102 / 113
S
teiner
ABQ
et
al
.
652
R
ev
A
ssoc
M
ed
B
ras
2017; 63(7):651-655
At a Key Symposiumheld in Stockholm in the year 2003,
MCI was defined as a heterogeneous entity divided into three
categories: amnestic MCI with greater risk of AD; MCI of
multiple cognitive domains; andMCI with impairment of a
single cognitive function different frommemory.
10
Main
diagnostic points of MCI were redefined: the individual be-
ing neither normal nor demented; evidence of cognitive
declinemeasured objectively or based on subjective perception
combined with objective cognitive impairment; preservation
of basic living and complex instrumental activities or mini-
mally compromised.
10
A task force of American authorities,
led by the National Institute of Aging and the Alzheimer’s
Association, proposed a review of the criteria used for the
classification of MCI in 2011.
11
Despite the basic clinical
criteria being similar to those for MCI diagnosis, this review
opened the focus on the probable etiological mechanisms
that lead to cognitive impairment, with emphasis on early
diagnosis of AD, via the utilization of biomarkers.
The term “mild cognitive disorder” was included in
the International Classification of Diseases (ICD) to be
applied to patients that presented a decline in cognitive
performance, usually accompanied by abnormalities in
objective tests for cognitive functions, but not sufficient-
ly to fulfill the diagnostic criteria of dementia.
12
E
pidemiology
The first population-based study on the prevalence of
MCI and its subtypes (Figure 1)
13
was based on a cardio-
vascular health study.
14
The researchers applied the cri-
teria for MCI retrospectively in a cohort and found a
prevalence of 22%, of which 6% referred to the amnestic
subtype and 16% to multiple domains in patients aged
65 years or older.
15
Other studies demonstrated an inci-
dence rate from 1 to 6% per year and a prevalence of 3 to
22%.
15
The prevalence and incidence of MCI found in
Brazil was similar to rates observed in other countries.
16
In a riverside-dwelling population with low education
and practically no vascular risk factors, MCI prevalence
was 7.7%.
17
A systematic review and meta-analysis on the
prevalence of dementia among individuals aged 60 years
or older found a narrow range of 5-7% in most world
regions, with a higher prevalence in Latin America (8.5%),
and a distinctively lower prevalence in the four sub-Sa-
haran African regions (2-4%).
18
In this study, 35.6 million
people lived with dementia worldwide in 2010, with num-
bers expected to almost double every 20 years, to 65.7
million in 2030 and 115.4 million in 2050. Yet, in 2010,
58% of all people with dementia lived in countries with
low or middle incomes, with this proportion expected to
rise to 63% in 2030 and 71% in 2050.
18
P
rogression
to
AD (F
igure
2)
19
Several authors observed an increased rate of progression
toward dementia in patients with MCI.
8,20-25
However, stud-
ies have not been replicated by other researchers. One ex-
planation for this fact may arise from the observation that
memory complaints appear to have little correlation with
the performance of individuals on objective cognitive tests.
26
On the other hand, longitudinal studies revealed that
elderly individuals with recent complaints of impaired
memory performed worse in memory tests than those
who had not had such a complaint in one year of follow-
-up. They suggest that memory complaints from the el-
derly must be taken even more seriously when accompa-
nied by objective signals of cognitive deterioration.
27,28
Despite some discrepancies among studies, the research-
ers agree that individuals diagnosed with MCI develop
dementia at a faster rate than the rest of the population.
E
valuation
of memory
problems
The initial evaluation must rely on careful obtainment of
patient history and of memory complaint, always compar-
ing to previous functional state of cognitive complaint,
29
establishing a chronology for the initiation of symptoms,
as well as habits and comorbidities; investigation of mood
symptoms and behavioral alterations. Questions on dietary
and sleep habits must be posed.
30,31
Detailed neurological
and general physical exammust be carried out, with thor-
ough observation of gait and verification of motor signals
(alterations of reflexes, rigidity, bradykinesia, tremor, slow-
ness).
32
The laboratory exams that must be performed to
rule out reversible dementia syndromes include:
•
•
Thyroid hormone tests to investigate underacti-
ve thyroid.
•
•
Vitamin B12 blood test to check vitamin deficiency.
•
•
Complete blood count to investigate infections.
•
•
Aspartate aminotransferase (AST) and alanine amino-
transferase (ALT) blood tests that check liver function.
•
•
Chemistry screening to check the level of electroly-
tes in the blood and to check kidney function.
•
•
Glucose test to check the level of sugar in the blood.
•
•
VDRL and HIV.
•
•
Erythrocyte sedimentation rate, a blood test that in-
vestigates signs of inflammation in the body.
•
•
Toxicology screening, examining blood and urine.
•
•
Antinuclear antibodies, a blood test used to diagno-
se autoimmune diseases.
•
•
Investigation of heavy metals in the blood, such as a
lead test.
33
•
•
A lumbar puncture to test for certain proteins in the
spinal fluid.