Objectives. The aim of the study was to investigate the relationship between vitamin B12 serum levels and cognitive performance in different types of dementia: Alzheimer's Disease, Vascular Dementia and Mixed Dementia. Considering the more and more often emphasized need for taking into account both the cultural background and genetic differences in the research on physiology of cyanocobalamine, participants in the study (222 patients with dementia) represented the Polish population.
Method. In this cross-sectional study utilizing the ex-post facto paradigm the main independent variable was the vitamin B12 blood serum level, laboratory measured in pg/l. The dependent variable was the patients' cognitive performance (measured using the MMSE) and their nosological diagnosis. Gender was adjusted for as an extraneous variable.
Results. In the statistical analyses no significant relationships were found between the vitamin B12 serum level, cognitive performance and dementing diseases including Alzheimer's Disease, Vascular Dementia and Mixed Dementia. An interesting finding was that gender differentiated the relationship between the cyanocobalamine serum level and the type of dementing disease. The results show that male patients with Vascular Dementia as compared to those with Alzheimer's Disease had not only significantly lower vitamin B12 serum levels, but also significantly better cognitive performance.
Conclusions. No relationship between vitamin B12 deficiency, cognitive performance and type of dementia was found in patients with Alzheimer's Disease, Vascular Dementia and Mixed Dementia. In the research on relation between cyanocobalamine serum levels and the progression of the dementing process the effect of gender should be taken into account. The research method needs improvement, especially as regards the sample selection and cognitive performance assessment. The obtained findings require replication.