Article Cognitive Change in Heart Failure: A Systematic Review
As a matter of fact, there are hundreds, if not thousands of paper, examining the link between heart and lung function and cognitive functioning (largely executive functioning) in the elderly. If you looking for an exact year in which all these studies began, you need to plough though all systemic reviews that had been done.
Actually, I have done a study exploring the association between lactate kinetics during rest and maximal steady state (MLSS) and cardiorespiratory fitness (CRF) with cognitive function. There are some hypothesizes suggesting produced lactate after physical activity as a hormone that impact brain plasticity and therefore improve cognitive function. Therefore, it is hypothesized that who has a better lactate kinetic during rest or exercise should has a better brain activity.
But, there are hypothesizes that CRF does as well.
So, I have done a study to dissociate this in a sample of young adults (n=80).
please, read the following papers
who was the first explored the association between CRF and cognition?
You might want to have a look at Hillman, C. H., Erickson, K. I., & Kramer, A. F. (2008). Be smart, exercise your heart: exercise effects on brain and cognition. Nature reviews neuroscience, 9(1), 58. ( http://drlardon.com/wp-content/uploads/2014/06/Perspectives.pdf )
Hillman, Erickson and Kramer have done extensive research in the relationship between cardiorespiratory fitness and cognition across the lifespan; so, I am sure you will find their literature interesting.
Looking back to when it all started, you might get to the ancient Greek society, but for a more recent systematic investigation of the topic, perhaps you will find interesting the literature by Spirduso (80's), although there is something available already from the 50's. For further review of the history of this field of research i suggest you read Etnier JL, Shih C-H, Piepmeier AT. The History of Research on Chronic Physical Activity and Cognitive Performance. Exercise-Cognition Interaction. Elsevier; 2016. p. 29-42.