVR using TCD should be performed with participants sitting in order to maximise CVR measurement reliability.
Journal Article
Poor cerebrovascular function is an early marker of cognitive decline in healthy postmenopausal women
by
Howe, Peter R.C.
,
Wong, Rachel H.X.
,
Evans, Hamish M.
in
Cerebrovascular function
,
Cognition
,
Depression
2016
Abstract Introduction Impairment of cerebrovascular function becomes evident after menopause. No study has yet explored relationships between deficits in cerebrovascular function, cognitive performance, and mood in postmenopausal women. Method Cerebrovascular function was assessed in 80 healthy postmenopausal women by monitoring blood flow velocity (BFV) in the middle and posterior cerebral arteries using transcranial Doppler ultrasound at rest, following a hypercapnic challenge, and during performance of a cognitive test battery; the latter assessed domains of memory and executive functions. Various measures of mood (i.e., Profile of Mood States and Center for Epidemiological Studies Depression Scale) were also assessed. Results Cerebral artery elasticity and BFV responsiveness to cognitive tests (neurovascular coupling) correlated with cognitive performance but not with depressive symptoms or mood states. Mood deficits were related to poor cognitive performance. Conclusion These results highlight the importance of adequate cerebral perfusion for optimized cognitive function in healthy postmenopausal women. Preventative strategies to attenuate accelerated cognitive decline should also consider restoring cerebrovascular function.
Journal Article
No Effect of a Whey Growth Factor Extract during Resistance Training on Strength, Body Composition, or Hypertrophic Gene Expression in Resistance-Trained Young Men
by
Tomkinson, Grant R
,
Caldow, Marissa
,
Haren, Matthew T
in
Amino acids
,
Analysis
,
Body composition
2017
Growth factors can be isolated from bovine milk to form a whey growth factor extract (WGFE). This study examined whether WGFE promoted activation of the AKT/mTOR pathway enabling increased lean tissue mass and strength in resistance trained men. Forty six men with >6 months of resistance training (RT) experience performed 12 weeks of RT. Participants consumed 20 g/day of whey protein and were randomised to receive either 1.6 g WGFE/day (WGFE; n = 22) or 1.6 g cellulose/day (control, CONT; n = 24). The primary outcome was leg press one-repetition maximum (LP1-RM) which was assessed at baseline, 6 and 12 weeks. At baseline and 12 weeks body composition was assessed by dual energy x-ray absorptiometry, and muscle protein synthesis and gene expression were assessed (vastus lateralis biopsy) in a sub-sample (WGFE n = 10, CONT n = 10) pre- and 3 hr post-training. RT increased LP1-RM (+34.9%) and lean tissue mass (+2.3%; p < 0.05) with no difference between treatments (p > 0.48, treatment x time). Post-exercise P70
phosphorylation increased acutely, FOXO3a phosphorylation was unaltered. There were no differences in kinase signalling or gene expression between treatments. Compared with CONT, WGFE did not result in greater increases in lean tissue mass or strength in experienced resistance trained men.
Journal Article
Telomere shortening in elderly individuals with mild cognitive impairment may be attenuated with ω-3 fatty acid supplementation: A randomized controlled pilot study
by
Howe, Peter R.C.
,
Fenech, Michael
,
Benassi-Evans, Bianca
in
accelerated aging
,
Aged
,
Aging - drug effects
2014
Excessive shortening of the telomeric ends of chromosomes is a marker of accelerated aging. Oxidative stress and nutritional deficiency may influence this process. The aim of this study was to investigate the effect of ω-3 polyunsaturated fatty acid (ω-3 PUFA) supplementation on telomeric shortening in elderly individuals with mild cognitive impairment (MCI).
Thirty-three adults ages > 65 y with MCI were randomized to receive a supplement rich in the long-chain ω-3 PUFAs eicosapentaenoic acid (EPA; 1.67 g EPA + 0.16 g docosahexaenoic acid DHA/d; n = 12) or DHA (1.55 g DHA + 0.40 g EPA/d; n = 12), versus ω-6 PUFA linoleic acid (LA; 2.2 g/d; n = 9) for 6 mo.
