Mental fatigue is a pervasive consequence following subarachnoid hemorrhage (SAH) that significantly impacts patients’ quality of life. This study aims to investigate the underlying mechanisms of mental fatigue. First, we investigate the presence of deficits in processing speed and attention in patients with aneurysmal (aSAH) or angiography-negative subarachnoid hemorrhage (anSAH). Second, we explore whether processing speed and attention are related to cognitive complaints and mental fatigue.

The study sample comprised of patients with aSAH or anSAH without previous psychological or neurological problems. Neuropsychological assessments were conducted five months post-SAH. Processing speed was assessed using the Trailmaking Test Part A (TMT-A) and Reaction Time tasks S1 (RTs1) and S2 (RTs2) from the Vienna Test System (VTS). Attention was assessed using the Trailmaking Test Part B (TMT-B) and Reaction Time task S3 (RTs3) and Determination Test (DT) of the VTS. Additionally, three items from the Checklist for Cognitive and Emotional Consequences following stroke (CLCE-24) were used to measure subjective complaints in processing speed and attention. Mental fatigue was measured using the Dutch Multifactor Fatigue Scale (DMFS).

A total of 87 patients (61 aSAH and 26 anSAH) were included. Patients with aSAH scored significantly worse compared to the control group on all measures of processing speed and attention (p <.001). Similarly, patients with anSAH displayed significant deficits on the RTs1, RTs2, DT and TMT-B (p<.001). No significant differences were found between the two patient groups. Furthermore, poorer performance on all tests of processing speed and attention was associated with increased mental fatigue (p<.05). Worse performance on the RTs1, RTs2 and DT were related to more subjective complaints. A strong correlation between mental fatigue and subjective complaints was found (r = .691).

These findings are in line with the coping hypothesis, which suggests that patients may use more mental effort to compensate for reduced processing speed or attention.  This heightened mental effort could be experienced by the patient as mental fatigue or cognitive complaints. This research provides more insight in the relations between cognitive deficits, cognitive complaints and mental fatigue post-SAH, offering valuable insights for clinical interventions.