Recognizing Post–COVID-19 Brain Fog in Older Adults

The onset of neurocognitive changes in older adults can be due to many different etiologies. Early recognition of such changes is essential in making an accurate diagnosis and managing these conditions. An essential part of the practice of geriatric medicine is the ongoing need to recognize these often subtle changes in cognition and scrupulously review the patient’s recent clinical course to determine the nature of these cognitive changes. The necessity for this practice cannot be understated. Frequently, the causes of a change in a patient’s level of cognition are likely the result of a change in his or her medication regimen or an acute process, or the chronic sequelae of such. The following case report illustrates the elusive nature of such neurocognitive change and the need for ongoing review and assessment.

Mrs. AC was an 83-year-old woman who was living independently in her apartment since her husband’s death 10 years earlier. She was independent in all of her activities of daily living (ADLs), including processing her own mail and shopping for groceries with only minimal assistance. She had a medical history significant for hypertension, degenerative joint disease, and constipation.

Mrs. AC was admitted to the hospital for evaluation of chest pain. After evaluation from the cardiologist, her condition was diagnosed as acute myocarditis. She had a positive test for COVID-19. She remained hospitalized for 5 days, during which time her chest pain symptoms gradually resolved, and she was discharged home in stable condition upon testing negative for COVID-19. Several days after discharge, a neighbor observed that Mrs. AC appeared disheveled and disoriented and called an ambulance. At the hospital, an inpatient workup was conducted; a brain computed tomography (CT) scan was negative for an acute cerebrovascular event, and a COVID-19 test remained negative. The hospital team determined that Mrs. AC was unable to care for herself independently and was discharged to a subacute rehabilitation facility. Her medications upon admission included amlodipine (5 mg daily), hydrochlorothiazide (12.5 mg daily), omeprazole (20 mg once per day), calcium with vitamin D supplement (twice a day), and a multivitamin.

After a successful course of skilled rehabilitation, the psychiatry team evaluated Mrs. AC for discharge to her home. She presented as awake, alert, and oriented to person and place. Her Mini-Mental State Examination score of 24 out of 30 indicated significant deficits in concentration and inattention. She appeared confused and exhibited difficulties with judgement and following directions. The interdisciplinary team felt that she was not safe to return home alone due to her cognitive decline. Following extensive discussions with her proxy, Mrs. AC was transferred into a skilled nursing facility for long-term care, a decision that also granted more time to consider the best options for Mrs. AC’s long-term care needs.

During her stay at the skilled nursing facility, a medical workup commenced, including a comprehensive medication review, to determine the cause of her new-onset cognitive decline and confusion. A brain CT scan revealed mild atrophic changes, but laboratory tests for serum electrolytes, vitamin B₁₂, folate, and thyroid-stimulating hormone levels were within the normal range.

Approximately 4 months later, Mrs. AC’s cognition gradually improved and she became more independent in all ADLs. On follow-up, the psychiatrist reported that Mrs. AC’s clinical presentation significantly improved and assessed that she could return home and live independently with home care services in place.

This case illustrates the importance of comprehensive geriatric medical assessments in older adults before hospital discharge. Upon her first admission to the hospital, Mrs. AC was erroneously discharged home and then subsequently readmitted due to neurocognitive declines that emerged either during or following COVID-19 infection. A medical assessment process must take place across the spectrum of health care delivery, whether in the office, acute-care, or long-term care setting. Patients may visit different health care settings for specific issues, and subtle changes in cognition can often be missed. The differential diagnosis for new-onset neurocognitive changes following an acute hospitalization for COVID-19 includes post–COVID-19 brain fog, delirium, and post–intensive care syndrome (PICS).¹ We review each of these differential diagnoses below.

