Ambien, the brand name for the generic drug zolpidem, binds to benzodiazepine-GABA receptors, a class of chemical receptors in the brain that reduces cell activity. Not surprisingly, several different parts of the brain downshift their excitability in response to the drug. These changes in excitability directly link to behavioral effects on sleep, learning and memory, impulsivity or anxiety, balance, and addiction.
Brain and Sleep
Sleep requires interactions between the deeper and superficial aspects of the brain. Ambien, popularly prescribed as a pharmacological treatment for insomnia, works in various brain circuits to produce immediate sedation, which facilitates the process of initially falling asleep and may assist in maintaining sleep throughout the evening.
Hippocampus and Cognition
Ambien produces unwanted side effects involving learning and memory. Information processing, the act of taking moment-to-moment experiences and packaging them into long-term memories, requires excitability in a seahorse-shaped structure of the brain called the hippocampus. Ambien has the potential to short-circuit hippocampal excitability in a way that interferes with memory consolidation. In fact, according to Sanofi-Aventis' Ambien information page, the drug might cause "blackout" periods of complete forgetfulness that last for hours when taken by early-day risers or travelers.
Amygdala and Impulsivity
Like alcohol, another drug that enhances inhibitory signaling, Ambien can increase impulsivity or outgoing behavior in acute and chronic users. Fear processing occurs in an almond-shaped "limbic" area of the brain called the amygdala, whose activation correlates with anxiety and stress. By impairing amygdala excitability, Ambien likely reduces fear enough to facilitate abnormal risk-taking behavior in some individuals.
Cerebellum, Thalamus and Dizziness
Ambien can cause dizziness and coordination problems that stem from the drug's actions in motor processing areas of the brain, such as the thalamus and cerebellum. These areas contribute to subjective feelings of balance and equilibrium. According to Dr. Stephanie Licata and her colleagues at Harvard Medical School, Ambien can conjure seasick-like episodes, where individuals feel dizzy, nauseous and confused.
Reward Center and Addiction
Individuals who take Ambien can develop psychological and physical dependences to the drug that ultimately result in the drug's abuse. Addiction in the brain occurs via the nucleus accumbens, also called the brain's reward center. In a review paper published in "Pharmacology, Biochemistry and Behavior," Dr. Licata and a Harvard colleague suggest that benzodiazepine drugs, including Ambien, might somehow promote activity in the nucleus accumbens in a way that increases the potential that people will want to take these drugs again.
References
- Sanofi-Aventis: Ambien Side Effects
- "Psychopharmacology"; A therapeutic dose of zolpidem reduces thalamic GABA in healthy volunteers: a proton MRS study at 4 T; Licata et al.; May 2009
- "Neural Plasticity"; Memory effects of benzodiazepines: memory stages and types versus binding-site subtypes; M. Savic et al.; 2005
- "Psychopharmacology"; Lorazepam dose-dependently decreases risk-taking related activation in limbic areas; Arce et al.; November 2006
- "Pharmacology, Biochemistry and Behavior"; Abuse and Dependence Liability of Benzodiazepine-type Drugs: GABA(A) Receptor Modulation and Beyond; S.C. Licata and J.K. Rowlett; July 2008
