Combining functional scales and cognitive tests in screening for mild cognitive impairment at a university-based memory clinic in Brazil Combinação de escalas funcionais e testes cognitivos para rastreio de comprometimento cognitivo leve em ambulatório universitário de memória no Brasil

Objective: To determine the diagnostic accuracy of the Mini-Mental State Examination combined to the Informant Questionnaire on Cognitive Decline in the Elderly for the identification of mild cognitive impairment. Method: 191 elderly subjects were assessed with the Mini-Mental State Examination, and their informants were assessed with the Informant Questionnaire on Cognitive Decline in the Elderly. Subjects were divided into three groups according to their cognitive state (controls: n = 67, mild cognitive impairment: n = 65 and dementia: n = 59), which was ascertained by clinical and neuropsychological evaluation. The diagnostic accuracy of each test in the discrimination of diagnostic groups (mild cognitive impairment vs. controls, mild cognitive impairment vs. dementia and dementia vs. controls) was examined with the aid of ROC curves. We additionally verified if the combination of both tests would increase diagnostic accuracy for mild cognitive impairment and control identification. Results: The combination of the Mini-Mental State Examination and the Informant Questionnaire on Cognitive Decline in the Elderly scores did not increase the Mini-Mental State Examination diagnostic accuracy in the identification of patients with mild cognitive impairment. Conclusions: The present data do not warrant the combination of the Mini-Mental State Examination and the Informant Questionnaire on Cognitive Decline in the Elderly as a sufficient diagnostic tool in the diagnostic screening for mild cognitive impairment. Descriptors: Geriatric psychiatry; Dementia; Scales; Neuropsychological tests; Diagnosis Resumo Objetivo: Avaliar a acurácia diagnóstica do Mini-Exame do Estado Mental combinado ao Questionário do Informante sobre Declínio Cognitivo na identificação de casos de comprometimento cognitivo leve. Método: 191 indivíduos idosos foram avaliados com o Mini-Exame do Estado Mental e seus informantes com o Questionário do Informante sobre Declínio Cognitivo. Os indivíduos foram divididos em três grupos de acordo com o estado cognitivo (controles: n = 67; comprometimento cognitivo leve: n = 65; demência: n = 59), segundo avaliação clínica e neuropsicológica. Pela análise de curvas ROC, avaliamos a acurácia diagnóstica de cada teste para diferenciar os grupos diagnósticos (comprometimento cognitivo leve vs. controles; comprometimento cognitivo leve vs. demência; demência vs. controles). Adicionalmente, verificamos se a combinação dos dois testes fortalece a acurácia diagnóstica para a separação dos casos de comprometimento cognitivo leve dos controles normais. Resultados: A análise combinada do Questionário do Informante sobre Declínio Cognitivo e Mini-Exame do Estado Mental não aumentou a acurácia diagnóstica do Mini-Exame do Estado Mental em predizer a ocorrência de comprometimento cognitivo leve. Conclusões: Os dados deste estudo não sustentam a utilidade clínica da combinação dos escores do Mini-Exame do Estado Mental e do Questionário do Informante sobre Declínio Cognitivo no rastreio diagnóstico do comprometimento cognitivo leve. Descritores: Psicogeriatria; Demência; Escalas; Testes neuropsicólogicos; Diagnóstico Izabella Dutra de Abreu,1 Paula Villela Nunes,1 Breno Satler Diniz,1 Orestes Vicente Forlenza1 Correspondence Orestes Vicente Forlenza Laboratory of Neuroscience (LIM 27), Department and Institute of Psychiatry BRIEF REPORT 347 Combining functional and cognitive scales Introduction The recognition of symptoms indicative of the risk of dementia in older adults is important, given the prospect of the development of drugs with disease-modifying properties, which would be more efficacious if started in the early stages of the disease.1 At present, the best attempt to characterize such individuals is the definition of mild cognitive impairment (MCI), which refers to subjects with or without subjective cognitive complaints, objective impairment in cognitive assessment (provided scores are corrected for relation to age and educational level), minimal or no evidence of impairment in the performance of daily activities, and not demented.2 In most studies, the neuropsychological evaluation remains as the gold standard for diagnosis of MCI. Nonetheless, a comprehensive neuropsychological evaluation is costly, time-consuming, and demands well-trained professionals, thus hindering its widespread use in primary care. Therefore, MCI patients may not be easily recognized in primary clinical settings, delaying the proper identification of subjects with an increased risk of dementia. Cognitive screening tests can be divided into two broad categories: tests that objectively assess the cognitive performance (e.g. the MiniMental State Examination MMSE, the Clock Drawing Test), and informant-based questionnaires (e.g. the Informant Questionnaire of Cognitive Decline in the Elderly IQCODE). The MMSE is the most widely used cognitive screening test and has been validated in several languages and cultures for the diagnostic screening of dementia. The IQCODE is an informant-based questionnaire that compares the patient’s present ability to perform several activities of the daily living, and tasks that demand intact recent episodic memory and intellectual abilities over a continuum of 10 