Drug dependence and substance abuse

Fifth stage

Psychiatry
Lec-23
د. الهام

23/4/2017

Developmental Disease

Addiction is a Developmental Disease: It Starts Early

Basic Science Tells Us that Adolescents’ Brains Are Still Developing…

When Reading Emotion…Adults Rely More on the Frontal Cortex, While Teens Rely More on the Amygdala
Do Adolescents React Differently than Adults to Substances of Abuse?

Rats Exposed to Nicotine in Adolescence Self-Administer More Nicotine Than Rats First Exposed as Adults

Do We Need FundamentallyDifferent Strategies AtDifferent Stages of Adolescence?

Americans’ Views of the Seriousnessof Health Problems(Top 10 of 36 Problems)

Definitions:

Drug Use
Taking a psychoactive substance for non-medical purposes, out of curiosity
Drug Abuse
Drug use that leads to problems (e.g. loss of effectiveness in society; behavioral psychopathology, criminal acts)
Drug Dependence
A maladaptive pattern of drug use leading to clinically-significant impairment or distress, associated with difficulty in controlling drug-taking behavior, withdrawal, and tolerance
The state of needing a drug to function within ‘normal limits’

Nature of Addiction - a continuum of use?

However, addiction is more than mere drug use…

DSM-IV Criteria for Substance Dependence:
A maladaptive pattern of substance use, leading to clinically significant impairment or distress, as manifested by three (or more) of the following, occurring at any time in the same 12 month period:
Tolerance
Withdrawal
Substance taken in larger amounts or over a longer period than intended
Persistent desire or unsuccessful efforts to cut down or control substance use
Great deal of time spent in activities necessary to obtain substance, use substance (e.g., chain smoking), or recover from effects
Important social, occupational, or recreational activities given up or reduced because of substance use
Substance use continued despite knowledge of persistent or recurrent physical or psychological problem likely to have been caused or exacerbated by substance



Addiction Involves Multiple Factors:

Physical vs. Psychological Dependence:

Physical Dependence
Withdrawal symptoms in the absence of the drug
Tolerance to its effects with repeated use
Psychological Dependence
“a relatively extreme, pathological state in which obtaining, taking, and recovering from a drug represents a loss of behavioral control over drug taking which occurs at the expense of most other activities and despite adverse consequences” (Altman et al)
“a situation where drug procurement and administration appear to govern the organism’s behavior, and where the drug seems to dominate the organism’s motivational hierarchy” (Bozarth)


Physical Dependence or Withdrawal Model(Negative Reinforcement):
Some drugs produce physical dependence and withdrawal symptoms upon cessation of drug-taking.
Withdrawal symptoms are produced by the body in order to compensate for the unusual effects of the drug.
Withdrawal symptoms are generally the opposite of the effect produced by the drug.
Addicts continue to use drugs in order to avoid withdrawal.
Over time, drugs no longer have the same rewarding effects - they merely allow the person to feel “normal.”

Positive Incentive (Hedonic) Models(Positive Reinforcement):

Drugs produce pleasure - a “high.”
Some drugs provide indirect positive incentive - they disinhibit behavior that is normally suppressed (e.g., alcohol and social skills).
Most drugs of abuse stimulate the brain’s reward circuits.
All known drugs of abuse stimulate release of DA/opioids in the nucleus accumbens
Animals will work to micro-inject drugs of abuse and electrically stimulate the same parts of the brain
Normal rewards (food, drink, sex) also stimulate DA release

Drug Dependence Among Ever-Users:

Why do Mental Illnesses and Substance Abuse Co-occur?

Self-medication hypothesis
substance abuse begins as a means to alleviate symptoms of mental illness
Causal effects of substance abuse
Substance abuse may increase vulnerability to mental illness
Common or correlated causes
the life processes and risk factors that give rise to mental illness and substance abuse may be related or overlap


Why Do People Take Drugs in The First Place?

Why Can’t Addicts Just Quit?

Treating a Biobehavioral Disorder Must Go Beyond Just Fixing the Chemistry

But, drug addiction is a chronic illness with relapse rates similar to those of hypertension, diabetes, and asthma

Drug Use Has Played a Prominent Role in the HIV/AIDS EpidemicIn Several Ways:

Disease Transmission
IV Drug Use
Drug User Disinhibition Leading to High Risk Sexual Behaviors
Progression of Disease