7 August 2013 Last updated at 23:38 GMT
Cocoa 'might prevent memory decline'
Drinking cocoa every day may help older people keep their brains healthy, research suggests.
A study of 60 elderly people with no dementia found two cups of cocoa a day improved blood flow to the brain in those who had problems to start with.
Those participants whose blood flow improved also did better on memory tests at the end of the study, the journal Neurology reported.
Experts said more research was needed before conclusions could be drawn.
It is not the first time cocoa has been linked with vascular health and researchers believe that this is in part due to it being rich in flavanols, which are thought to have an important role.
In the latest study, researchers asked 60 people with an average age of 73 to drink two cups of cocoa a day - one group given high-flavanol cocoa and another a low-flavanol cocoa - and consume no other chocolate.
Ultrasound tests at the start of the study showed 17 of them had impaired blood flow to the brain.
There was no difference between those who drank flavanol-rich cocoa and those who had flavanol-poor cocoa.
But whichever drink they were given, 88% of those with impaired blood flow at the start of the study saw improvements in blood flow and some cognitive tests, compared with 37% of people whose blood flow was normal at the beginning of the study.
MRI scans in 24 participants found that people with impaired blood flow were also more likely to have tiny areas of brain damage.
"We're learning more about blood flow in the brain and its effect on thinking skills," said study author Dr Farzaneh Sorond a neurologist at Harvard Medical School.
"As different areas of the brain need more energy to complete their tasks, they also need greater blood flow. This relationship, called neurovascular coupling, may play an important role in diseases such as Alzheimer's."
The researchers said the lack of difference between the flavanol-rich and flavanol-poor cocoa could be because another component of the drink was having an effect or because only small amounts were needed.
Dr Simon Ridley, head of research at Alzheimer's Research UK, said this was a small study but that it added to a wealth of evidence.
"A cocoa-based treatment would likely be very popular, but it's too soon to draw any conclusions about its effects.
"One drawback of this study is the lack of a control group for comparison, and we can't tell whether the results would have been different if the participants drank no cocoa at all."
But he added: "Poor vascular health is a known risk factor for dementia, and understanding more about the links between vascular problems and declining brain health could help the search for new treatments and preventions."
Neurology. 2013 Aug 7. [Epub ahead of print]
Neurovascular coupling, cerebral white matter integrity, and response to cocoa in older people.
Sorond FA, Hurwitz S, Salat DH, Greve DN, Fisher ND.
From the Department of Neurology, Stroke Division (F.A.S.), and Department of Medicine, Division of Endocrinology, Diabetes and Hypertension (S.H., N.D.L.F.), Brigham and Women's Hospital; Neuroimaging Research for Veterans Center (D.H.S.), and Geriatric Research, Education and Clinical Center (D.H.S.), VA Boston Healthcare System; MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging (D.H.S., D.N.G.), Department of Radiology, Massachusetts General Hospital; and Harvard Medical School (F.A.S., S.H., D.H.S., D.N.G., N.D.L.F.), Boston, MA.
To investigate the relationship between neurovascular coupling and cognitive function in elderly individuals with vascular risk factors and to determine whether neurovascular coupling could be modified by cocoa consumption.
Sixty older people (aged 72.9 ± 5.4 years) were studied in a parallel-arm, double-blind clinical trial of neurovascular coupling and cognition in response to 24 hours and 30 days of cocoa consumption. Cognitive measures included Mini-Mental State Examination and Trail Making Test A and B. Neurovascular coupling was measured from the beat-to-beat blood flow velocity responses in the middle cerebral arteries to the N-Back Task. In a subset of MRI-eligible participants, cerebral white matter structural integrity was also measured.
Neurovascular coupling was associated with Trails B scores (p = 0.002) and performance on the 2-Back Task. Higher neurovascular coupling was also associated with significantly higher fractional anisotropy in cerebral white matter hyperintensities (p = 0.02). Finally, 30 days of cocoa consumption was associated with increased neurovascular coupling (5.6% ± 7.2% vs -2.4% ± 4.8%; p = 0.001) and improved Trails B times (116 ± 78 seconds vs 167 ± 110 seconds; p = 0.007) in those with impaired neurovascular coupling at baseline.
There is a strong correlation between neurovascular coupling and cognitive function, and both can be improved by regular cocoa consumption in individuals with baseline impairments. Better neurovascular coupling is also associated with greater white matter structural integrity.
Hypertension. 2012 Sep;60(3):794-801. doi: 10.1161/HYPERTENSIONAHA.112.193060. Epub 2012 Aug 14.
Benefits in cognitive function, blood pressure, and insulin resistance through cocoa flavanol consumption in elderly subjects with mild cognitive impairment: the Cocoa, Cognition, and Aging (CoCoA) study.
Desideri G, Kwik-Uribe C, Grassi D, Necozione S, Ghiadoni L, Mastroiacovo D, Raffaele A, Ferri L, Bocale R, Lechiara MC, Marini C, Ferri C.
University of L'Aquila, Department of Life, Health, and Environmental Sciences, Viale S Salvatore, Delta 6 Medicina, 67100 Coppito, L'Aquila, Italy. email@example.com
Flavanol consumption is favorably associated with cognitive function. We tested the hypothesis that dietary flavanols might improve cognitive function in subjects with mild cognitive impairment. We conducted a double-blind, parallel arm study in 90 elderly individuals with mild cognitive impairment randomized to consume once daily for 8 weeks a drink containing ?990 mg (high flavanols), ?520 mg (intermediate flavanols), or ?45 mg (low flavanols) of cocoa flavanols per day. Cognitive function was assessed by Mini Mental State Examination, Trail Making Test A and B, and verbal fluency test. At the end of the follow-up period, Mini Mental State Examination was similar in the 3 treatment groups (P=0.13). The time required to complete Trail Making Test A and Trail Making Test B was significantly (P<0.05) lower in subjects assigned to high flavanols (38.10±10.94 and 104.10±28.73 seconds, respectively) and intermediate flavanols (40.20±11.35 and 115.97±28.35 seconds, respectively) in comparison with those assigned to low flavanols (52.60±17.97 and 139.23±43.02 seconds, respectively). Similarly, verbal fluency test score was significantly (P<0.05) better in subjects assigned to high flavanols in comparison with those assigned to low flavanols (27.50±6.75 versus 22.30±8.09 words per 60 seconds). Insulin resistance, blood pressure, and lipid peroxidation also decreased among subjects in the high-flavanol and intermediate-flavanol groups. Changes of insulin resistance explained ?40% of composite z score variability through the study period (partial r(2)=0.4013; P<0.0001). To the best of our knowledge, this is the first dietary intervention study demonstrating that the regular consumption of cocoa flavanols might be effective in improving cognitive function in elderly subjects with mild cognitive impairment. This effect appears mediated in part by an improvement in insulin sensitivity.
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