In the present study, we examined the association between self-reported fatigue and verbal fluency in a sample of healthy adults. Given the co-occurrence of anxiety and depressive symptoms with fatigue, we examined whether these affective dimensions would modify this association.
Fifty-nine cognitively normal adults took part in the study. Fatigue symptoms were assessed using the Fatigue Severity Scale (FSS), depressive symptomatology with the Center for Epidemiologic Studies Depression Scale (CES-D), and situational anxiety using the state subscale of the State-Trait Anxiety Inventory (STAI-S).We used a composite measure of verbal fluency comprising letter fluency and semantic fluency as the outcome measure.
Multiple regression analyses revealed higher fatigue was associated with better verbal fluency when STAI-S scores were high. We did not find a significant interaction between the FSS and CES-D.
Greater situational anxiety levels may buffer against the negative influence of fatigue on verbal fluency in non-clinical populations, consistent with previous research showing that moderate levels of anxiety can benefit cognitive function. Whether subthreshold depressive symptoms modify the association between fatigue and verbal fluency is still unclear. Measures that assess different symptom dimensions specific to depression would help to clarify this issue.