Multiple Sclerosis and Healthy Aging: a Comparative Analysis of Structure and Function
Abstract
Abstract
The relationship between healthy, normal aging and the neurodegenerative disease Multiple
Sclerosis (MS) is a subject of ongoing debate. Parallels between the two include vascular and
metabolic decline in addition to cognitive decline. In particular, processing speed declines are
seen in both aging and MS. In aging, previous work has suggested that processing speed decline
is thought to be the basis for all age-related cognitive decline. Whereas neurovascular and
neurovascular effects of MS and aging have previously been studied separately, they have not
been studied in parallel. In addition, the relationships between these effects and MS- and age-
related cognitive decline have not previously been investigated. In the studies presented here, I
explore the relationships between neurovascular and neurometabolic function in aging and in MS
as well as their effects on cognitive and brain volume using multiple regression analysis. I found
that cerebrovascular reactivity is associated with cognitive decline in aging, but not in MS,
despite significantly lower arterial reactivity in MS. I also found that task-evoked neurovascular
and neurometabolic dynamics are associated with brain volume in MS, but not in aging. Lastly, I
do not find any relationships between processing speed and white matter integrity in any group.
These results indicate that processing speed decline is a diffuse phenomenon that can arise from
the dysfunction of many different systems. It is also indicative of divergent effects of vascular
pathology and signaling dysfunction on MS patients and older adults. This work shows that
despite similarities in pathological processes, vascular and metabolic associations with cognitive
decline and brain volume differ between MS and aging.