Memory impairment, executive dysfunction, and intellectual decline in preclinical Alzheimer's disease

Department of Neurology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York 10467, USA.
Journal of the International Neuropsychological Society (Impact Factor: 3.01). 04/2008; 14(2):266-78. DOI: 10.1017/S1355617708080302
Source: PubMed

ABSTRACT In the Baltimore Longitudinal Study of Aging (BLSA), we examined the temporal unfolding of declining performance on tests of episodic memory (Free Recall on the Free and Cued Selective Reminding Test), executive function (Category Fluency, Letter Fluency, and Trails), and Verbal Intelligence (Nelson, 1982; American Version of the Nelson Adult Reading Test [AMNART]) before the diagnosis of dementia in 92 subjects with incident Alzheimer's disease (AD) followed for up to 15 years before diagnosis. To examine the preclinical onset of cognitive decline, we aligned subjects at the time of initial AD diagnosis and examined the cognitive course preceding diagnosis. We found that declines in performance on tests of episodic memory accelerated 7 years before diagnosis. Declining performance on tests of executive function accelerated 2-3 years before diagnosis, and verbal intelligence declined in close proximity to diagnosis. This cognitive profile is compatible with pathologic data suggesting that structures which mediate memory are affected earlier than frontal structures during the preclinical onset of AD. It also supports the view that VIQ as estimated by the AMNART does not decline during the preclinical onset of AD.

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    ABSTRACT: Alzheimer's disease (AD) is the most common form of dementia. Neuropsychological assessment of individuals with AD primarily focuses on tests of cortical functioning. However, in clinical practice, the underlying pathologies of dementia are unknown, and a focus on cortical functioning may neglect other domains of cognition, including subcortical and executive functioning. The current study aimed to improve the diagnostic discrimination ability of the Consortium to Establish a Registry for Alzheimer's Disease - Neuropsychological Assessment Battery (CERAD-NAB) by adding three tests of executive functioning and mental speed (Trail Making Tests A and B, S-Words).
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    ABSTRACT: This paper sheds light on a hidden epidemic that is the precursor to widespread disease: mild-moderate cognitive impairment (MCI). Although it is commonly considered to be a consequence of the normal aging process, cognitive decline frequently begins as early as 30, starting with a slowing of processing speed that then affects memory and attention, and leads to numerous diseases including obesity and depression. Decades pass in this impaired state before the patient experiences the first clinical symptoms of dementia. The Brain Evaluation and Assessment Method (BEAM) for diagnosing cognitive impairment will be introduced, along with a new paradigm for "dementia" and how it develops. Potential methods for diagnosing, preventing, and reversing cognitive decline and the myriad diseases associated with it will be discussed.

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