Methamphetamine is a neurotoxin of the phenethylamine and amphetamine classes that is used as a recreational drug and, rarely, to treat attention deficit hyperactivity disorder (ADHD) and obesity.
In low doses, methamphetamine can cause an elevated mood and increase alertness, concentration, and energy in fatigued individuals. At higher doses, it can induce psychosis, rhabdomyolysis and cerebral hemorrhage.
Recreationally, methamphetamine is used to increase sexual desire, lift the mood, and increase energy, allowing some users to engage in sexual activity continuously for several days straight.
Methamphetamine may be sold illegally, either as pure dextromethamphetamine or in an equal parts mixture of the right and left handed molecules (i.e., 50% levomethamphetamine and 50% dextromethamphetamine). Both dextromethamphetamine and racemic methamphetamine are schedule II controlled substances in the United States. Similarly, the production, distribution, sale, and possession of methamphetamine is restricted or illegal in many other countries due to its placement in schedule II of the United Nations Convention on Psychotropic Substances treaty.
Toxicity to Neurons
Unlike amphetamine, methamphetamine is directly neurotoxic to dopamine neurons. Moreover, methamphetamine abuse is associated with an increased risk of Parkinson's disease due to excessive pre-synaptic dopamine autoxidation, a mechanism of neurotoxicity.
Similar to the neurotoxic effects on the dopamine system, methamphetamine can also result in neurotoxicity to serotonin neurons. It has been demonstrated that a high core temperature is correlated with an increase in the neurotoxic effects of methamphetamine. As a result of methamphetamine-induced neurotoxicity to dopamine neurons, chronic use may also lead to post acute withdrawals which persist beyond the withdrawal period for months, and even up to a year.
The psychological effects of methamphetamine can include euphoria, dysphoria, changes in libido, alertness, apprehension, concentration, decreased sense of fatigue, insomnia or wakefulness, self-confidence, sociability, irritability, restlessness, grandiosity and repetitive and obsessive behaviors. Methamphetamine use also has a high association with anxiety, depression, methamphetamine psychosis, suicide, and violent behaviors. Methamphetamine also has a very high addiction risk.
Use can result in a psychosis which may present with a variety of symptoms (e.g. paranoia, hallucinations, delirium, delusions). A Cochrane Collaboration review on treatment for amphetamine, dextroamphetamine, and methamphetamine abuse-induced psychosis states that about 5–15% of users fail to recover completely. The same review asserts that, based upon at least one trial, antipsychotic medications effectively resolve the symptoms of acute amphetamine psychosis. Methamphetamine psychosis may also develop occasionally as a treatment-emergent side effect.
Capgras Syndrome is a misidentification syndrome where a person believes that an acquaintance or a close family member, has been replaced by an identical looking imposter.
This syndrome can be transient, developing after a brain injury, or can take a chronic form where the delusion is long standing. The syndrome is named after Joseph Capgras lived 1873-1950 French psychiatrist who first described the disorder in a 1923 paper and used the term ‘illusion of doubles’ to describe a case of woman who had various doubles that had taken the place of people she knew.
Occasionally Capgras syndrome may include inanimate objects such as chairs and animals or places can be seen as duplicate imposters. They may even misidentify or not recognize mirror images. In some cases, if the Capgras sufferer can be convinced that one person is not an imposter, they will transfer the Capgras delusion with someone else. This is also called Delusional Misidentification Syndrome (DMS)
Capgras syndrome (CS) is more commonly associated with neurodegenerative diseases, especially Lewy body disease, where visual hallucinations always coexist. In the absence of a neurodegenerative disease, the onset of Capgras syndrome occurs at a significantly younger age and can be associated with psychiatric disease, cerebrovascular events, and illicit drug use.
Cases of CS can be identified immediately after methamphetamine (METH) use and even in the context of cocaine overdose, administration of morphine and ketamine due to their neurodegenerative effects. Symptoms of Capgras may often occur months after use of neurodegenerative drug use stops as a long term effect that may be associated with damage to Medulla neuron degeneration and psychological distress that interruption may cause in the degeneration of neurons used in the intimate recognition processing factors of close friends or relatives.
Another result of neuron damage may manifest as Fregoli delusion, or the delusion of doubles. It is a rare disorder in which a person holds a delusional belief that different people are in fact a single person who changes appearance or is in disguise. The syndrome may be related to a brain lesion or neuron degeneration from drug use. There may be paranoid nature delusion where a person believes themselves persecuted by the person they think is in disguise as someone else.