Critically ill patients might have impaired cerebral perfusion due to a risk factor known as blood pressure variability (BPV), which could be modified. For a study, researchers sought to investigate the relationship between BPV in the ICU and short- and long-term cognitive outcomes. Every single patient was younger than 50 years old. Delirium and reduced alertness that did not include delirium was the short-term’s cognitive endpoints. The result was a change in the slope of cognitive scores as a function of time over the long run. The key indicator of blood pressure variability (BPV) was systolic blood pressure’s average real variability (ARV). Both multivariable multinomial logistic regression and linear mixed-effects models were utilized to analyze the associations. Among 794 patients (1,130 admissions), 185 developed delirium, and 274 developed apathy. There was a dose-response relationship between 24-h systolic ARV and delirium (adjusted OR, 95% CI 2.15 per 5 mm Hg increase, 1.31–3.06, P<0.017) and depressed alertness (OR 1.89, 95% CI 1.18–3.03, P<0.008). For 371 patients with longitudinal cognitive scores, the cognitive decline accelerated after discharge (annual change OR −0.097, 95% CI −0.122 to −0.073). This acceleration increased as delirium severity increased (further decline of −0.132 [−0.233 to 0.030], P=0.011). After leaving the intensive care unit, investigators discovered no link between BPV and the patient’s cognitive trajectory. Delirium was more likely to occur in patients with BPV treated in the intensive care unit. On the other hand, BPV was not connected with a deterioration in cognitive ability over time.