Impact of Executive Dysfunction on Verbal Memory Performance in Patients with Alzheimer's Disease

Abstract

It is currently accepted that there is a subset of patients diagnosed with Alzheimer's disease (AD) who show executive functioning (EF) impairments even in the earlier stages. These patients have been shown to present distinct psychiatric, behavioral, occupational, and even histopathological profiles. We assessed thirty patients with AD on two tasks of verbal memory (Logical Memory - LM, and the Rey Auditory-Verbal Learning Task - RAVLT), as well as classical tests of EF. AD patients were classified into either a spared EF (SEF) group if they showed impaired performance (z < -1.5 SD) in none or only one of the executive tests, or into an impaired EF (IEF) group if they showed impaired performance on two or more tasks of EF. Their performance was compared with fourteen healthy controls. SEF showed significantly more years of education than IEF, but the groups did not differ significantly on age, gender, mood symptoms, or performance on general screening tests or attentional tasks. With education as a covariate, both AD groups differed from controls on all measures of memory, but a significant difference was found between SEF and IEF patients only on the recognition phases of both logical memory (p < 0.01) and RAVLT (p = 0.02). Recognition scores significantly correlated with performance on executive tasks. Early AD patients who preserve their EF seem to have an advantage in their ability to recognize information that has been previously presented over patients with impaired EF. Such advantage seems to be strongly associated with executive performance.

A Two-Year Follow-Up of Cognitive Deficits and Brain Perfusion in Mild Cognitive Impairment and Mild Alzheimer's Disease

“…The poor recognition memory likely reflects a deficit in memory storage (vs., memory retrieval) and is characteristic of AD and other cortical dementias [56]. In AD patients, better performance on executive function tests is associated with better verbal recognition memory [57]. So, it may be the case that in the prodromal stages of AD (relatively) normal executive functions may be compensating for (mildly) affected verbal memory, but when verbal memory recognition performance get worse, this indicates that the patients are advancing closer to AD dementia.…”

The SEA (Social Cognition and Emotional Assessment): A clinical neuropsychological tool for early diagnosis of frontal variant of frontotemporal lobar degeneration.

“…As for the cognitive profile, the AD and FTD groups were matched only for MMSE and FAB. However, it should be noted that neither group differed on span and verbal fluency assessments, which are executive tests that are very sensitive for detecting early impairment in AD (Gleichgerrcht, Torralva, Martinez, Roca, & Manes, 2011;Nestor, Scheltens, & Hodges, 2004;Stopford, Thompson, Neary, Richardson, & Snowden, 2010).…”

Executive functioning and risk for Alzheimer’s disease in the cognitively intact: Family history predicts Wisconsin Card Sorting Test performance.

“…Deficits in this domain are, in fact, among the first nonmemory impairments to emerge with AD onset (Amieva, Phillips, Della Sala, & Henry, 2004b). Moreover, these executive deficits may be related to, or even underlie, certain aspects of memory decline (Baudic et al, 2006;Gleichgerrcht et al, 2011;Hasher et al, 2007). Further research elucidating the role of EF in risk for AD is, therefore, necessary.…”

“…EF deficits among individuals who have been diagnosed with AD are now widely recognized (Espinosa et al, 2009;Stokholm, Vogel, Gade, & Waldemar, 2006;Takeda et al, 2010). More important, it has been suggested that memory deficits in AD are related to executive impairments (Baudic et al, 2006;Gleichgerrcht, Torralva, Martinez, Roca, & Manes, 2011;Hasher, Lustig, & Zacks, 2007) and that EF deficits are associated with decreased functioning in activities of daily living, which represent an essential criterion in the diagnosis of AD (Jefferson, Paul, Ozonoff, & Cohen, 2006;Martyr & Clare, 2012). Research indicating that AD pathophysiology begins years, and possibly even decades, before the onset of clinical symptoms has spurred the exploration of preclinical markers of future cognitive decline (Sperling et al, 2011).…”