Blunted cerebral oxygenation during exercise in systemic lupus erythematosus patients

Subclinical brain lesions have been reported in systemic lupus erythematosus (SLE) patients. Advanced neuroimaging techniques have revealed microstructural and microvascular alterations. Most studies examining structural or functional brain abnormalities were performed either at rest or during a mental task. Our study aimed to examine possible differences in cerebral oxygenation during exercise between SLE patients without known neuropsychiatric manifestations and age-matched controls, using near-infrared-spectroscopy (NIRS) and examine possible underlying mechanisms through evaluation of brain derived neurotrophic factor (BDNF) levels.

The protocol involved a seated rest, a 3-min submaximal (30%) handgrip exercise, and a 3-min recovery. Continuous-NIRS was used to monitor changes in cerebral-oxygenated (O2Hb), de-oxygenated (HHb) and total-haemoglobin (tHb). BDNF levels were measured in serum samples.

Twenty-six SLE patients and 27 matched controls were enrolled. No differences were observed in baseline characteristics. During exercise, cerebral-O2Hb increased in both groups. However, SLE patients exhibited a significantly lower average- (1.20 ± 0.89 vs. 2.69 ± 2.46, p=0.001) and peak-O2Hb response (2.89 ± 1.56 vs. 5.83 ± 4.59, p=0.004) compared to controls. Serum BDNF levels were significantly lower in SLE patients compared to controls (p<0.01).

To our knowledge, this is the first study to evaluate cerebral oxygenation during exercise using NIRS in SLE patients compared to age-matched controls. Our data show that SLE patients even without overt neuropsychiatric manifestations exhibit a blunted increase in cerebral-O2Hb during a submaximal exercise stimulus. Examining brain oxygenation during a simple exercise task may assist in identifying patients with early alterations in cerebral function.