None listed
Conditions
Brief summary
People with type 2 diabetes are at increased risk of developing arterial disease. Arteries stiffen with advancing age and this process is exacerbated in type 2 diabetes and other risk factors for heart disease. Increasing stiffness of arteries in the brain may impede regional blood flow, thus impairing brain function; those with poor mental abilities appear to have stiffer blood vessels in the brain compared to healthy individuals. This may account for the increased prevalence of cognitive decline associated with type 2 diabetes. However, no studies have yet investigated whether arterial function in the brain is related to the mental abilities of adults with type 2 diabetes. This project will be the first of its kind to evaluate whether artery stiffness in the brain and biomarkers of insulin resistance and type 2 diabetes are indicators of impaired mental abilities, such as attention, concentration and memory. The introduction transcranial Doppler ultrasound (TCD) enables us to readily assess the pulsatility of blood flow in the middle cerebral artery, a measure of arterial stiffness in the brain. Moreover, we will also measure cerebrovascular responsiveness (CVR), i.e. the ability of blood vessels in brain regions to dilate in response to psychological stimuli. Thus, at the same time as evaluating the cognitive abilities of people with type 2 diabetes, we can assess the ability of their arteries to supply more blood to the brain during the mental tests. We will compare these capabilities in type 2 diabetes with age and gender matched healthy controls. We will also examine their relationship to indicators of the severity of diabetes, viz. insulin resistance and glycated haemoglobin. We hypothesise that a) cerebral blood flow pulsatility will be higher and CVR to cognitive stimuli will be lower in type 2 diabetes patients than in healthy controls; b) both measures will correlate with the severity of insulin resistance/diabetes and the extent of cognitive decline. The results will indicate the extent to which impaired artery function in the brain is a potential risk factor for decline in mental abilities in type 2 diabetes and will help us to devise early intervention strategies to prevent future loss of mental abilities in this at-risk population.
Interventions
The aim of this pilot cross-sectional study involving type 2 (non-insulin-dependent) diabetic adults and age and gender matched healthy controls is to:
(1) Evaluate cognitive performance and cerebral blood flow pulsatility (both at rest and in response to a cognitive task) in type 2 diabetes patients and in healthy controls
(2) Explore relationships between cerebral blood flow pulsatility, cognitive performance and biomarkers of insulin resistance and diabetes.
Methods and Procedures:
Subject r
The aim of this pilot cross-sectional study involving type 2 (non-insulin-dependent) diabetic adults and age and gender matched healthy controls is to: (1) Evaluate cognitive performance and cerebral blood flow pulsatility (both at rest and in response to a cognitive task) in type 2 diabetes patients and in healthy controls (2) Explore relationships between cerebral blood flow pulsatility, cognitive performance and biomarkers of insulin resistance and diabetes. Methods and Procedures: Subject recruitment: Participants will be recruited from the Hunter Region in NSW using media advertising approved by the University of Newcastle Media and Marketing Department. Recruitment flyers will also be placed on noticeboards at the University of Newcastle. Participants will also be recruited from the Hunter Medical Research Institute (HMRI) Volunteer Register. Part A Potential participants will attend a local Hunter Pathology branch to have their fasting plasma glucose levels tested to determine their eligibility before visiting the HMRI. At this visit, anthropometric measurements, i.e. height, weight and waist circumference, and blood pressure and arterial compliance will be assessed. Cognitive status will then be assessed with the Mini Mental State Examination (MMSE) instrument (to screen for potential dementia). Participants scoring less than 25 will be excluded at this stage. Participants will then be fitted with a headpiece with two ultrasound probes on both sides of the temporal region. The transcranial Doppler (TCD) device will monitor the blood flow velocity in both the middle cerebral artery. Participants will be excluded if no measurable signal is obtained after 30 minutes. Eligible participants will then proceed to have their cerebral blood flow velocity recorded at rest in a seated position after 10 mins of silence. Participants will then perform a series of cognitive tasks continuously for approximately 60 mins, whilst the TCD device records changes in blood flow. Part B Ten eligible volunteers from each group that have completed Part A will be invited to return to the Research Centre a week later for reassessment of the TCD at rest and during performance of the cognitive tasks to determine the reproducibility of these outcomes.
Sponsors
Prof Peter Howe
Eligibility
Sex/Gender
All
Age
50 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
1. Age 50 – 80 years, females must be post-menopausal (self-reported cessation of menses for at least 12 months) 2. Have non-insulin-dependent diabetes as diagnosed by a doctor and fasting plasma glucose greater than or equal to 7.0mM or have fasting plasma glucose less than or equal 5.5mM, determined by the results obtained in the Hunter Pathology test.
Exclusion criteria
1. Unwilling to fast for at least 8 hours 2. A smoker or currently on nicotine therapy 3. Have dementia or suspected dementia (MMSE score less than 25 at screening visit) 4. Have a history of serious head injury, alcoholism, stroke and/or neurological condition 5. Have no measurable TCD ultrasound signal (determined during the screening visit) 6. Unable to read and write English fluently 7. Have changed their diabetes medication in the last three months
Outcome results
None listed