years. It is composed of 26 items individually scored from 1-“much better” to 5 -“much worse”. Intermediate scores of 2 and 4 indicate slightly better or worse, respectively; score of 3 indicates no significant changes in comparison to 10 years ago. The final score is given by the sum of the 26-item scores divided by 26, and it ranges from 1 to 5, with higher scores indicating worse functional status.3 The IQCODE is supposedly not unaffected by education, premorbid intellectual ability, or by proficiency in the culture’s dominant language.4 On the other hand, because the IQCODE relies on the information provided by a caregiver or a close relative of the patient, scores may be biased by the informant’s cognitive and emotional state (such as depression and anxiety) or personality traits, and by the other factors affecting the relationship between the informant and the patient. These factors can both minimize or maximize the actual deficits. The IQCODE has been shown to have a good sensitivity and specificity to identify cases of dementia,5 but very few studies have so far addressed the diagnostic properties of the IQCODE in the diagnostic screening of MCI. Previous reports showed that the association of cognitive screening tests improves the potential of a single test to differentiate individuals with Alzheimer’s disease (AD) from unimpaired elderly patients.6 Therefore, the aim of this work is to ascertain whether the association of two widely used cognitive screening tests, i.e. the MMSE and the IQCODE, is more accurate than each test alone to discriminate cognitively unimpaired elderly subjects from patients with MCI and AD. We hypothesize that the association of these two screening instruments have a higher accuracy in the identification of cognitive impairment than either test alone. Method 1. Patients One hundred and ninety-one elderly patients (67 controls, 65 MCI, and 59 AD) were assessed at a university-based memory clinic from December 2001 to May 2006. Age and educational level for patients and controls are presented in Table 1. Patients were recruited from community sources for the assessment of suspected cognitive decline in São Paulo, Brazil. This study was approved by the Ethical Committee of Hospital das Clínicas University of São Paulo (protocol number: 1032/07), and was performed in accordance with the Helsinki Declaration. 2. Clinical assessment The cognitive assessment and the diagnostic procedures in this cohort are described in details in previously published studies.7 In brief, patients were examined by clinicians specialized in the evaluation of cognitive disorders. The clinical assessment included the Cambridge Mental Disorders of the Elderly Examination (CAMDEX) interview, which yields the Cambridge Cognitive Examination (CAMCOG) and the MMSE scores. The IQCODE was further administered to a close relative or caregiver of each subject. The 21-item Hamilton Depression Scale8 was administered to rule out depressive symptoms. Evidence of functional decline was suggested by the informant’s or the patient’s report of difficulties performing activities of daily living. The neuropsychological evaluation was carried out as the gold standard for the diagnosis of MCI and AD as described in previous studies.9 It included the Rivermead Behavioral Memory Test (RBMT), the Fuld ObjectMemory Evaluation (FOME), the Trail Making Test (TMT) A and B, the Short Cognitive Test (SKT) and the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Vocabulary and Block Design tests. The neuropsychologists responsible for the assessments were blinded to the MMSE and IQCODE scores when the tests were administered. For the sake of conciseness, only the scores for the IQCODE and the MMSE will be reported in this paper (Table 1). 3. Diagnosis Clinical diagnoses were reached by consensus at expert multi-disciplinary meetings, taking into account clinical, neuropsychological, laboratorial, and neuroimaging data. The MMSE and IQCODE scores per se were not taken into account for establishing the clinical diagnosis. Dementia was diagnosed according to the DSM-IV criteria.10 In this study, we included patients that fulfilled the diagnostic criteria for AD according to the NINCDSADRDA11 or for MCI according to Petersen et al.,12 in addition to cognitively unimpaired age-matched controls. Patients with evidence of depressive or anxiety disorders were excluded from the study, as well as patients with other dementia syndromes, such as vascular dementia and other neurodegenerative diseases, diagnosed according to the currently accepted diagnostic criteria.13-15 4. Statistical analysis Non-parametric statistics were performed to assess median differences between the diagnostic groups (Kruskall Wallis test), while analysis of variance (ANOVA) was performed to control for the variable age. Backward stepwise logistic regression analysis was performed to assess whether the two tests used together provided any additional information for predicting MCI over that given by either test used alone. Receiving Operating Characteristics (ROC) analyses were performed for each test comparing the diagnostic group in a two-by-two fashion. The accuracy of each test, and of their association, is represented by the area under the curve (AUC). In addition, cutoff values and the respective sensitivity and specificity values were drawn by ROC analyses. ROC curves were also constructed for the combination of the tests for MCI accuracy according to the Mackinnon and Mulligan’s weighted sum rule.16