Orienting network dysfunction in progressive multiple sclerosis.
affects up to 70% of the population . The most frequently impaired
domains are memory, processing speed and attention. Three main
attentional networks were described: the alerting network responsible
for controlling vigilance and performance during tasks, the orienting
network in charge of orientation to external stimuli, and the executive
control network that deals with solving conflicts, detecting targets,
and focal attention. The evaluation of these networks is possible by
the means of the Attention Network Test (ANT). To our knowledge,
this test has been studied in patients with relapsing–remitting MS
(RRMS) but not in MS patients with progressive subtypes. We
postulated that the increase in lesion load and cerebral atrophy
throughout disease progression might have more impact on the attentional
capacities in progressive MS.
(MRT: 816.84 ± 142.8 vs 683.5 ± 93.1; p = 0.0006), and less accurate
(MA 94.2 ± 9.4 vs 97.7 ± 5.8; p = 0.002) than their healthy counterparts.
Looking at the network effect, MS patients had a significant deficit
in the orienting network (54.2 ± 55.5 vs. 24.9 ± 29.4; p = 0.047), but
not in the alerting (24.0 ± 32.1 vs. 27.3 ± 26.5; p = 0.53) or the executive
control (159.1 ± 74.9 vs. 134.5 ± 37.7; p = 0.23) networks.
The key is the amount of invested effort in terms of brain power which is required to maintain this network, with a constant recruitment of mental resources for post-production executive monitoring (i.e. what the heck am I seeing?) and preparatory processes for on-going monitoring (i.e. for continued ogling!). Impaired memory, and in particular, processing speed probably has a significant impact on high-load tasks such as this.