Post–COVID-19 Brain Fog

Post–COVID-19 brain fog is defined by the National Institute for Health and Clinical Excellence, the Scottish Intercollegiate Guidelines Network, and the Royal College of General Practitioners as “signs and symptoms that develop during or after an infection consistent with COVID-19, continue for more than 12 weeks, and are not explained by an alternative diagnosis.” COVID-19 brain fog, which can have varying presentations, is described as a feeling of “mental slowness” and difficulty with concentration.² Furthermore, COVID-19 infection may have understated long-term effects on the brain, such as persistent impairment in sustained attention or cognition. One study found that in more than 90% of patients, abnormalities in ADLs, functional outcomes, anxiety, depression, and sleep occurred 6 months after hospitalization for COVID-19. A recent meta-analysis found that over one-fifth of people recovering from COVID-19 exhibited cognitive impairment 12 or more weeks following diagnosis.³ Moreover, a significant association was found between patients reporting post–COVID-19 brain fog and the severity of their illness, intensive care unit (ICU) admission, female sex, and the presence of respiratory symptoms at the onset of the illness.² These findings may help predict which patients are more likely to develop severe post–COVID-19 brain fog.

Post–COVID-19 brain fog is one manifestation of postacute sequelae of SARS-CoV-2 (PASC), the onset of new symptoms that develop after recovery from an acute infection with SARS-CoV-2. The pathophysiology remains unclear and poorly defined. Because PASC has a vague clinical presentation and insidious onset, it is difficult to assess and identify this diagnosis. Furthermore, providers are challenged by the lack of treatment options available, and care is usually supportive in nature.⁴

Delirium

Delirium is characterized by an acute and fluctuating change in awareness, attention, and cognition that cannot be explained by a preexisting neurocognitive disorder.⁴ Delirium can be induced by infection, metabolic abnormalities, medications, or drug withdrawal. It can be exacerbated by predisposing factors, such as underlying preexisting cognitive impairment. The current management techniques of delirium are medication review, managing distress, mitigating complications, maintaining engagement to environmental issues, and treating precipitating conditions (eg, infections).⁵ Delirium differs from post–COVID-19 brain fog in that it fluctuates in its clinical presentation and is associated with either hyperactivity or hypoactivity. The symptoms differ such that delirium can present as a rapid change in attention, awareness, and cognition rather than an indolent “mental slowness” or “spaced out” feeling.

Post–Intensive Care Syndrome

Clinically, PICS is seen as decline in function developing after critical illness, which can involve cognitive decline, psychiatric decline, or physical weakness. In a prospective study of more than 800 patients admitted to the ICU with shock or respiratory failure, or both, 26% of survivors had deficits consistent with mild dementia upon discharge compared with 6% upon admission.⁶ PICS can be identified immediately following a critical illness or can go unrecognized for a period of time, and it may take many months to completely resolve. Attention or concentration, memory, mental processing speed, and executive function are the most common areas of cognition affected in PICS. The severity ranges from mild to significant in affecting a patient’s ability to perform complex executive tasks or ADLs, or both. One study found that after 3 years of follow-up in patients with PICS, 15% had a dementia diagnosis compared with 12.2% in the general population.⁷ The loss of memory and executive function are major hurdles to recovery and impair patients from participating in their discharge plan.

Post–COVID-19 brain fog has emerged as a prevalent neurocognitive syndrome following acute COVID-19 infection in the aftermath of the global pandemic. In some instances, symptom onset may be gradual. Given Mrs. AC’s relatively brief and benign hospital course—which did not progress to critical illness—lack of ICU admission, and insidious onset of symptoms, post–COVID-19 brain fog is the likely etiology of her clinical presentation, which had originally gone unrecognized.

Zachary Palace, MD, CMD, FACP¹ • Mariel Liebeskind, MPH²

Affiliations:

¹Department of Medicine, Hebrew Home at Riverdale, Bronx, NY

²Department of Medicine, SUNY Upstate Medical University, Syracuse, NY

Disclosure:

The authors report no relevant financial relationships.

Address correspondence to:

Zachary Palace MD, Medical Director
Hebrew Home at Riverdale
5901 Palisade Ave Bronx, NY 10471
Phone: 718-581-1200
Email: zachary.palace@hebrewhome.org

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