A test that assesses schizophrenia patients’ ability to do grocery shopping is a good measure of cognitve processes such as planning, rule acquisition, and inhibition, collectively known as executive function, in a natural environment, according to researchers.
The Test of Grocery Shopping Skills (TOGSS) showed close correlation with eight measures of executive function, study co-author Elizabeth Zayat (Rockhurst University, Kansas City, Missouri, USA) and colleagues reported in the journal Psychiatry Research.
“Assessments in natural settings provide an opportunity to see an individual’s ability to respond in a dynamic, novel, and unpredictable environment. While measures that mimic real-world situations have been shown to be capable of assessing executive function, measures that occur in a real-world environment may allow us to better discern specific executive functions,” they said.
Executive dysfunction is one of the most ubiquitous features of schizophrenia and is closely related to functional outcomes, such as employment.
The TOGSS requires participants to accurately select the correct item, correct size, and lowest price for 10 target items on a grocery list. Efficiency is calculated by determining the number of aisles or sections of the store that the participant enters, and subtracting from this the actual number of aisles required to most efficiently find the 10 items on the list.
For the current study, 47 individuals with schizophrenia and 33 with schizoaffective disorder completed the TOGSS after recruitment from mental health centers in the Kansas City area.
They also underwent a battery of eight clinical executive function tests including the Trail Making Test (TMT), Wisconsin Card Sorting Task (WCST), Letter Number Sequencing Ordering Test of Working Memory (MO), and Digit Span Backward (DSB).
A multivariate statistical technique, called canonical correlation analysis (CCA), was applied to explore the relationship between the two sets of variables.
This revealed a significant correlation such that 30 percent of the variance in the executive function and grocery shopping measures was shared.
Specifically, shopping efficiency correlated with the WCST perseverative errors, WCST trials to category 1, WCST total correct, and LNS measures; while shopping accuracy correlated with MO, DSB, and LNS measures.
The researchers say the study findings support the continued exploration of the TOGSS. However, they add that the evidence for specific relationships between executive function domains and TOGSS is moderate and requires replication.