Declarative Memory in Early Parkinsons Disease: Serial Position Learning Effects

Abstract

This study tested the question of whether executive failure associated with frontal lobe deficit is associated with, and therefore, may influence declarative memory dysfunction in Parkinson's disease (PD). A variety of memory and 'frontal sensitive' tasks were used. The 'frontal lobe dysfunction' hypothesis was tested in part, by examining the serial position effects (SPE) of word list learning across five successive trials. The relationship between memory and 'frontal sensitive' task scores was tested also. A total of 39 PD patients early in the course of the disease and 31 matched controls were included in the study. The PD subjects showed mild memory deficits in comparison to the healthy control group. In the face of any hypothesized selective 'dysexecutive' syndrome in PD group, the latter groups learning strategy across five trials did not differ from that of the control group. Also, the expected interrelation between memory and 'frontal sensitive' scores was not obtained. Therefore, the hypothesis that frontal dysfunction alone may account for memory impairments in PD is not fully supported.

Source memory and frontal functioning in Parkinson’s disease

“…Given this connectivity between the striatum and the DLPFC, it is not surprising that PD-related dysfunction in the striatum can lead to impairments in those cognitive processes dependent on the DLPFC, namely, executive functioning (Mega et al, 1994; Rinne et al, 2000). Studies have found a range of executive functioning deficits in individuals with PD, including working memory (Farina et al, 2000; Owen et al, 1992; Owen et al, 1995; Postle et al, 1997), planning and problem-solving ability (Culbertson et al, 2004; Hanes et al, 1996; Lewis et al, 2003;), verbal fluency (Azuma et al, 2003; Green et al, 2002; Gurd, 1995; Hanes et al, 1996; Stefanova et al, 2001), and set-shifting (Bondi et al, 1993; Dirksen et al, 2006; Farina et al, 2000; Green et al, 2002; Hayes et al, 1998; Lange et al, 1992; Owen et al, 1992; Stamenovic et al, 2004), although findings of frontal deficits have not been entirely consistent (Farina et al, 2000; Gabrieli et al, 1996; Levin et al, 1989; Rogers et al, 1998), possibly due to heterogeneity in samples. It has been suggested that these executive functioning deficits are direct effects of dopamine dysregulation, and neuroimaging studies using both PD and nonclinical populations have linked markers of dopamine and functional activation in both the striatum and the prefrontal cortex to performance on executive functioning tasks (Backman et al, 2000; Brück et al, 2001; Cropley et al, 2006; Lewis et al, 2003; Marie et al, 1999; Rinne et al, 2000; Sawamoto et al, 2008; van Beilen et al, 2008; Volkow et al, 1998).…”

Neuropsychological Deficits in Initial Parkinson’s Disease

“…We have noticed that they learn new information but slower and with lower performance level than the controls, that means, they have fewer scores in memory tests, with and without clues, and in the recognition test. Probably, as other authors have found (Stefanova et al, 2001;Weintraub et al, 2004;Verbaan et al, 2007;Zizak et al, 2005), this deficit is due to inefficient use of strategies during the encoding and the storage, which involves a lower recovery because of the inefficiency in the planning and the organization of information. Other studies have found that executive deficits in patients with early PD such as lack of planning, the use of strategies and the phenomenon of interference, together with working memory deficits (as found in test and subtest Letters and Numbers of the WAIS (Wechsler Adults Intelligence Scale), could be the main reason of some of the alterations seen in short term and long term memory, in verbal and visual modalities (Cooper et al, 1991;Muñiz Casado & Rodríguez Fernández, 2007;Pillon et al, 1998)).…”

Cognitive Impairment in Parkinson’s Disease: Historical Review, Past, and Present

“…However, patients can perform poorly, compared to controls, even in recognition memory tasks [6]. Using tasks that allowed a more precise examination of different memory components (e.g., the Auditory Verbal Learning Test and the California Verbal Learning Test), some authors reported deficits in learning and spontaneous recall, without alteration in recognition [27,37,46]. However, this impairment pattern was not confirmed by other authors who found alterations in cued recall and recognition [47][48][49][50].…”

“…The results obtained are diverse, probably as a consequence of the wide range of instruments used (Visual Retention Test, Visual Paired Associates, Face Memory Test, Complex Figure Test, etc.) [27,45,46,52]. Visuospatial learning has been evaluated by Pillon et al [53,54] who found that PD patients present an altered execution.…”