HPA axis function predicts development of working memory in boys with FXS

Abstract

The present study examines verbal working memory over time in boys with fragile X syndrome (FXS) compared to nonverbal mental-age (NVMA) matched, typically developing (TD) boys. Concomitantly, the relationship between cortisol—a physiological marker for stress—and verbal working memory performance over time is examined to understand the role of physiological mechanisms in cognitive development in FXS. Participants were assessed between one and three times over a 2-year time frame using two verbal working memory tests that differ in complexity: memory for words and auditory working memory with salivary cortisol collected at the beginning and end of each assessment. Multilevel modeling results indicate specific deficits over time on the memory for words task in boys with FXS compared to TD controls that is exacerbated by elevated baseline cortisol. Similar increasing rates of growth over time were observed for boys with FXS and TD controls on the more complex auditory working memory task, but only boys with FXS displayed an association of increased baseline cortisol and lower performance. This study highlights the benefit of investigations of how dynamic biological and cognitive factors interact and influence cognitive development over time.

Measuring Cortisol in the Classroom with School-Aged Children—A Systematic Review and Recommendations

“…Nine of the papers that emerged from the literature search used salivary cortisol as a measure of acute stress [ 1 , 2 , 4 , 5 , 8 , 9 , 37 , 38 , 41 ].…”

“…The remainder of the studies that will be presented in this section have been conducted with different clinical groups. Scherr et al [ 41 ] compared boys with Fragile X Syndrome (FXS) and typically developing (TD) ( N =105), using a verbal working memory assessment task. Boys were non-verbal mental age-matched and a subgroup of the total number of participants provided saliva samples ( N = 80; N = 31 FXS; N = 49 TD).…”

“…The research shown here has mostly used cotton Salivettes [ 2 , 4 , 5 , 8 , 9 , 37 , 38 , 41 ] to collect the saliva samples, with one study using both passive drool and Salivettes [ 1 ]. However, when discussing the protocol of collection, again, variation across studies becomes apparent.…”

“…However, when discussing the protocol of collection, again, variation across studies becomes apparent. Scherr et al [ 41 ] collected saliva samples 15 min before the assessment as a baseline measure (9 a.m.) and straight after the assessment as a measure of the effect of the assessment (12 p.m.), where 95% of participants took part in school. The children were encouraged to be well rested and if unwell, parents were asked to reschedule the assessment, although this would have been difficult to ensure.…”

“…Palma et al [ 1 ] stated that three participants were excluded due to missing data, although it is unclear whether the missing data was cortisol samples, whereas Gustafsson et al [ 9 ] indicated that 240 of 336 reference group children (participants used from another study conducted by the same research team) provided the acute measure of cortisol and one child in the OCD group did not provide both saliva samples. Similarly, research by Scherr et al [ 41 ] has established that some samples were missing at random due to non-compliance, excessive artefacts or evaporation of samples, but it is not clear how many samples were missing. However, they carried out checks and confirmed that participants were still matched according to mental age.…”