Impact of COVID-19 on neurological, psychological and other mental health outcomes

Chronic effects of COVID-19 can lead to a prolonged inflammatory state, which can increase symptoms resembling an autoimmune disorder.

[1] Many patients with COVID-19 experience psychological symptoms that can arise either from the direct actions of the virus, the chronic increase in inflammation or secondary effects, such as post-traumatic stress disorder.

[2] SARS-CoV-2 can be detected in the brain and cerebrospinal fluid acutely by polymerase chain reaction, and is thought to enter via the olfactory system.

[10] The cases of myelitis could arise from direct infection of muscle via local angiotensin-converting enzyme 2, the receptor for SARS CoV-2.

Patients who experience of loss of smell for longer than two weeks are recommended to obtain olfactory training.

[14] Personal accounts of the process of olfactory training post COVID-19 infection have been covered in media outlets such as the New York Times.

[15] Patients experiencing loss of smell for more than 2 weeks are also recommended to obtain a referral to an ear nose and throat (ENT) physician.

[14] alpha-lipoic acid is another remedy that has been proposed, but the accumulated literature on this suggests that it does not improve symptoms or recovery.

Further, since incidence appears to be correlated with severity of infection, it is lower in vaccinated groups, on reinfection and during the omicron era, meaning that the time when data was recorded is important.

In the United States in June 2023, 6% of the population indicated having long COVID, as defined as symptoms that last for 3 months or more.

[28][16] Neuroinflammation as a result of viral infection (e.g., influenza, herpes simplex, and hepatitis C) has been linked to the onset of psychiatric illness across numerous publications.

[29] Psychotic disorders are characterized by neuroinflammation, more specifically maternal inflammation, and abnormally high mesolimbic dopamine (DA) signaling.

[29] Excess inflammation following a COVID-19 infection can alter neurotransmitter signaling which contributes to development of psychotic and mood related disorders.

[30] About 20% of COVID-19 cases that pass through the intensive care unit (ICU) have chronic neurologic symptoms (beyond loss of smell and taste).

[31] A large scale study of 6,245,282 patients have revealed an increased risk of Alzheimer's disease diagnosis following COVID-19 infection.

[41] A 2021 article published in Nature reports increased risk of depression, anxiety, sleep problems, and substance use disorders among post-acute COVID-19 patients.

[14] These accumulated problems lead to a general (and quantified) reduction in the quality of life and social functioning (measured with the SF-36 scale).

[14] There is also increasing evidence to suggest that ongoing psychiatric symptoms, including post-traumatic stress[43] and depression,[44] may contribute to fatigue in post-COVID syndrome.

[47] In October 2024, a paper published in Nature Translational Psychiatry studied brain and cognitive changes from Italian adolescents and young adults before and after a COVID infection.

The cohort was obtained by convenience sample from another study, which was evaluating the effects of heavy metal exposure in Northern Italy.

In addition to MRI scans, the cohort was also tasked with completing the Cambridge Neuropsychological Test Automated Battery (CANTAB).

[51][52] Another study identified neuroinflammation and an activation of adaptive and innate immune cells in the brain stem of COVID-19 patients.

A study revealed that patients recovering from COVID-19 who experienced anosmia during the acute episode exhibited impulsive decision-making, functional brain alterations, cortical thinning, and changes in white matter integrity.

[56][57] An April 2023 study published in Journal of the National Medical Association performed a quantitative secondary analysis on data collected from the Household Pulse Survey (HHPS) between June and October 2022.

A logistic regression analysis was conducted on responses to Phase 3.6 which includes questions on long COVID symptoms, vaccinations, and demographic characteristics.

Factors such as socioeconomic status, healthcare access, and occupational exposure are critical in understanding these disparities, as they can influence both the likelihood of contracting COVID-19 and the severity of its long-term effects.

Overall, an understanding of the social determinants of health is needed to comprehensively address cognitive effects of Long COVID.