The assessment of cognitive function in the German National Cohort (NAKO) – Associations of demographics and psychiatric symptoms with cognitive test performance

Abstract

Objectives

To describe the cognitive test battery of the German National Cohort (NAKO), a population-based mega cohort of 205,000 randomly selected participants, and to examine associations with demographic variables and selected psychiatric and neurological conditions.

Methods

Initial data from 96,401 participants providing data on the cognitive performance measured by a brief cognitive test battery (12-word list recall task, semantic fluency, Stroop test, digit span backwards) was examined. Test results were summarised in cognitive domain scores using exploratory and confirmatory factor analyses. Associations with sociodemographic and psychiatric factors were analysed using linear regression and generalised additive models.

Results

Cognitive test results were best represented by two domain scores reflecting memory and executive functions. Lower cognitive functions were associated with increasing age and male sex. Higher education and absence of childhood trauma were associated with better cognitive function. Moderate to severe levels of anxiety and depression, and a history of stroke, were related to lower cognitive function with a stronger effect on executive function as compared to memory. Some associations with cognition differed by German language proficiency.

Conclusions

The NAKO cognitive test battery and the derived cognitive domain scores for memory and executive function are sensitive measures of cognition.

KEYWORDS:

• Cognition
• German National Cohort
• NAKO
• depression
• cognitive ageing
• confirmatory factor analysis

Acknowledgments

We thank all study participants, and staff at the NAKO study centres, the data management and integration centre, and the NAKO head office who enabled the conduction of the study and made the collection of all data possible.

Statement of interest

HJG has received travel grants and speakers honoraria from Fresenius Medical Care, Neuraxpharm, Servier and Janssen Cilag as well as research funding from Fresenius Medical Care. MJH and SC report employment by the Helmholtz Centre for Infection Research.

Additional information

Funding

The German National Cohort (NAKO) (www.nako.de) is funded by the Federal Ministry of Education and Research (project numbers: 01ER1301A/B/C and 01ER1511D), the federal states, and the Helmholtz Association, with additional financial support from the participating universities and the participating institutes of the Leibniz Association and the Helmholtz Association. This work was supported by the German Federal Ministry of Education and Research (BMBF) through ERA-NET NEURON, “SynSchiz - Linking synaptic dysfunction to disease mechanisms in schizophrenia - a multilevel investigation “[01EW1810 to MR], through ERA-NET NEURON “Impact of Early life MetaBolic and psychosocial strEss on susceptibility to mental Disorders; from converging epigenetic signatures to novel targets for therapeutic intervention” [01EW1904 to MR].