Join the HAVEN study

Participation in the study will require you to visit the University of Reading on two occasions, for approximately 2.5 hours each time. Information about each of the procedures in the study is provided below.

Visit 1 (approx. 2h 30 min)

Before your visit
On the day before your visit, please avoid doing strenuous exercise or drinking alcohol, and try to get a good night’s sleep. We will give you a diet diary to complete so we know what foods you have eaten on that day. We will also ask you to eat a specific meal the evening before your visit, and will provide you with the meal. On the day of your visit, it is important you don’t have anything to eat or drink (other than water) before you come in. This is because eating and drinking can affect some of the tests we need to conduct at the beginning of the visit. We will give you a meal at the end of your visit and will be able to accommodate dietary requirements.

Video study session (30 minutes)
You will watch a video of a TV programme lasting about 30 minutes. We will ask you to watch the video closely and concentrate throughout, since later you will be given a memory test involving the video.​ We are particularly interested in how your memory works, and the regions of your brain that are involved in memory.

Blood sample (15 minutes)
We will take a blood sample from your arm. We will take 30ml of blood (about 2 tbsp). This blood sample will be taken by someone who is trained and experienced to do so. We will use this blood sample to measure how your blood clots and your blood sugar, blood fat and haemoglobin levels.

Cognitive tasks (15 minutes)
This will be a test of your short-term memory – your ability to memorise things the researcher tells you. The researcher will give you a list of words and you will have to repeat the list from memory.

Brain scan (1 hour 30 minutes)
You will have a brain scan in an MRI scanner to measure your brain structure and function (MRI stands for magnetic resonance imaging). You will be in the scanner for approximately 1 hour, although we will allow 1 hour 30 min in total to make sure you have time to ask questions and feel comfortable.

• • ​Resting measures. You will first be asked to relax in the MRI scanner while a researcher takes resting measurements of your brain including brain structure and blood flow to different areas of your brain.

• • Memory test. After these measurements are complete you will be given a memory test on the video you watched earlier. You will complete this test while in the MRI scanner, and we will be able to take measurements of how your brain is functioning while you complete the test. The memory task will take about 20 minutes.

  • Visual test. Finally, you will be shown flashing images on a screen while in the MRI scanner. We will be able to take measurements of how your brain is functioning while you view the images. The visual test will take about 5 minutes.

 Visit 2 (approx. 2h)

Before your visit
On the day before your second visit, you will need to follow the same procedures as you did for your first visit. Specifically:

• • Avoid doing strenuous exercise
  • Avoid drinking alcohol
  • Try to get a good night’s sleep
  • Complete a diet diary (we will provide this)
  • Eat a specific meal the night before you visit (we will provide this)

On the day of your visit, do not eat or drink anything (other than water) before you come in. We will give you a meal at the end of your visit and will be able to accommodate dietary requirements.

Blood sample (15 minutes)
We will take a blood sample from your arm. We will take 30ml of blood (about 2 tbsp). This blood sample will be taken by someone who is trained and experienced to do so. We will use this blood sample in the same way as in Visit 1, which will allow us to determine whether and how much the measurements of interest change over time.

Blood vessel function (30 minutes)
‘Laser Doppler Imager’ (LDI) is used to measure vascular function. Two small Perspex rings containing a small amount (~2.5 ml) of two liquids will be placed on your forearm and a very small current will be applied to allow the chemicals to pass through the skin barrier (‘iontophoresis’). The chemicals stimulate the small blood vessels located under the skin to relax and increase the flow of blood. The LDI will continually monitor this response over 20 min by using a clinical laser to scan the rings on your arm. In total, LDI will take approximately 30 min per measurement.

The action of the chemicals on your blood vessels is short-term and restricted to the small area of skin (approx. 10 cm) where they are applied. The procedure is pain-free; however, it is usual for some participants to experience some redness and irritation after iontophoresis but this should only last for 10 min. Throughout the LDI measurement, participants will be required to wear suitable eye protection and the researchers will ask you to remove or cover any jewellery on your measurement arm. Creams and lotions should also not be used on your arms as this can affect the measurement.

Travel (15 minutes)
After you have had your blood taken, you will be given a meal and have time to eat and relax before the other assessments. Where possible we would like everyone eat the same meal, but we will be able to cater for dietary requirements.

Brain scan (1 hour)
You will have a brain scan in an MRI scanner to measure your brain structure and function (MRI stands for magnetic resonance imaging). You will be in the scanner for approximately 30 min, although we will allow 1 hour in total to make sure you have time to ask questions and feel comfortable.

• • ​Resting measures. You will first be asked to relax in the MRI scanner while a researcher takes resting measurements of your brain. This will be quicker than the resting measures at your first visit.

• • Brain blood vessel health. Finally, to measure your brain blood vessel health, we will test how the blood vessels in your brain respond to changes in carbon dioxide. This test will have two parts. You will need to breathe from a large bag containing slightly higher-than-normal levels of carbon dioxide (5%) for 5 minutes. You will then have to breathe faster-than-normal (30 breaths per minute) for 5 minutes, which will reduce your carbon dioxide levels to lower-than-normal.

Participation of the current study will enable you to:

• Obtain an image of your brain
• Obtain information about your body and health
• Experience what it is like to participate in a laboratory testing environment
• Contribute to scientific research into body and brain health as we age
• Contribute to the training of student researchers who are collaborating on the study

Participation in this research will have no direct health benefits for you. None of the tests or procedures in the study can be used for the purposes of diagnosing or managing illness.

What are the risks of taking part?

There are some risks associated with participating in this study. These risks are:

Common (about 25% chance)

• Blood vessel function test – Redness or itching
  During this technique, a weak electrical current will deliver drugs to your skin blood vessels.  This non-invasive technique is safe, but sometimes causes brief redness or itching which will go away within 20–30 minutes after the procedure.

Less Common (less than 10% chance)

• Blood sample – bruising
  There is a chance (about 1 in 50) that venous blood sampling may leave a bruise on your arm. The risk of this will be minimised because the researcher taking your blood will be trained and experienced.

Rare (less than 1% chance)

• Brain scan – breathing higher-than-normal levels of carbon dioxide
  This can result in short-term and mild side effects. These include nausea, flushing, hyperventilation (breathing faster than normal), anxiety, sensory stimulation, and feelings of panic. To reduce these risks, trained staff will monitor you for these symptoms before, during, and after this test, and will stop the test if you begin to experience any of these symptoms.
• ​Brain scan – claustrophobia
  The MRI scanner is a confined space, and it is possible you may suffer psychological stress, anxiety, or claustrophobia. The risk is expected to be 1 in 200 (0.5%). If you know you suffer from claustrophobia we will not complete an MRI scan on you. Whilst you are in the scanner, we will provide you with a panic button which you can press to stop the scan at any time. There is more information about what it is like to have an MRI scan in the MRI Participant Information Sheet which you have received alongside this information.