<unk>  is a form of<unk>  which can result from<unk>  or methamphetamine use. Typically it appears after large doses or chronic use, although in rare cases some people may become psychotic after relatively small doses. Other chemicals or drugs which similarly increase dopamine function (such as cocaine and L-DOPA) can produce similar psychotic states. Because of this, the term stimulant<unk>  is sometimes preferred.<unk>  can include delusions, hallucinations and thought disorder. This is thought to be largely due to the increase in dopamine and perhaps serotonin activity in the mesolimbic pathway of the brain caused by<unk> -like drugs, although other factors such as chronic sleep deprivation may also play a part. The link between<unk>  and<unk>  is one of the major sources of evidence for the dopamine hypothesis of<unk> .
The link between<unk>  and<unk>  was first made by Young and Scoville in 19381 and was originally considered to be a rare condition. As<unk>  use increased after World War II, largely due to the widespread use of<unk>  compounds in nasal decongestant and dieting preparations, it became clear that chronic<unk>  use often led to psychotic symptoms.
Hallucinations are frequently reported in chronic<unk>  users, with over 80% of users reporting the presence of hallucinatory experiences2, typically as visual or auditory experiences. Delusions, paranoia, fears about persecution, hyperactivity and panic are also reported as the most common features3
Concurrent to having delusions and hallucinations, chronic<unk>  users may also display stereotyped, repetitive and seemingly purposeless movements, known as 'motor stereotypies' or more commonly as 'knick knacking', 'tweaking' or being 'hung-up'. These may include examining, sorting, disassembling, and cleaning.  The article on punding gives a more complete description of this behavior. This behavior may be similar to the symptoms of  OCD.
One particular manifestation of<unk>  associated with<unk>  use is delusional parasitosis or Ekbom's syndrome, where a person falsely believes themselves to be infested with parasites. However, related behaviour may occur in non-psychotic conditions, where users will realise they are not infested by parasites but will pick at their skin anyway. This more closely resembles obsessive-compulsive disorder.
Amphetamine psychosis
Opioid withdrawal
Cocaine withdrawal
Other hallucinogen use disorder
Opiate withdrawal
Alcohol withdrawal
Suicide crisis
Marijuana intoxication