The intervention did not show an increase in telomere length with treatment and there was a trend toward telomere shortening during the intervention period. Linear mixed modeling produced a robust model although statistically underpowered. Telomere shortening was greatest in the LA group (d = 0.21) than in the DHA (d = 0.12) and EPA groups (d = 0.06). Increased erythrocyte DHA levels were associated with reduced telomere shortening (r = −0.67; P = 0.02) in the DHA group.
Telomeric shortening may be attenuated by ω-3 PUFA supplementation, requiring further investigation in larger samples.
Journal Article
Monitoring athletic training status using the maximal rate of heart rate increase
by
Howe, Peter R.C.
,
Thomson, Rebecca L.
,
Buckley, Jonathan D.
in
Adult
,
Athletic performance
,
Athletic Performance - physiology
2016
Reductions in maximal rate of heart rate increase (rHRI) correlate with performance reductions when training load is increased. This study evaluated whether rHRI tracked performance changes across a range of training states.
Prospective intervention.
rHRI was assessed during five min of cycling at 100W (rHRIcyc) and running at 8km/h (rHRIrun) in 13 male triathletes following two weeks of light-training (LT), two weeks of heavy-training (HT) and a two-day recovery period (RP). A five min cycling time-trial assessed performance and peak oxygen consumption (V˙O2peak).
Performance likely decreased following HT (Effect size±90% confidence interval=−0.18±0.09), then very likely increased following RP (0.32±0.14). rHRIcyc very likely decreased (−0.48±0.24), and rHRIrun possibly decreased (−0.33±0.48), following HT. Changes in both measures were unclear following RP. Steady-state HR was almost certainly lower (−0.81±0.31) during rHRIcyc than rHRIrun. A large correlation was found between reductions in performance and rHRIrun (r±90%; CI=0.65±0.34) from LT to HT, but was unclear for rHRIcyc. Trivial within-subject correlations were found between rHRI and performance, but the strength of relationship between rHRIrun and performance was largely associated with V˙O2peak following LT (r=−0.58±0.38).
Performance reductions were most sensitively tracked by rHRIrun following HT. This may be due to rHRIrun being assessed at a higher intensity than rHRIcyc, inferred from a higher steady-state HR and supported by a stronger within-subject relationship between rHRIrun and performance in individuals with a lower V˙O2peak, in whom the same exercise intensity would represent a greater physiological stress. rHRI assessed at relatively high exercise intensities may better track performance changes.
Journal Article
Impact of cocoa flavanol consumption on blood pressure responsiveness to exercise
by
Coates, Alison M.
,
Howe, Peter R. C.
,
Buckley, Jonathan D.
in
Beverages
,
Biological and medical sciences
,
Blood pressure
2010
Impaired endothelial vasodilatation may contribute to the exaggerated blood pressure (BP) responses to exercise in individuals who are overweight/obese. The present study investigated whether consumption of cocoa flavanols, which improve endothelium-dependent flow-mediated dilatation (FMD), can modify BP responsiveness to exercise. Twenty-one volunteers (eight females and thirteen males, 54·9 (se 2·2) years, BMI 31·6 (se 0·8) kg/m2, systolic BP 134 (se 2) mmHg, diastolic BP (DBP) 87 (se 2) mmHg) were randomised to consume single servings of either a high-flavanol (HF, 701 mg) or a low-flavanol (LF, 22 mg) cocoa beverage in a double-blind, cross-over design with 3–7-d washout between treatments. Two hours after cocoa consumption, FMD was measured, followed by continuous beat-to-beat assessment (Finapres™) of BP before and during 10 min of cycling at 75 % of age-predicted maximum heart rate. Averaged data from two assessments on each type of beverage were compared by analysis of covariance using pre-exercise BP as the covariate. Pre-exercise BP was similar after taking LF and HF (153 (se 3)/88 (se 3) v. 153 (se 4)/87 (se 2) mmHg, respectively, P>0·05). However, the BP response to exercise (area under BP curve) was attenuated by HF compared with LF. BP increases were 68 % lower for DBP (P = 0·03) and 14 % lower for mean BP (P = 0·05). FMD measurements were higher after taking HF than after taking LF (6·1 (se 0·6) % v. 3·4 (se 0·5) %, P < 0·001). By facilitating vasodilation and attenuating exercise-induced increases in BP, cocoa flavanols may decrease cardiovascular risk and enhance the cardiovascular benefits of moderate intensity exercise in at-risk individuals.
