Short-term memory is the ability to store sensory information for relatively short times, ranging from a few minutes to a few days. The main site for storing short-term memories is the hippocampus, a region in the brain's limbic system. In order to store new experiences in the hippocampus, the neurons in this area must form new neural networks. A neural network forms when proteins strengthen the neuron synapses, or projections. Most drugs that interfere with short-term memory prevents new neural networks from being formed by inhibiting or exciting neuron activity or metabolism below or beyond the normal levels.
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Benzodiazepines, a class of GABA agonists, bind to gamma-aminobutyric acid, or GABA, receptors in the brain. GABA is the brain's main inhibitory neurotransmitter. In the spine it ensures that light touch is not perceived as painful, and in the brain it inhibits hyper-excitability of neurons that could otherwise lead to seizures. Benzodiazepines have a similar effect. When injected directly into the spine, benzodiazepines function as strong pain relievers. When administered orally, they slow various regions of the brain, including the hippocampus. According to a review published in the November 2006 issue of the Scientific World Journal, this kind of drug-induced brain retardation inhibits the formation of new memories and the retrieval of old ones.
Imidazopyridines belong to a class of serotonin hypnotic drugs that are effect-related but chemically unrelated to benzodiazepines. The class is made up of zolpidem, or Ambien, saripidem, alpidem and ecopidem. Ambien, the best-known drug in this group, is prescribed for insomnia and other sleep disorders. Like benzodiazepines, imidazopyridines are GABA receptor agonists. They bind to the GABA receptor, which slows brain activity, including neuron activity in the hippocampus. According to a study published in the February 2007 issue of Clinical Toxicology, this can cause short-term memory loss and other forms of cognitive impairments.
Lithium salt is the oldest drug used to treat mental disorders. Coca-cola originally produced a drink called Lithia Coke that contained lithium, and 7UP was originally marketed as a hangover cure that contained lithium. Lithium was removed from 7UP in 1950. Lithium has anti-depressant and anti-mania effects. It's primarily prescribed for bipolar disorder, cyclic major depression and schizo-affective disorder. Lithium decreases the brain levels of serotonin, dopamine and the stress hormone norepinephrine. According to reviews published in Lithium in Neuropsychiatry, the main side effects of lithium salts are muscle tremors, the movement coordination disorder visual ataxia, hypothyroidism, weight gain and short-term memory loss.
Gabapentin is a GABA analogue that increases the production of GABA by modulating GABA enzymes. The drug is approved for neuropatic, or nerve-related, pain, as part of a treatment plan for methamphetamine and cocaine addiction, and as a secondary line of treatment for partial seizures. One of the side effects of gabapentin is short-term memory loss, according to a study published in the March 2006 issue of British Journal of Ophthalmolology. Increased levels of GABA inhibit neuron activity in the hippocampus, interfering with short-term memory formation.
Ecstasy is an illegal drug widely used in dance clubs in major cities. It gives rise to a feeling of euphoria and a sense of trust and intimacy with others. It blocks the breakdown of dopamine, serotonin and norepinephrine and also has some affinity for serotonin receptors. When it binds to serotonin receptors, it leads to an increase in the brain levels of the cuddle hormone oxytocin. Ecstasy also has significant side effects, including short-term memory loss, reports a study in the February 2010 issue of the Journal of Psychopharmacology. Users of ecstasy more often forget to carry out intended actions, researchers found.
- "The Scientific World Journal"; Anterograde and Retrograde Effects of Benzodiazepines on Memory; Daniel Beracochea; November 2006
- "Clinical Toxicology"; Compulsive Activity and Anterograde Amnesia after Zolpidem Use; Tsai, et al.; February 2007
- "Lithium in Neuropsychiatry: The Comprehensive Guide"; Michael Bauer; 2006
- "British Journal of Ophthalmology"; The effects of gabapentin and memantine in acquired and congenital nystagmus: a retrospective study; Shery, et al.; March 2006
- "ournal of Psychopharmacology"; Everyday and Prospective Memory Deficits in Ecstasy/Polydrug Users; Florentia Hadjiefthyvoulou, et al.; February 2010