Evoked Potentials and Neuropsychological Tests Validate Positron Emission Topography (PET) Brain Metabolism in Cognitively Impaired Patients

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From: PLoS ONE(Vol. 8, Issue 3)
Publisher: Public Library of Science
Document Type: Article
Length: 6,251 words
Lexile Measure: 1510L

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Author(s): Eric R. Braverman 1 , 2 , * , Kenneth Blum 1 , 2 , 3 , Uma J. Damle 1 , Mallory Kerner 1 , Kristina Dushaj 1 , Marlene Oscar-Berman 4

Introduction

Dementia is the sixth leading cause of death in the United States, increasing in incidence and prevalence as the "baby boomer" generation ages along with longer life expectancies [1]. With the economic burden of dementia consistently rising [2], early identification of cognitive decline in primary care settings is imperative [3]. Decades of research involving brain electrophysiology have shown that delayed latency in the P300 brain wave (the positive spike in an EEG wave 300 ms after a stimulus) and a lower amplitude in the voltage of the P300 wave, occur in both normal aging, and even more so, in dementia [4]. However, little is known about the relation of electrophysiological parameters (P300), HM of the brain, and MCI/Alzheimer's disease (AD) markers such as tau proteins, C-reactive protein, and hippocampal atrophy [5], [6], [7]. If a patient diagnosed with clinical MCI is positive for these markers, prodromal AD should be considered. Magnetic Resonance Imaging or Angiogram (MRI, MRA) and PET are useful techniques that permit us to track abnormalities that may be markers of MCI or AD [8]-[11]. Both P300 and PET can detect early functional changes in MCI before anatomical damage becomes evident on MRI/MRA or neuropsychological profiles. There is also a paucity of information linking scores on the Mini-Mental State Examination (MMSE) [12] and brain HM in early cognitive decline [13], [14]. Finally, there are no studies to our knowledge that have evaluated the validation ability of three common assessment tools for revealing brain HM: Central Nervous System Vital Signs Memory Test (CNSM); Test of Variables of Attention (TOVA); and Wechsler Memory Scale-III (WMS). Our hypothesis is that evoked potentials and neuropsychological tests can validate PET brain metabolism and MCI, or early stages of Alzheimer's disease [15]. Therefore, the current retrospective study systematically examined the sensitivity and specificity of using P300, TOVA, and memory tests (WMS, CNSM, and MMSE) as early indicators of HM as measured by PET, in a cohort of patients with amnestic and non-amnestic cognitive impairments presenting to a large medical practice [16].

Methods

Participants

Of the more than 9,000 outpatients who visited a neuropsychiatric private practice group in Manhattan (1998-2009), 662 receiving a fluorodeoxyglucose (FDG) PET scan expressed interest in enrollment in the study, and signed written informed consent forms. The study sample was further refined by selecting patients (n = 240) with data available from P300 [17] visual and auditory evoked potentials, TOVA, WMS, MMSE, and CNSM. Subjects enrolled in the study performed testing on arrival and were advised not to take medications 24 hours prior to testing and were asked to refrain from caffeine, nicotine, and alcohol as well. Subjects did not undergo any Magnetic Resonance (e.g., MRI, MRA). Subjects indicated if they had depressive symptoms (n = 124) prior to the study and were evaluated for depression...

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Gale Document Number: GALE|A478193118