https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5830056/

"Statins and reversible cognitive impairment – evidence for
Statins have been linked to short-term reversible cognitive impairment since early safety and tolerability testing [13]. During a phase I clinical trial of atorvastatin, escalating doses showed a dose-dependent adverse reaction of mild, transient, restlessness, euphoria, and mental confusion [13]. However, cognitive impairment was not reported significantly enough in the in phase II and III statin clinical trials to be recognized as a side effect [9–11]. Post-marketing surveillance can uncover side effects not identified in clinical trials and post-marketing surveillance of statins has revealed numerous case reports that characterize a transient and reversible cognitive loss. A review of 60 case reports described the main symptom of short-term memory loss that occurred a few months after the start of statin therapy or after an increase in dosage. Several case reports observed resolution of cognitive impairment upon discontinuation of the statin and recurrence of cognitive impairment upon rechallenging of the statin [14].

A double blind placebo-controlled trial of lovastatin’s effect on cognitive functioning and mood showed detrimental effects on cognitive performance on four neuropsychological tests assessing attention, working memory, and overall mental efficiency [15]. A follow up double blind, randomized trial found a significantly worsened learning effect in participants taking statins compared to placebo [16]. The participants on statins were not able to learn from prior experiences as well as those on placebo. The strength of evidence is heightened by the randomization and controlled structure in these studies however, the strength of evidence is lowered by the small population of only 308 participants.

A patient survey-based analysis found evidence of cognitive impairment with variable onset and recovery courses, a clear relation to statin potency, and a significant negative impact on quality-of-life [17]. The Naranjo adverse drug reaction probability scale [18] was used to describe the relationship between statins and cognitive impairment. The Naranjo score is widely recognized as an accepted tool to measure the correlation between an adverse event and a medication increasing the strength of this evidence. Seventy-five percent of the cognitive adverse drug reports were determined to be probably or definitely related to statin therapy. In some patients, a diagnosis of dementia or Alzheimer’s disease was reportedly reversed upon discontinuation of the statin. Patients whose symptoms improved after discontinuation reproduced the symptoms after the statin was rechallenged. Some of those patients were rechallenged multiple times with continued recurrence of the adverse effect. Quality-of-life measures were significantly reduced in these patients, establishing the seriousness of this potentially avoidable adverse effect [17]."

https://www.npr.org/2023/02/17/1157773608/the-presidents-personal-physician-has-issued-biden-a-clean-bill-of-health