The diagnosis of normal cognition or dementia in the Brazilian Brain Bank of the
Aging Brain Study Group (BBBABSG) has relied on postmortem interview with an
informant.ObjectivesTo ascertain the sensitivity and specificity of postmortem diagnosis based on
informant interview compared against the diagnosis established at a memory
clinic.MethodsA prospective study was conducted at the BBBABSG and at the Reference Center
for Cognitive Disorders (RCCD), a specialized memory clinic of the Hospital
das Clínicas, University of São Paulo Medical School. Control
subjects and cognitively impaired subjects were referred from the Hospital
das Clínicas to the RCCD where subjects and their informants were
assessed. The same informant was then interviewed at the BBBABSG.
Specialists’ panel consensus, in each group, determined the final diagnosis
of the case, blind to other center’s diagnosis. Data was compared for
frequency of diagnostic equivalence. For this study, the diagnosis
established at the RCCD was accepted as the gold standard. Sensitivity and
specificity were computed.ResultsNinety individuals were included, 45 with dementia and 45 without dementia
(26 cognitively normal and 19 cognitively impaired but non-demented). The
informant interview at the BBBABSG had a sensitivity of 86.6% and
specificity of 84.4% for the diagnosis of dementia, and a sensitivity of
65.3% and specificity of 93.7% for the diagnosis of normal cognition.ConclusionsThe informant interview used at the BBBABSG has a high specificity and
sensitivity for the diagnosis of dementia as well as a high specificity for
the diagnosis of normal cognition.
The long, short and the new short Brazilian IQCODE versions can be useful as a screening tool for mild and moderate patients with dementia in Brazil. The IQCODE is not biased by schooling, and it seems to be an adequate instrument for samples with low levels of education.
Reaching a diagnosis may be difficult in the initial stages of dementia,
especially in low educated individuals, when informant reports may be
useful.ObjectivesTo compare the sensitivity and specificity of the IQCODE against cognitive
tests applied in clinical practice and to evaluate the possible cut-off
points in Brazil.MethodsIndividuals without dementia (CDR=0; N=5), with Mild Cognitive Impairment
(MCI) (CDR=0.5; N=15) and demented (CDR≥1; N=29) were evaluated using
the Short IQCODE, a 16-item questionnaire applied to an informant, and on
standard cognitive and functional scales. Diagnosis was reached by a
consensus team with expertise in dementia, according to DSM-IV criteria,
which was blind to the IQCODE results.ResultsIQCODE scores were positively correlated to the CDR (r=0.65, p<0.001) and
negatively correlated with years of schooling (r= –0.33, p=0.021). IQCODE
scores were positively correlated with CDR controlled by age and education
(r=0.61, p<0.001). Linear regression showed that age was associated with
the IQCODE (p=0.016) whereas education was not associated (p=0.078). IQCODE
means according to the CDR classification were: CDR 0–3.37; CDR 0.5–3.75;
CDR 1–4.32; CDR 2–4.61; CDR 3–5.00. The area under the ROC curve for
dementia vs. controls was 0.869 (p<0.001), MCI vs. controls, 0.821
(p<0.001); and according to the groups classified by the CDR was: CDR 0.5
vs. CDR 1=0.649 (p=0.089), CDR 1 vs. CDR 2=0.779 (p=0.009), and CDR 2 vs.
CDR 3=0.979 (p=0.023).ConclusionsThese preliminary findings suggest that the short IQCODE can be used for the
screening of MCI and dementia in Brazil.
Reduction of regional brain glucose metabolism (rBGM) measured by [18F]FDG-PET in
the posterior cingulate cortex (PCC) has been associated with a higher
conversion rate from mild cognitive impairment (MCI) to Alzheimer's disease
(AD). Magnetic Resonance Spectroscopy (MRS) is a potential biomarker that has
disclosed Naa/mI reductions within the PCC in both MCI and AD. Studies
investigating the relationships between the two modalities are scarce.ObjectiveTo evaluate differences and possible correlations between the findings of
rBGM and NAA/mI in the PCC of individuals with AD, MCI and of cognitively
normal volunteers.MethodsPatients diagnosed with AD (N=32) or MCI (N=27) and cognitively normal older
adults (CG, N=28), were submitted to [18F]FDG-PET and MRS to analyze the
PCC. The two methods were compared and possible correlations between the
modalities were investigated.ResultsThe AD group exhibited rBGM reduction in the PCC when compared to the CG but
not in the MCI group. MRS revealed lower NAA/mI values in the AD group
compared to the CG but not in the MCI group. A positive correlation between
rBGM and NAA/mI in the PCC was found. NAA/mI reduction in the PCC
differentiated AD patients from control subjects with an area under the ROC
curve of 0.70, while [18F]FDG-PET yielded a value of 0.93.ConclusionrBGM and Naa/mI in the PCC were positively correlated in patients with MCI
and AD. [18F]FDG-PET had greater accuracy than MRS for discriminating AD
patients from controls.
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