Psychoactive SubstanceUse and Dependence“Addiction (DSM5)”

By

Soheir H. ElGhonemy Assist. Professor of Psychiatry- Ain Shams University- Egypt

Member of International Society of Addiction MedicineMember of European and American Psychiatric Associations

Trainer Approved by NCFLDselghonamy@hotmail.com

Mechanisms relating psychoactive substance use to healthand social problems

Summary of psychoactive substance effects:

Substance

Primary mechanism of

action

Tolerance and withdrawal Prolonged use

Ethanol Increases the inhibitory effects of GABA and decreases the excitatory effects of glutamate. Reinforcing effectsprobably related toincreased activity in mesolimbic dopamine pathway.

Tolerance develops due to increased metabolism in the liver, and changes to receptors in the brain. Withdrawal from chronic use can include shaking, perspiration, weakness, agitation, headache, nausea,vomiting, seizures,delirium tremens.

Altered brain function and structure, particularly in prefrontal cortex;cognitive impairments;decreased brain volume.

Substance

Primary mechanism of

action

Tolerance and withdrawal Prolonged use

Hypnoticsandsedatives

Facilitate the actions of endogenous inhibitory neurotransmitters.

Tolerance developsrapidly to most effects (except anti- convulsant),due to changes in brain receptors.Withdrawal characterized by anxiety, arousal,restlessness, insomnia, excitability, seizures.

Memory impairment.

Substance

Primary mechanism of

action

Tolerance and withdrawal Prolonged use

Nicotine Activates nicotinicCholinergic receptors.Increases dopaminesynthesis and release.

Tolerance developsthrough metabolicfactors, as well asreceptor changes.Withdrawal characterizedby irritability, hostility,anxiety, dysphoria,depressed mood,decreased heart rate,increased appetite.

Health effects dueto smoking are well documented;difficult todissociate effects ofnicotine from othercomponents of tobacco.

Substance

Primary mechanism of

action

Tolerance and withdrawal Prolonged use

Opioids Activates receptorscalled mu and delta opioid receptors. These receptors are abundant in brain areas involved in responses to psychoactivesubstances, such as in the mesolimbicDopamine pathway.

Tolerance occurs due to short-term and long-term receptor changes, and adaptations in intracellular signallingmechanisms.Withdrawal can be severe and is characterizedby watering eyes,runny nose, yawning,sweating, restlessness, chills, cramps, muscle aches.

Long-term changes in opioid receptors and peptides; adaptationsin reward, learning,stress responses.

SubstancePrimary

mechanism of action

Tolerance and withdrawal Prolonged use

Cannabinoid Activates cannabinoidreceptors. Also increases dopamine activity in the mesolimbicpathway.

Tolerance developsrapidly to most effects.Withdrawal is rare,perhaps due to long halflifeof cannabinoids.

Long-term exposure tocannabis may producelong-lasting cognitiveimpairment. Risk ofexacerbation of mentalillness is also present..

SubstancePrimary

mechanism of action

Tolerance and withdrawal Prolonged use

Cocaine Cocaine blocks the uptake of transmitters such as dopamine,thereby prolongingits effects.

Perhaps short-term acute tolerance occurs. There isnot much evidenceof withdrawal, however, depression is common among dependentpersons who stop using the drug

Cognitive deficits,abnormalities in specific regions of the cortex,impairments in motor function, and decreasedreaction times have been found.

SubstancePrimary

mechanism of action

Tolerance and withdrawal Prolonged use

Amphetamines

Increases release of dopamine from nerve terminals and inhibitsthe reuptake ofdopamine andRelated transmitters.

Tolerance developsrapidly to behavioral andphysiological effects. Withdrawal is characterizedby fatigue, depression, anxiety and intense craving for the drug.

Sleep disturbances,anxiety, decreasedappetite; alterations inbrain dopamine receptors, regional metabolic changes, motor and cognitive impairments

SubstancePrimary

mechanism of action

Tolerance and withdrawal Prolonged use

Ecstasy Increased serotonin release and blockadeof reuptake.

Tolerance may develop in some individuals. Most common withdrawalsymptoms aredepression andinsomnia.

Damages brain serotonin systems, leads to behavioral andphysiological consequences.Long-termpsychiatric and physical problems such as impairmentsof memory, decision- making and self-control,paranoia,depression and panic attacks

SubstancePrimary

mechanism of action

Tolerance and withdrawal Prolonged use

Inhalants Most likely affectsInhibitory transmitters,similarly to othersedatives and hypnotics. Mesolimbic dopamine activated.

Some tolerancedevelops, but is difficult to estimate. There is increased susceptibility to seizures duringwithdrawal.

Changes in dopaminereceptor bindingand function; decreasedCognitive function;psychiatric andneurological problems.

SubstancePrimary

mechanism of action

Tolerance and withdrawal Prolonged use

Hallucinogens Different substances inthis class act on differentbrain receptors, such asserotonin, glutamate, andacetylcholine receptors.

Tolerance developsrapidly to physical andpsychological effects. There is no evidence of withdrawal.

Acute or chronic psychotic episodes, flashbacks or Re-experiencing of substance effects longafter substance use.

Circuits Involved In Drug Abuse and Addiction

All of these must be consideredin developing strategies to effectively treat addiction

Reward System

Schick Shadel Hospital, 2009

Drugs

Brain Mechanisms

Behavior

Environment

Historical

Environmental

- Prior experience- Expectation- Learning

- Social interactions- Stress- Conditioned stimuli

- Genetics- Circadian rhythms- Disease states- Gender

Physiological

Drug Addiction: A Complex Behavioral and Neurobiological

Disorder

Treating a Bio-behavioral Disorder Must Go Beyond JustFixing the Chemistry

1. Pharmacological (medications)2. Behavioral Therapies3. Medical and Social Services4. Family Services

SUCCESSFUL RECOVERY FROM ADDICTIONS

Occurs over long periods of time Often involves multiple attempts

and treatments Consists of self change and/or

treatment Involves changes in other areas of

psychosocial functioning