Amongst the varied symptomology of multiple
sclerosis is to be fo und the alteration of higher
functions (cognitive deficit), which has considerable
repercussions on the quality of life of patients.
The old descriptions of the disease rarely
differentiate cognitive affectation from the more general
category of “mental symptoms”, which also includes a
broad range of affective disorders. Towards 1960
neuropsychological tests began to be employed, and it
was from the 1970s onwards that a clear distinction was
drawn between deterioration of the higher functions
and psycho-affective aspects in the disease.
The pattern of cognitive deterioration in patients
with multiple sclerosis is not uniform. During the initial
phases of the disease it is, in general, light and it has an
insidious start, although inter-individual variability is
wide, depending on the predominant pathological
alterations in the lesions and on their number and
localisation. In more severe cases, it is possible to
include within the debatable term of subcortical
dementia, intellectual slowness, problems of attention,
alterations in abstract reasoning, shortcomings in the
resolution of problems and memory dysfunction.
It is an almost invariable complication of the
advanced stages of the disease, since the lesions
characterised by axonal loss affect broad areas of
white matter, which determines the deafferentation of
several areas of cortical association.
There does not appear to be any correlation
between cognitive deterioration and the variables of
the disease considered in an independent way, such as
demographic data, clinical course, alterations of mood,
consumption of medicines or fatigue. Although,
evidently, the disease’s progressive secondary forms
of greater duration and the accumulation of lesions are
what present the greatest deterioration.
With present-day techniques of neuroimaging it
has been possible to show a correlation between
cognitive deterioration and the existence of an
increase in ventricular size, periventricular lesions and
atrophy of the callous body.