Cognitive impairment after long COVID-19

COVID-19 is caused by the SARS-CoV-2 virus (a respiratory infectious disease)

Cognitive impariment after COVID-19

• most patients recover following COVID-19 with no sequelae - however there is growing evidence that COVID-19 may result in cognitive impairment (1)
  • individuals with cognitive impairment following COVID-19 experience cognitive deficits, such as:
    • diminished memory and attention
    • sleep disturbances
  • a review notes that (2)
    • cognitive problems are common after acute SARS-CoV-2 infection
      • study evidence suggests up to one third of patients with long COVID have cognitive impairment - however the review notes that estimates vary widely and are complicated by methodological heterogeneity—eg, study size, assessment approach, follow-up duration
    • most frequent symptoms seem to affect memory, attention, and concentration
    • discrete impairments are also seen in attentional and executive processing different types of memory, visuospatial processing, and language
    • linked systemic symptoms such as fatigue, insomnia, and a general befuddled state frequently termed “brain fog” are commonly reported
    • symptoms tend to improve, but this may take up to a year
      • individuals with chronically persistent symptoms lasting more than 12 months have a lower chance of improving
    • symptoms usually fluctuate
  • evidence indicates that COVID-19 may contribute to cognitive decline by damaging crucial brain regions, including the hippocampus and anterior cingulate cortex (1)
  • study evidence has identified active neuroinflammation, mitochondrial dysfunction, and microglial activation in COVID-19 patients, implying that these factors may be potential mechanisms leading to cognitive impairment (1)

Note that before considering cognitive impairment as secondary solely (or partly) due to COVID-19 that the clinician must (2):

• seek to exclude non-specific cognitive blunting from other underlying causes
  • exclude specific metabolic, toxic, or (patho)physiological causes
  • consider that poor sleep, diet, smoking, alcohol, and recreational drug use, reduced activity levels, and low exposure to natural light may also contribute

Reference:

1. Li Z, Zhang Z, Zhang Z, Wang Z, Li H. Cognitive impairment after long COVID-19: current evidence and perspectives. Front Neurol. 2023 Jul 31;14:1239182
2. Ladds E, Darbyshire J L, Bakerly N D, Falope Z, Tucker-Bell I. Cognitive dysfunction after covid-19 BMJ 2024; 384 :e075387 doi:10.1136/bmj-2023-075387