General intelligence and short-term memory impairments in Post Traumatic Stress Disorder patients

Abstract

Background: Studies of the relationship between short-term memory and intelligence in Post Traumatic Stress Disorder (PTSD) patients are scarce.

Aim: (1) To explore whether people with PTSD have equivalent levels of short-term, non-verbal memory on the Benton Visual Retention Test (BVRT), and whether they have equivalent levels of intelligence on the Raven Standard Progressive Matrices (RSPM), (2) If memory deficit is evident in the PTSD group, is it related to intelligence on the RSPM compared to the control group?

Method: BVRT and RSPM were used with 30 PTSD patients, and 20 controls.

Results: There was no significant difference between the groups with respect to the RSPM. There was a significant difference between the groups with regard to the BVRT. In the PTSD group, there was a significant, negative, partial correlation between the BVRT sum of error scores from all forms, and the RSPM sum of correct scores from all sets. A regression model, controlled for co-linearity, was performed to assess the variables, which independently of each other would explain changes in the BVRT test performance in the PTSD group: Number of years of education, age, anxiety, and depression (from the General Health Questionnaire) were not significant, but RSPM test performance was correlated with BVRT test performance in the PTSD group.

Conclusion: People with PTSD had worse short-term, non-verbal memory on the BVRT, despite having comparable levels of intelligence on the RSPM. This could suggest focal deficits related to impact of trauma/PTSD on hippocampal function or a more general dysfunction. Memory deficits on the BVRT were related to intelligence on the RSPM for the PTSD group but not the control group. This could mean gross impairments in memory influence intelligence assessments in these patients.

Keywords:

• PTSD
• short-term memory
• intelligence
• brain
• hippocampus