DIAGNOSTIC ACCURACY OF THE ETIOLOGICAL DIAGNOSIS OF NEWLY MANIFESTED COGNITIVE IMPAIRMENT IN GERIATRIC INPATIENTS INCLUDING CEREBRAL MRI AND FDG-PET

Abstract

The cause of cognitive impairment in acutely hospitalized geriatric patients is often unclear. The diagnostic process is challenging but important in order to effectively treat potentially life threatening etiologies or identify underlying neurodegenerative disease. This study evaluated the diagnostic accuracy of the etiological diagnosis including structural and metabolic neuroimaging in newly manifested cognitive impairment in elderly geriatric patients hospitalized due to acute or subacute admission indications (WHO Trials Registry DRKS00005041). Structural brain MRI for assessment of cerebrovascular pathology and brain atrophy as well as brain FDG PET for detection of characteristic patterns of neuronal dysfunction were completed in 88 (58 females, 81.4±5.4 years) of 103 enrolled patients. The main inclusion criterion was ‘uncertain case’, i.e., the cause of cognitive impairment was sufficiently unclear so that additional diagnostic procedures including detailed neuropsychological testing and neuroimaging appeared useful for each individual participant. The most probable etiological diagnosis was made by an interdisciplinary academic expert team integrating all available data (clinical, laboratory, neuropsychological, and neuroimaging). The following etiological categories were used: Alzheimer's disease (AD), cerebrovascular disease (CVD), mixed disease (MD=AD+CVD), other neurodegenerative disease than AD (otherDeg), and non-neurodegenerative etiology (otherNonDeg, e.g. depression). Clinical follow-up including detailed neuropsychological testing after 16±3 months could be performed in 63 patients (72%, 43 females, 81.0±5.5 years at baseline) in their home environment. Follow-up data was not available because of rejection by the patient (10%), death (11%), or still outstanding follow-up visit (7%). The etiological diagnosis at follow-up was used as gold standard to evaluate the accuracy of the etiological diagnosis at baseline. Baseline etiological diagnosis was confirmed by the follow-up in 53 patients (84.1%) The following changes occurred in the remaining 10 patients: MD to CVD (n=3), otherNonDeg to AD (3), AD to otherDeg (1), CVD to otherDeg (1), otherDeg to AD (1), and otherNonDeg to CVD (1, intermediate stroke). The duration of follow-up did not differ between confirmed and adjusted etiological diagnosis (p = 0.693). Integration of structural MRI and FDG PET into the diagnostic process allows the etiological diagnosis of de novo cognitive impairment in acutely hospitalized geriatric patients with similar accuracy as in less ‘difficult‘ settings.