Abstract

Objective: The purpose of this article is to examine how psychosocial distress and HSV-1 might interact to foster early cognitive vulnerability in otherwise healthy middle-aged adults. Several environmental risk factors, including mental stress and chronic viral infections, can increase cognitive vulnerability and lead to cognitive decline. Considering the anticipated dramatic increase in the number of older adults with dementia in the next 40 years and the current lack of dementia cures, it is imperative that we explore any modifiable risk factors for brain vulnerability that may facilitate the development of interventions to prevent or delay the onset of severe cognitive impairment.
Methods: A total of 113 participants, 63 female and 50 male, were recruited for this study. 15 cc of blood was obtained by venipuncture from consenting volunteers and screened with the ELISA tests to assess seropositivity for HSV-1 IgG antibodies. Cognitive vulnerability was operationalized as lower cognitive function across any of the following 3 domains: global, memory, executive function. The Beck Depression Inventory (BDI-II) was used to assess depressive symptoms.
Results: After controlling for age, gender, and education, there was a significant main effect for HSV-1, F(1,106)=7.908, p=0.01, but not for depressive symptoms, on global cognition. However, this main effect was qualified by a statistically significant interaction between the factors, F(1,106)=5.046, p=0.03. No significant main effects or interactions were found for memory or executive function.
Conclusion: The results of this study show that even subclinical depressive symptoms can exacerbate the negative effect of HSV-1 infection on global cognitive function. We found that seropositive individuals reporting at least some depressive symptoms exhibited worse performance on a test of intelligence than seropositive individuals without depressive symptoms.

Keywords: Depression; Executive function; Memory; Cognitive impairment; Dementia; Middle-age adult; Global cognitive function