Substance Use Disorders

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Introduction

Abuse is reckless use, while dependence is loss of control.

It can be helpful to consider substance use disorders as a chronic and relapsing illness. Prevention is possible, and if properly managed, they can lead a normal life. Multiple treatment strategies are helpful and important.

If a person is diagnosed with asthma, they have a 50% likelihood of presenting for emergency care. (McLellan et al, 1999). Similar rates are seen for addictions.

Substance abuse is a maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by one or more of the following, occurring within one year:

recurrent use in hazardous circumstances
failure in obligations at work, school, or home
legal issues related to recurrent use
despite problems with social or interpersonal relationships

Substance dependence is a maladaptive pattern of substance use leading to clinically significant impairment or distress, as maifested by three or more of the following, occurring within one year:

withdrawal
amount: substance is taken in larger amount, or with greater frequency, than intended
social, occupational, or recreational activities are given up or reduced
tolerance: need for markedly increased amounts, or markedly decreased effects with continued use
much time spent obtaining, using, or recovering from substance use
persistent efforts to cut down or control substance use
despite problems with social/interpersonal relationships, or psychological/physical issues

Addiction

a combination of physical and psychological dependence
involves psychosocial factors
continued drug seeking despite knowledge of harmful effects
behaviour becomes a preoccupation and detriment

The Case of...

a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.

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Causes and Risk Factors

Various drugs of abuse or dependence

Substance Induced Disorders

intoxication, withdrawal, delerium, mood, anxiety psychotic disorders,

Club Drugs

Raves ave been around for 10-15 years. Has to do with subcultures. By 2000, raves become harder, with increased aggression, more poly drugs, more individualistic and hedonistic. are club drugs non-deviant drug use?

Emergency Management of Substance Use

If you know someone has taken something, there is a set management plan:

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Pathophysiology

Much of our understanding has been derived from behaviourally contingent drug self-administration, whereby animals learn to perform a certain action, eg pressing a lever, to receive a dose a drug. This model allowed for different experimental conditions or biological interventions to study changes in behaviour.

The acute reward pathway is within the mesolimbic system, primarily using dopamine as a neurotransmitter. Projections leave the ventral tegmental area, located within the brainstem, and project to the nucleus accumbens, with projections to the limbic system. Signals end within the prefrontal contex.

The amygdala

Neural placticity is critical during addiction Important target genes include proenkephalin, prodynorphin, c-fos, CREB, and others.

The body tries to manitain homeostasis. With repeated use of a drug, chronic changes occur to modulate the biological effect.

The animal model has shown a biological role for many of the risks of relapse:

stress, eg noise, lack of sleep
environmental cues, eg a red light in rats, a place
other reward drugs, eg nicotine, heroin
amygdala stimulation

Genetic polymorphisms that influence severity of substance dependence, in concert with environmental factors:

opioid receptor genes

opioids
cocaine
amphetamines
alcohol

Opioids

Acute effects include:

Long term changes include:

decreased dendritic branching within VTA dopamine cells (Nestler and Agahjanian, Science)

Long-term changes in remission include:

elevated metabolism in the anterior cingulate gyrus (may be reversed by methadone maintenance)

These permanent changes in gene expression and brain function suggest opioid remission may be a life-long struggle.

Cocaine

Acute effects include:

Long term changes include:

decrease cortical signaling

Amphetamines and Methamphetamines

Acute effects include:

Long term changes include:

increased activity in the anterior and posterior cingulate gyri
decreased prefrontal cortex function; impaired
- concentration, attention
- jugement and decision-making
slow reversal of brain function.