Individual Differences: Stress Flashcards
HPA
Hypothalamic pituitary adrenal axis activated by drugs, repeated use dysregulates activity and feedback loop.
Modern stress
Don’t need fight or flight anymore. Modern stress is prolonged not acute. The burst of energy is counterproductive.
Stress as a risk factor
All ACEs increase use, maybe due to stress. Stress predicts use, both ever or frequency. Stress reactivity is also key, differences predict vulnerability. Rats use prolonged corticosterone responses have faster acquisition of self admin also increased amount of drug used.
Mechanisms
Hypothalamus releases corticotropin-releasing factor (CRF) activates pituitary which releases adrenocorticotropic hormone (ACTH) activated the adrenal cortex which releases cortisol. Feedback function, cortisol binds to hypothalamus and pituitary receptors to stop production to avoid overstress.
Early life stress and stress systems
Longitudinal, low baseline corticol in women with early life adversity. Similar corticol release seen in primates and alcoholics/ their families. May be genetic or shared environment.
McArthur (2005)
Modelled stress exposure in rats. Exposed pre and post natally to glucocortical measured effect on dopamine cells in VTA and limbic system. Exposure increased number of dopamine neurons in VTA by 50% and increased sensitivity of reward system suggesting increased drug response.
Stress and CYP enzymes
Most drugs metabolised by cytochrome P450 enzymes in liver. Different CYPs for different drugs. Stress impacts synthesis of CYP enzymes changing metabolism of drugs.
Stress and abstinence
Key stress systems are dysregulated by chronic use, neurochemical changes during acute abstinence include increased adrenocorticotropic hormones increased corticosterone and CRF. Role in maintenance of drug use as self med. Target for intervention.
Targeting use via stress
CRF-1 antagonists decrease self administration. Lower abstinence related anxiety across drugs if medically lower CRF drug use falls even in addicts.
Stress addiction and transition.
Shift from reward to anti-reward. Impulsivity to compulsivity. Cycle of lowered function of reward systems and recruitment of anti-reward systems.
Neuroadaptations of reward systems
Recruit stress systems due to withdrawal, negative effects and anxiety. Activated in drug use and dysregulated when chronic. Anticipation causes drug use, reward and, positive reinforcement. Purely positive. Stress systems activated by abstinence and switch to anti-reward and negative reinforcement.
