Differential effects of age and executive functions on the resolution of the contingent negative variation: a reexamination of the frontal aging theory.

The "frontal aging theory" assumes the deterioration of executive/inhibitory functions as causal factors for the cognitive decline in human aging. The contingent negative variation resolution (CNV-R) is an electroencephalographic potential elicited after the second (informative) stimulus in warned Go/NoGo tasks requiring a response to one type of stimulus (Go) but not to the other (NoGo). Whereas the CNV-R across conditions is a measure of executive functions, the augmented potential in the NoGo condition is a specific measure of inhibitory processes. The aim was to examine the presumed linkage between executive processes and the CNV-R with special regard to inhibition in the NoGo condition, and to test whether any effects of age on this potential can be explained by a failure of (inhibitory) executive functions. Nineteen young and 15 elderly non-demented healthy volunteers were examined in a Go/NoGo CNV-R paradigm and on a test of executive functions focussed on set shifting (Trail Making test). Results showed: (1) Better executive functions are associated with higher amplitudes of the CNV-R across conditions. (2) The CNV-R is higher for elderly than younger subjects; this increment is much stronger in the NoGo condition. In conclusion, the CNV-R across conditions reflects executive processes such as the shift of motor set. A higher CNV-R for elderly subjects (particularly of the inhibition-related NoGo CNV-R) indicates that this group is not impaired in the available amount of executive control but may exert such control for task demands where young subjects do not require it.