Lecture 4: Drugs and the Developing Brain

Tolerance

Reduction in the effect of a drug as a result of repeated use, requiring users to consume greater quantities to achieve the same effect

Withdrawal

Unpleasant effects of reducing or stopping consumption of a drug that users had consumed a lot of

Physical dependence

Dependence on a drug that occurs when people continue to take it to avoid withdrawal symptoms

Psychological dependence

Continued use of drug that is motivated by intense cravings

Hypnotic

Drug that exerts a sleep-inducing effect

What drug is categorised as a depressant?

Alcohol (and sedative hypnotics)

Why is alcohol classed as a ‘depressant’?

Because it behaves as an emotional and physiological stimulant only at relatively low doses because it depresses areas of the brain that inhibit emotion and behaviour

Stimulant

Drugs that increase activity in the central nervous system (CNS) including heart rate, respiration, and blood pressure.

What neurotransmitters does cocaine increase the activity of?

Dopamine

Narcotic

Drug that relives pain and induces sleep (e.g. opioid drugs such as heroin, morphine, and codeine)

Hallucinogenic

Causing dramatic alternations of perception, mood, and thought (e.g. marijuana)

Psychoactive drugs

Substance that contains chemicals similar to those found naturally in our brains that alter consciousness by changing chemical processes in neurons.

Pituitary Gland

Produces and releases hormones that regulate the activity of other endocrine glands in the body

Teratogens

Chemicals or factors that have potential to damage the fetus when exposure occurs during pregnancy (alcohol, radiation, thalidomide).

When timing and dose are below the teratogenic threshold..

Some exposures have little risk of causing malformation

The degree of damage on the fetus depends on..

The timing (i.e. the trimester) and dose of exposure

Fetal Alchohol Spectrum Disorder (FASD)

Permanent birth defect due to maternal alcohol use during pregnancy

Triad symptoms of FASD

Growth deficiency, facial abnormalities, organic brain damage

What causes facial abnormalities in children?

Exposure to alcohol in the 1st trimester will cause a higher chance of facial abnormalities due to facial features being developed by facial features being developed in the first trimester.

What does maternal ongoing stress lead to in offspring?

Offspring faced with emotional/behavioural/cognitive problems (like anxiety, ADHD, language delay, conduct issues)

How do chronic high levels of cortisol affect brain development?

Leads to a long-lasting/prolonged state of over activation meaning that children develop a low threshold for stress

How does stress affect learning?

Reduces the growth of the hippocampus which impairs learning

Crucial period of offsprings’ life

Prenatal to the age of 3

Why is addiction a problem for individuals in treatment?

• 25% have PTSD - Past trauma including sexual and physical abuse

• Parents have also used substances

• Deprived backgrounds where essential resources and support is lacking

• Traumatic (adverse) experiences

• 40% have co-occurring mental illness, complicating their treatment process.

Parent’s substance abuse on children aged 6-51 can cause

Mental health problems, disrupted school experience, trouble with the law, inappropriate sexual behaviour, confinement, alcohol & drug problems

Parent’s substance abuse on offspring aged 21-51 can lead to

Dependent Living, problems with Employment

Problems associated with teenage drinking

Depression, suicide, more likely to have issues with violence, more likely to be engaged with the legal system, more likely to have an impact on educational performance

The hippocampus when teenagers have had a drink

10% smaller, which means there will be problems with storing new information as memories

Name 2 effects of alcohol on the teenage brain

1. Alcohol interferes with storing new information as memories

2. Alcohol use interrupts normal brain “wiring” by slowing down brain activity and development

The most important part of the brain

The frontal lobe

Frontal lobe

Involved in thought and voluntary behaviour (memory, abstract thinking, goal formation, planning, impulse control)

The brain at age 10+

Most brain changes serve to improve function of the more sophisticated and versatile frontal lobe

The brain at age 17

Brain goes through second growth spurt when the frontal lobe increases in size again, as do their synaptic connections to the rest of the brain.

The brain by age 18

Periodic pruning where brain sheds unnecessary connections

The use of cannabis has clear associations with

Increased risk of dependence, increased risk of other drug abuse, poor education outcome (cognition, IQ), poor mental health (psychosis, anxiety), poor physical health (respiratory disease, cancer)

Environmental condition is a

confounding effect on brain development

The most prevalent teratogens is

Cigarette smoking during pregnancy