Cognitive dysfunction in postural tachycardia syndrome

Abstract

Mental clouding is an almost universal complaint among patients with postural tachycardia syndrome (POTS) but remains poorly understood. Thus, we have determined whether POTS patients exhibit deficits during neuropsychological testing relative to healthy subjects. A comprehensive battery of validated neuropsychological tests was administered to 28 female POTS patients and 24 healthy subjects in a semi-recumbent position. Healthy subjects were matched to POTS patients on age and gender. Selective attention, a primary outcome measure, and cognitive processing speed were reduced in POTS patients compared with healthy subjects (Ruff 2&7 Speed t-score: 40±9 compared with 49±8; P=0.009; Symbol Digit Modalities Test t-score: 45±12 compared with 51±8; P=0.011). Measures of executive function were also lower in POTS patients (Trails B t-score: 46±8 compared with 52±8; P=0.007; Stroop Word Color t-score: 45±10 compared with 56±8; P=0.001), suggesting difficulties in tracking and mental flexibility. Measures of sustained attention, psychomotor speed, memory function or verbal fluency were not significantly different between groups. The present study provides evidence for deficits in selective attention and cognitive processing in patients with POTS, in the seated position when orthostatic stress is minimized. In contrast, other measures of cognitive function, including memory assessments, were not impaired in these patients, suggesting selectivity in these deficits. These findings provide new insight into the profile of cognitive dysfunction in POTS and provide the basis for further studies to identify clinical strategies to better manage the mental clouding associated with this condition.

Figure 1. Selective attention and cognitive processing speed are impaired in seated POTS patients

A, The Ruff 2&7 Speed measure of selective attention was significantly reduced in POTS patients compared to healthy subjects. B, The Symbol Digit Modalities measure of cognitive processing speed was also significantly lower in POTS. Values represent mean ± SD of t-scores normalized for age, gender and education. Dotted lines represent ±1 SD of mean.

Figure 2. Measures of executive function are reduced in seated POTS patients

The Trails B (A) and Stroop Word Color (B) measures of executive function were significantly reduced in POTS patients compared to healthy subjects. Values represent mean ± SD of t-scores normalized for age, gender and education. Dotted lines represent ±1 SD of mean.