User:Aagig12/Ageusia/sandbox

Lead
Ageusia [uh-gyoo-zee-uh, -zhee-uh, -zhuh], is a gustatory disorder characterized by the inability to detect tastes such as sweetness, saltiness, sourness, bitterness, and umami. It is generally considered rare and can impact individuals of any age or demographic. Due to the COVID-19 pandemic, there has been an increase in reported cases of ageusia, making it more commonly diagnosed than before.

 Causes 

Ageusia can arise from various factors:


 * Issues with the water-soluble molecules responsible for taste, causing oral dryness or damage to taste buds.
 * Radiation therapy treatments.
 * Facial nerve damage due to surgery.
 * Head traumas, traumas to middle ear or jaw.
 * Sinusitis, strep throat, salivary gland infections, common cold, influenza, and COVID-19.
 * Bell's palsy or dental procedures like a molar extraction and tonsillectomy.
 * Epilepsy, tumors, stroke, or multiple sclerosis.
 * Diseases that can affect the autonomic nervous system, like diabetes.
 * Some medications, including muscle relaxants, chemotherapy medication, anti-fungal, chemical compounds found in anti-depressants, anti-seizure medications, and blood pressure medications.
 * Sialadenitis, gingivitis, oral infections, or glossodynia (burning mouth syndrome (BMS)).

Ageusia resulting from a significant head injury is relatively uncommon, affecting only around 1% of individuals with this type of injury.

 Neural Pathways of Taste 

The three nerves associated with taste are the facial nerve (cranial nerve VII), which provides fibers to the anterior two-thirds of the tongue; the glossopharyngeal nerve (cranial nerve IX), which provides fibers to the posterior third of the tongue; and the vagus nerve (cranial nerve X), which provides fibers to the epiglottis region. Taste fibers categorize as special visceral afferent (SVA).

A clinician can examine the integrity of the nerves associated with taste (specifically the facial nerve and glossopharyngeal nerve) with a suprathreshold taste test. Edible strips placed on specific regions of the patient’s tongue contain the five taste qualities (sweet, salty, bitter, sour, umami). The strips provide stimulation slightly above the threshold for taste. If a patient can properly identify a taste, this is considered a normal result. This test has been proven to be decidedly sensitive for analyzing taste recognition.

 Proposed Mechanism 

Some research indicates that the cellular distribution of taste cells and ACE2 receptor distribution is involved in ageusia. They found that the percentage of ACE2 positive cells was higher in taste cells, which indicated that SARS-CoV-2 might invade them and lead to ageusia in these patients. However, data regarding the exact mechanism by which SARS-CoV-2 determines ageusia is limited. The virus may bind to the sialic acid receptors and occupy and accelerate the degradation of the gustatory particles, leading to a decrease in taste sensation.

Ageusia and hypogeusia might result from disruptions in saliva composition and volume, as well as compromised epithelial cells of the tongue. On the other hand, dysgeusia may stem from isolated injury to any one of the major nerve pathways involved in taste perception.

 COVID-19 and Ageusia 

Ageusia can be an indication of a COVID-19 infection. Ageusia and anosmia are among the prominent symptoms commonly associated with COVID-19, with symptoms that could last up to 4 weeks. However, it is noteworthy that ageusia may manifest differently from anosmia, as anosmia primarily affects the olfactory system versus ageusia primarily affecting the gustatory receptors. As a result, emerging research indicates that the various variants of COVID-19 might be associated with differences in the severity of ageusia experienced by patients, as well as the severity of other taste and smell disorders. Implying that certain strains of the virus may have differing impacts on the sensory functions of affected individuals.

The duration of ageusia recovery can vary significantly depending on cause of infection. In a COVID-19-related infection, the recovery timeline for ageusia can vary among individuals, influenced by factors such as variants or strains of the virus, individual immune responses, demographic characteristics, and other factors.

 Statistics (not putting in article) 

Research exploring the prevalence of taste disorders resulting from the COVID-19 pandemic suggests that a diverse range of individuals were affected. In European patients, the prevalence was reported at 55.2%, while in North American patients, it was 61.0%. Among Asian patients, the prevalence was lower at 27.1%, and similarly, in South American patients, it was 29.5%. Australian patients exhibited a prevalence of 25.0%. Furthermore, specific types of taste disorders were also noted, with ageusia observed in 28.0% of patients, hypogeusia in 33.5%, and dysgeusia in 41.3%.

Comparisons among the different taste disorders show that dysgeusia, characterized by altered or distorted taste perception, exhibits a higher prevalence (41.3%) compared to ageusia (28.0%) and hypogeusia (33.5%) among patients with COVID-19 infection. The exact mechanisms underlying the differential presentation of taste disorders in these patients remain uncertain, but several potential explanations exist. All three types of taste disorder could arise from damage along the central taste pathway, involving areas such as the brainstem, thalamus, cranial nerves, or cerebral cortex. Previous evidence suggests that cerebral involvement in COVID-19 may occur during both early and late stages of the infection.

Proposed Mechanisms
Recent research has hinted at a connection between the distribution of taste cells and ACE2 receptors in ageusia. Higher amounts of the receptors suggests an easy route for a COVID-19 infection with a possible outcome of ageusia.

Ageusia could also possibly occur due to changes in the abundance or lack of saliva that can eventually cause damage to the cells on the tongue's surface.

Saliva and Taste Perception
Saliva is essential in taste sensation and perception. Studies have indicated that saliva plays a critical role in detecting a COVID-19 infection, and ageusia can serve as an indication of an infection that is affecting the salivary glands.

However, there is still insufficient research to fully clarify the full effects of ageusia, COVID-19, and their potential impacts on saliva and 'salivary flow rate.'

Zinc Deficiency
In cases of zinc deficiency, a shortage of zinc-binding proteins that help with the growth and development of taste buds, could result in taste bud issues associated with ageusia, hypogeusia, and hyposalivation.

Low levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which help with the growth of taste buds, in saliva have also been linked to ageusia.

Treatments
Treatment for ageusia varies depending on its cause, whether it stems from certain illnesses, medications, traumatic injuries or other causes.

If ageusia is triggered by a medication prescribed to a patient, discontinuing the medication under the guidance of a healthcare professional may alleviate the symptoms. Switching to an alternative medication can also help resolve the issue. In cases where ageusia is associated with an underlying illness or trauma, some medications can also help alleviate symptoms. Some of these medications include, antihistamines, decongestants, and antibiotics.

 Diagnosis 

An example of a test used by researchers and doctors is electrogustometry. This test involves applying mild electric currents to specific tongue areas, to assess taste sensitivity in patients exhibiting ageusia and its symptoms.

Another test that can be used to detect the severity of an individuals ageusia is an 'suprathreshold taste test,' also known as a edible strip taste test. The edible strip is placed on the individuals tongue and it contains various flavors for the patient to be able to detect, or not able to detect.

Complications
People experiencing ageusia can endure daily discomfort, which frequently diminishes their enjoyment of eating. This discomfort can cause many individuals affected by taste disorders with feelings of:


 * Isolation in individuals experiences
 * Feelings of depression
 * Social withdrawal
 * Unhealthy eating habits

Such eating habits may involve either insufficient food intake or excessive consumption of sour or sweet foods. This dietary pattern could pose risks, particularly for individuals with diabetes.

Ageusia and Diabetes
Diabetes has been shown to sometimes lead to ageusia, often starting with fluctuations in glucose levels. When blood sugar levels fluctuate, it can disrupt the taste buds, making it difficult to detect flavors. But not everyone with diabetes will experience this. The severity of an individuals ageusia or other taste dysfunction can differ from person to person.