The Effects of Specialty Coffee on Cognitive Function in People With Type 2 Diabetes

The Effects of CGA-rich Coffee on Cognitive Function in Type 2 Diabetes: A Parallel Groups Randomised Controlled Trial

Coffee has been found to have beneficial effects on cognitive function and blood sugar control. Benefits include reduced risk of cognitive decline and improved performance on cognitive tests, as well as reduced risk of diabetes and improved blood sugar control in people with diabetes, a population that is at a higher risk of cognitive decline. These effects have been observed for both caffeinated and decaffeinated coffee, and have been associated with the polyphenol chlorogenic acid (CGA). This polyphenol has been found to be more bioavailable in certain coffees, known as "speciality coffee" as defined by the Specialty Coffee Association of America, depending on agriculture, roasting, and brewing method. This current project will bring together these previous findings to explore the effects of specialty coffee on cognitive function and glycaemic control in people with type 2 diabetes through a randomized control trial with two groups: a high CGA specialty coffee group and a conventional coffee control group. Participants will be quasi-randomly assigned to one of these two groups following the completion of a 4-week run-in period during which participants will consume conventional coffee only. The length of the experimental arms is 8 weeks, therefore the total length of the study is 12 weeks. At the beginning and the end of each experimental arm participants will undertake a cognitive assessment online using the Gorilla platform, and a series of questionnaires relating to health and mood measures (details in procedure). Cognitive function will also be assessed at the beginning of the 4-week run-in period.

Participants will be provided with a conventional, low CGA coffee to brew and consume which contains less CGA than the experimental arm.

Participants will be provided with a single origin, CGA-rich specialty coffee as graded by the Specialty Coffee Association of America's Q-grading system to brew and consume

Assessed at the end of 8-week intervention arm using a modified version of the Rey Auditory Verbal Learning Test

Assessed at the beginning of the 8-week intervention arm using a modified version of the Rey Auditory Verbal Learning Test

Assessed at the beginning of the 4-week run-in period using a modified version of the Rey Auditory Verbal Learning Test

Assessed at the end of the 8-week intervention arm with a computerised version of the Corsi Block Tapping Test

Assessed at the beginning of the 8-week intervention arm with a computerised version of the Corsi Block Tapping Test

Assessed at the beginning of the 4-week run-in with a computerised version of the Corsi Block Tapping Test

Assessed at the end of the 8-week intervention arm with a computerised version of the Digit Symbol Substitution Test

Assessed at the beginning of the 8-week intervention arm with a computerised version of the Digit Symbol Substitution Test

Assessed at the beginning of 4-week run-in with a computerised version of the Digit Symbol Substitution Test

Inclusion Criteria: Age 55-70 years Formal diagnosis of Type 2 Diabetes for 3 years or more Current coffee drinkers, 4 or fewer cups daily (a cup is 8 oz) Exclusion Criteria: Insulin-dependent Consuming on average more than 4 cups of coffee daily Regularly consuming specialty coffee (participants will be provided with a list of these coffees)