The relationship between processing speed and working memory demand in systemic lupus erythematosus: evidence from a...

Area of Science:

• Neuropsychology
• Rheumatology
• Cognitive Neuroscience

Background:

• Working memory (WM) deficits are documented in systemic lupus erythematosus (SLE).
• The specific contribution of processing speed (PS) deficits to WM impairments in SLE remains unclear.

Purpose of the Study:

• To investigate if slower processing speed (PS) accounts for working memory (WM) deficits in patients with SLE.
• To differentiate between simple and complex PS and their impact on WM in SLE.

Main Methods:

• A visual n-back task assessed simple and complex PS and WM in 40 SLE patients and 36 healthy controls.
• Simple PS was measured by reaction time (RT) at 0-back; complex PS was measured by RT at 1-back and 2-back conditions.

Main Results:

• SLE patients showed impaired accuracy at high WM load (2-back) but not low loads.
• SLE patients exhibited slower RTs across all conditions, with greater slowing at higher WM loads.
• Even after accounting for simple PS, complex PS remained slower in SLE patients, and both PS measures correlated with poorer 2-back accuracy.

Conclusions:

• Processing speed deficits alone do not fully explain WM deficits in SLE.
• The n-back task effectively measures PS and WM in SLE.
• Disease duration, activity, and depression did not explain the observed PS and WM impairments.