Journal Article
Combination chemotherapy with cyclophosphamide, epirubicin and 5-fluorouracil causes trabecular bone loss, bone marrow cell depletion and marrow adiposity in female rats
by
Xian, Cory J.
,
Howe, Peter R. C.
,
Georgiou, Kristen R.
in
Adiposity - drug effects
,
Animals
,
Antineoplastic Combined Chemotherapy Protocols - adverse effects
2016
The introduction of anthracyclines to adjuvant chemotherapy has increased survival rates among breast cancer patients. Cyclophosphamide, epirubicin and 5-fluorouracil (CEF) combination therapy is now one of the preferred regimens for treating node-positive breast cancer due to better survival with less toxicity involved. Despite the increasing use of CEF, its potential in causing adverse skeletal effects remains unclear. Using a mature female rat model mimicking the clinical setting, this study examined the effects of CEF treatment on bone and bone marrow in long bones. Following six cycles of CEF treatment (weekly intravenous injections of cyclophosphamide at 10 mg/kg, epirubicin at 2.5 mg/kg and 5-flurouracil at 10 mg/kg), a significant reduction in trabecular bone volume was observed at the metaphysis, which was associated with a reduced serum level of bone formation marker alkaline phosphatase (ALP), increased trends of osteoclast density and osteoclast area at the metaphysis, as well as an increased size of osteoclasts being formed from the bone marrow cells ex vivo. Moreover, a severe reduction of bone marrow cellularity was observed following CEF treatment, which was accompanied by an increase in marrow adipose tissue volume. This increase in marrow adiposity was associated with an expansion in adipocyte size but not in marrow adipocyte density. Overall, this study indicates that six cycles of CEF chemotherapy may induce some bone loss and severe bone marrow damage. Mechanisms for CEF-induced bone/bone marrow pathologies and potential preventive strategies warrant further investigation.
Journal Article
Food groups and fatty acids associated with self-reported depression: An analysis from the Australian National Nutrition and Health Surveys
by
Howe, Peter R.C.
,
Kreis, Irene A.
,
Kolanu, Nithin
in
acid value
,
administration & dosage
,
Adolescent
2013
The aim of this study was to explore the associations between incidence of depression and dietary intakes of foods and fatty acids in adult Australians.
Data from the 1995 Australian National Nutrition Survey (NNS), the 1995 Australian National Health Survey (NHS) and an updated fatty acid database were merged and the 24-h fatty acid intakes were calculated for the 10 986 adult participants ages 18 to 79 y in the 1995 NNS. The merged data set was used to run a logistic regression with depression as the response variable and the food groups and calculated fatty acid values, age, and sex as predictors.
The regression model indicated that increased intakes per kilojoule of meat, poultry, and game; vegetables; and eicosapentaenoic acid (EPA) are associated with lower odds of having depression, whereas increased intakes of non-alcoholic beverages, milk products and dishes, and docosapentaenoic acid (DPA) are associated with an increase in the odds of having depression. The results confirm a collective effect of diet on mood. Although other studies have shown that fish consumption is associated with lower odds of depression, this study showed lower odds of depression with high meat consumption, possibly reflecting the fact that Australians consume six times more meat than fish.
Significant associations between food and mood identified in this study warrant further research to determine causality.
Journal Article