Arginine is one of the main metabolites in the brain. Research data on animals demonstrate possible arginine involvement in visuospatial memory processes functioning (Utkan et al., 2012; Hosseini et al., 2010).
We compared arginine levels (1.72, 1.90, 3.77 ppm) in hippocampi of both hemispheres and right inferior parietal cortex with neuropsychological visuospatial memory characteristics of 18 females, mean age – 58.2 years old. For each subject we performed 3T proton magnetic resonance spectroscopy. Visuospatial memory capacity, permanency and the amount of different memory errors were assessed with Luria’s neuropsychological tests. We calculated non-parametric correlations (p<0.05) between individual neuropsychological and biochemical measurements.
Visuospatial memory capacity correlates negatively (r=-0.47) with arginine (3.77 ppm) level. Furthermore, higher arginine (1.72 ppm) level is related to the increase of confabulations (r=0.58), contaminations (r=0.47) and sequence errors (r=0.64 and r=0.61 for 1.90 ppm). No significant correlations for both hippocampi were revealed.
According to the results, high arginine level in right inferior parietal cortex is related to the increased amount of different visuospatial memory errors and the decrease of visuospatial memory capacity. Our results correspond well with the Hosseini et al. (2010) study, which demonstrates that administration of arginine leads to visuospatial memory impairment in rats. Although there is no certain explanation of the revealed fact, we can suggest that either arginine itself has a negative effect on the memory processes or its increased level in the brain means that it is not utilized properly for some reason and thus visuospatial memory decline can be related to consequent deficit of the bioactive molecules, synthesized from arginine (e.g. nitric oxide or citrulline).