The Cognition, Brain, and Aging (COBRA) project is a longitudinal study that involves scientists from ARC, Umeå University, and the Max Planck Institute for Human Development in Berlin.
COBRA follows around 180 persons who are between 63 and 67 years at baseline across nine years, with three measurement occasions. Multiple brain measures are assessed at each interval using PET and MRI (i.e., dopamine [DA] D2 receptors, markers of grey- and white-matter integrity, functional networks). Cognition is assessed using measures of working memory, episodic memory, and speed, and a comprehensive lifestyle questionnaire is administered (see A schematic representation of the design of the COBRA project).
A chief motive behind COBRA is the fact that the degree of average age-related change in DA availability, grey matter, and white matter remains unclear, due to the paucity of longitudinal data. This means that current foundations for research on aging, brain, and cognition are imperfect and possibly erroneous.
Consequently, the shared and unique contributions of changes in DA, grey matter, and white matter to changes in cognitive performance in old age are unknown. Resolving this issue is imperative, because changes in these neural substrates are likely to be related, and therefore must be assessed jointly to evaluate their relative contributions to cognitive decline in aging.
It is also unknown which of the candidate neural correlates (DA, grey matter, white matter) of cognitive decline first displays signs of change in old age. Likewise, whether one brain change is associated with subsequent changes in other brain measures, and thus acts as a primary mechanism of decline in brain and cognition remains unclear. Toward this end, our main hypothesis is that age-related DA changes precede changes in the other brain indices assessed, and serve as the most powerful antecedent of age-related cognitive changes.
Finally, the lifestyle factors associated with changes in the brain parameters assessed are largely unknown. New knowledge here is critical because identifying key lifestyle factors that modify brain and cognition in old age will inform the focus of intervention and prevention strategies.