Insomnia is common; in the typical pattern, a person wakes very early and cannot get back to sleep. Hypersomnia, or oversleeping, can also happen. Some antidepressants may also cause insomnia due to their stimulating effect. In severe cases, depressed people may have psychotic symptoms. These symptoms include delusions or, less commonly, hallucinations, usually unpleasant. People who have had previous episodes with psychotic symptoms are more likely to have them with future episodes.A depressed person may report multiple physical symptoms such as fatigue, headaches, or digestive problems; physical complaints are the most common presenting problem in developing countries, according to the World Health Organizations criteria for depression. Appetite often decreases, resulting in weight loss, although increased appetite and weight gain occasionally occur. Family and friends may notice agitation or lethargy. Older depressed people may have cognitive symptoms of recent onset, such as forgetfulness, and a more noticeable slowing of movements.Depressed children may often display an irritable rather than a depressed mood; most lose interest in school and show a steep decline in academic performance. Diagnosis may be delayed or missed when symptoms are interpreted as "normal moodiness." Elderly people may not present with classical depressive symptoms. Diagnosis and treatment is further complicated in that the elderly are often simultaneously treated with a number of other drugs, and often have other concurrent diseases. Cause
The biopsychosocial model proposes that biological, psychological, and social factors all play a role in causing depression.
Fomepizole, also known as 4-methylpyrazole, is a medication used to treat methanol and ethylene glycol poisoning. It may be used alone or together with hemodialysis. It is given by injection into a vein.Common side effects include headache, nausea, sleepiness, and unsteadiness. It is unclear if use during pregnancy is safe for the baby. Fomepizole works by blocking the enzyme that converts methanol and ethylene glycol to their toxic breakdown products.Fomepizole was approved for medical use in the United States in 1997. It is on the World Health Organizations List of Essential Medicines. Medical use
Fomepizole is used to treat ethylene glycol and methanol poisoning. It acts to inhibit the breakdown of these toxins into their active toxic metabolites. Fomepizole is a competitive inhibitor of the enzyme alcohol dehydrogenase, found in the liver. This enzyme plays a key role in the metabolism of ethylene glycol, and of methanol. Ethylene glycol is first metabolized to glycolaldehyde by alcohol dehydrogenase. Glycolaldehyde then undergoes further oxidation to glycolate, glyoxylate, and oxalate. Glycolate and oxalate are the primary toxins responsible for the metabolic acidosis, and for the renal damage, seen in ethylene glycol poisoning. Methanol is first metabolized to formaldehyde by alcohol dehydrogenase. Formaldehyde then undergoes further oxidation, via formaldehyde dehydrogenase, to become formic acid. Formic acid is the primary toxin responsible for the metabolic acidosis, and for the visual disturbances, associated with methanol poisoning.By competitively inhibiting the first enzyme, alcohol dehydrogenase, in the metabolism of ethylene glycol and  methanol, fomepizole slows the production of the toxic metabolites.