Keywords

• Everyday;
• Self-report;
• Memory;
• Children;
• Epilepsy;
• Attention;
• Mood;
• Emotion;
• Parent report

1. Introduction

Memory deficits are well documented among children with epilepsy. Using standardized objective measures, researchers have demonstrated difficulties in a range of areas, including working memory, verbal memory, and nonverbal or spatial memory [1], [2], [3], [4] and [5]. The impact of these deficits on everyday functioning is not fully understood.

Everyday memory refers to the day-to-day application of recognition, recall, and prospective memory. An effective everyday memory system is integral to successful negotiation of events occurring in normal, everyday contexts. However, some amount of error within the system is typically accepted. Most children and adults can relate to occasional forgetting that occurs in everyday contexts; for example, forgetting a friend's phone number or forgetting to bring a lunch to school or work.

In practice, we distinguish everyday memory from functions measured using standard neuropsychological tasks, typically employed in the assessment of patient populations. Standard objective memory measures are useful for establishing performance relative to members of the healthy population, and may facilitate the detection of subtle domain-specific strengths or weaknesses within an individual. However, since clinical/research settings are necessarily strictly controlled, and tests are typically novel and focused in breadth, standard objective memory measures may not accurately characterize typical, everyday experience. In studying everyday memory, researchers hope to gain better understanding of how performance on standard tests applies to nonlaboratory settings (i.e., an issue of ecological validity), and to establish factors contributing to an individual's perception of his or her own memory abilities.

Although failings in everyday memory occur among all individuals, seldom do otherwise healthy people complain of poor memory that has a negative and significant impact on quality of life. As McMillan [6] observed, when healthy individuals were asked about their everyday memory function, they collectively rated their abilities as categorically “above average.” In contrast, memory complaints are common in individuals with neurological compromise, prompting studies of everyday memory among people with dementias (for a review, see [7]), HIV/AIDS (e.g., [8]), and epilepsy (e.g., [9]). The higher incidence of everyday memory problems among people with epilepsy than among healthy controls has been well established (e.g., [9], [10], [11], [12] and [13]).

In adults with epilepsy, findings regarding the relationship between objective measures of memory and self-ratings of memory are inconsistent; in children with epilepsy, this relationship has not been explored. Compared with all other cognitive deficits, memory complaints present as the most common problem among individuals with epilepsy, causing substantial distress [9] and [11]. However, it is unclear whether deficits in specific memory processes, as measured by standard neuropsychological testing, underlie these complaints. McGlone [14] tested adults with temporal lobe epilepsy using a self-report measure of everyday memory and standard neuropsychological measures of memory, and found that everyday memory significantly correlated with memory performance on the standard measures. However, the shared variance was reported as “generally very low, i.e., <16%” [14, p. 535]. Giovagnoli et al. [12] observed a similar pattern of moderate correlations between everyday memory scores and performance on standard neuropsychological measures. Through regression analyses, Giovagnoli et al. [12] found that measures of anxiety and depression better predicted everyday memory than did performance on standardized memory measures. In a slightly different design, Elixhauser et al. [15] assessed everyday memory in people with epilepsy using a standardized objective measure, the Rivermead Behavioural Memory Test (RBMT) [16], and assessed perceived cognitive function using cognitive domain scores (comprising memory, attention/concentration, and language subscales) from the Quality of Life in Epilepsy questionnaire (QOLIE-89) [17]. Although the memory subscale of the QOLIE-89 significantly correlated (r=0.18, P<0.05) with RBMT performance, this correlation was not greater than either attention/concentration (r=0.18, P<0.05) or language (r=0.24, P<0.01) subscale correlations with RBMT performance. A regression analysis revealed that only 2% of variance in QOLIE-89 cognitive domain scores was accounted for by RBMT performance, while 56% of variance in QOLIE-89 cognitive domain scores was accounted for by mood state alone.

The association between everyday memory and standard neuropsychological measures of memory has been studied to a lesser extent in children. In one study, Smith and Vriezen [18] administered a self-report measure of everyday memory to the parents of children with epilepsy and to parents of a healthy child cohort, and found that parents' ratings of child everyday memory performance were not significantly correlated with children's performance on standard measures of verbal and nonverbal memory.

Across a variety of populations with neurological disorders/compromise, mood and some age-related factors appear to best predict everyday memory estimates. Elevated levels of anxiety and/or depression are associated with increases in everyday memory deficits in adults with epilepsy [11], [12] and [15] and adults with HIV infection [8]. In adults with epilepsy, age and duration of seizure disorder may also predict everyday memory complaints [9] and [19]. Furthermore, researchers have shown that age interacts with mood state to predict increases in everyday memory deficits in adults with early-stage dementias [7]. A recent study suggests that anxiety and depressive symptomology may be associated with poorer everyday memory performance in children/adolescents with posttraumatic stress disorder [20]. No data have been published on mood and everyday memory in children with epilepsy. The exploration of predictors of everyday memory in child populations is in its infancy.

For a number of reasons, we cannot assume that children with epilepsy have memory systems equivalent to those of adults with epilepsy. Developmental processes place the child and adult at different stages with respect to memory capacity and everyday memory demands. Additionally, neurodevelopmental processes may allow children's brains to accommodate insults (responsible for and maintained by epileptogenic discharges) differently than the adult brain (an issue of plasticity) [21], [22] and [23]. Lastly, seizures over decades may have a cumulative effect on the brain of an adult with epilepsy, whereas the brain of a child with epilepsy is more likely to have experienced seizures for a shorter duration.

In this study, we investigate whether standard neuropsychological measures and/or mood/emotional state predict everyday memory in children with medically intractable epilepsy. Because our study is exploratory, we include measures of attention and global cognitive functioning in addition to objective memory measures; an inclusive approach permits detection of subtle domain-specific relationships, should any exist. Through inclusion of mood/emotional state variables, we are able to determine whether mood predicts everyday memory in children with epilepsy, as found in adult populations.