Article summary with Differential effects of everyday stress on the episodic memory test performances of young, mid-life, and older adults by VonDras a.o. - 2005

What is the aim of the present study? 

Stress can be defined as any condition that perturbs physiological and psychological homeostasis and is reflected in behaviors varying from mild memory impairment to dissociation and flashbacks. Much research has been conducted on stress, with many studies suggesting that stress has a negative impact on neurological structures involved in learning and memory. In addition, stress has been found to be a factor that may accelerate age-related cognitive decline. Yet, although there is a lot of research suggesting the negative impact stress has on neurological structures and cognition, much less psychometric investigation has been conducted on stress encountered in daily life and its effects on the memory tests currently used to discern mild cognitive impairment. To fill this gap, the current study aimed to investigate the impact of everyday stress on the episodic memory test performances of young, mid-life, and older adults. Everyday stress is defined as the appraisal of hassles and irritations of daily life, and as an accumulation of challenging events. Episodic memory is the memory of every day events (for example: times, location, associated emotions and other contextual information) that can be explicitly stated or conjured. It is the collection of past personal experiences that occurred at a particular time and place. 

How is the study conducted?

The sample consisted of 98 adults that were recruited via media advertisements. Individuals with neurological diseases (for example Parkinson's disease), psychiatric disorders (for example alcohol abuse or major depression), and use of medications producing sedative effects, were excluded. The sample was predominantly white with 96 Caucasian adults. The female to male ratio was 69:29. Participants ranged in age from 19 to 89 years with a mean of 42.10 years. 

All measures were individually administered. The study included measures that were well known for their ease of administration and clinical efficacy in discerning cognitive function. In total, each study session took approximately 45 minutes. A brief battery of memory tests was used, including the: (a) Logical Memory Scale (LM) and Verbal Paired Associates of the Wechsler Memory Scale; (b) the Digit Symbol Substitution of the Wechsler Adult Intelligence Scale; and (c) the cued-recall Digit Symbol Incidental Learning test. After administration of these memory tests, participants were asked to complete a self-report questionnaire that contained two measures of stress: (a) the Perceived Stress Scale (PSS), and; (b) the Elders Life Stress Inventory (ELSI). 

The Logical Memory Scale (LM) assesses episodic memory for orally presented information. It involves immediate (LM-I) and delayed (LM-II) recall of two prose passages that are read to the person. A total score of both the immediate and delayed conditions are obtained by averaging the recall for both prose passages at each respective time of recall. 

Data analysis was conducted in SPSS. Correlational and hierarchical multiple regression correlational techniques were used to study the association between variables and the unique influence of everyday stress on episodic memory performance. 

What are the results of the study? 

First and foremost, as expected, differential associations of everyday stress indexes (PSS and ELSI) with memory tests were observed. That is, PSS and ELSI were fund to be significantly correlated with the recall of the prose passages (LM-I and LM-II), but not with other memory tasks.

Second, age and education were found to be significantly correlation with memory measures. A poorer performance on all memory tests was found with advanced age. A enhanced performance on recall of prose passages was found for participants with higher educational levels.

In sum, the results of this study suggest that everyday hassles and irritations as well as the accumulation of challenging life events may exacerbate age-related decline on episodic memory tests that require greater executive resources and more integrated and elaborative processing. 

Lastly, a note for future research: To allow for more sensitive interpretation of episodic memory tests that are commonly used to discern mild cognitive impairment, the authors suggest to consider individual differences in everyday stress.