The project aimed to place cognitive psychology in the context of 21st century cognitive neuroscience by integrating research traditions in experimental cognitive psychology, brain imaging and molecular genetics. The framework for integration was a multilevel approach focusing first on the cognitive neurogenetics of attention and memory, then examining the dynamics of brain-cognition-genetics interaction in an adult lifespan perspective, and finally including aspects of cognitive pathologies. Cognitive pathologies are often associated with age specific vulnerability and should therefore be studied as an integral aspect of the dynamic brain-cognition interaction within the aging perspective.

We participated in consortia combining large international databases from Norway, Sweden, UK and USA to study the genetic basis for intelligence and brain structure.

Technological advances have made it possible to analyse large amounts of genetic data efficiently. A Genomewide Association Scan (GWAS) can give information of 600 000 genetic variants or more on an individual basis. This staggering amount of data necessitates a high number of study participants (tens of thousands) to yield reliable results, which can only be achieved by combining data from several centres. GWAS is also a theoretical approach which may have the advantage of pointing out new avenues of research or narrowing down a range of alternatives for further study and replication.

Another strategy, which may allow for stronger interpretations of results, is to start with identification of a target cognitive system with well characterised human, animal and neurobiological models, and then generate hypotheses about which neurobiological systems would be the most significant sources of variation. This approach has been followed by several group members and was further developed in the CAS project, where we focussed on attention systems and their known neurochemical modulators, and then proceeding to study of a selected set of relevant genes.

The insights achieved are represented by the 10 papers published during the CAS period and papers in progress. We would especially point to our participation in major international efforts to address two issues of critical importance, i.e. the genetic basis of intelligence and the genetic basis of brain structure. Through the ENIGMA consortium for analysing the genetic basis of brain structure we are co-authors on two papers in Nature Genetics, the top ranking international journal in genetics. The general lesson learned is that a large number of genes each make a small contribution to complex traits.

We have collaborated on the problems addressed in the CAS project for several years, but CAS has provided a unique opportunity to intensify our efforts. The time at CAS has produced a wealth of new results and methodological advances that will keep us busy in several years to come. We are grateful for the excellent administrative support provided by the CAS staff during the whole project period.