Walkner, Renee
Physiological Comp.
April 20, 2011
CNS Stimulants
“Stimulants (also called psychostimulants [1]
) are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others. Due to their effects typically having an "up" quality to them, stimulants are also occasionally referred to as "uppers". Depressants or "downers", which decrease mental and/or physical function, are in stark contrast to stimulants and are considered to be their functional opposites. Stimulants are widely used throughout the world as prescription medicines and as illicit substances of recreational use or abuse.”
(http://en.wikipedia.org/wiki/Stimulant) Stimulants are known by different names:
 Common, illicit, prescription and OTC (over-the-counter) stimulants are known as: caffeine, nicotine, amphetamines, methamphetamines, MDMA (ecstasy), cocaine, methylphenidate, Modafinil, Adrafinil, Armodafinil, Ampakines and
Yohimbine.
 “Street” names: amphetamine (“street” names Bennies, Dexies, Benzedrine); methamphetamine (street names: Ice, Meth, Crystal); and amphetamine (street names: Bennies, Dexies, Benzedrine); methamphetamine (street names: Ice,
Meth, Crystal); and methcathinone (street name: CAT).

Walkner, Renee
Physiological Comp.
April 20, 2011
All drugs of abuse act in the brain to produce their euphoric effects; however some of them also have severe negative consequences in the brain such as seizures, stroke, and widespread brain damage that can impact all aspects of daily life. Drug use can also cause brain changes that lead to problems with memory, attention and decision-making.
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Drugs that can cause neurological problems:
 Cocaine
GHB
Inhalants
Marijuana
MDMA
Methamphetamine
Nicotine
Prescription Stimulants
Rohypnol
Neurological effects: Progressive myelination during adolescence implicates an increased vulnerability to neurotoxic substances and enduring neurocognitive consequences. This study conducted by Dr. Bava and colleagues examined the cognitive

Walkner, Renee
Physiological Comp.
April 20, 2011 manifestations of altered white matter microstructure in chronic marijuana and alcoholusing (MJ+ALC) adolescents. Thirty-six MJ+ALC adolescents (ages 16-19) and 36 demographically similar controls were evaluated with diffusion tensor imaging and neurocognitive tests. Regions of group difference in fractional anisotropy (FA) and mean diffusivity (MD) were analyzed in relation to cognitive performance. In users, lower FA in temporal areas related to poorer performance on attention, working memory, and speeded processing tasks. Among regions where users had higher FA than controls, occipital FA was positively associated with working memory and complex visuomotor sequencing, whereas FA in anterior regions was negatively associated with verbal memory performance. Findings suggest differential influences of white matter development on cognition in MJ+ALC using adolescents than in non-using peers.
Neuroadaptation may reflect additive and subtractive responses to substance use that are complicated by competing maturational processes. (Bava S, Jacobus J, Mahmood O,
Yang TT, Tapert SF. Neurocognitive correlates of white matter quality in adolescent substance users. Brain Cogn. 2010 Apr;72(3): 347-354).
Physiological effects of drug abuse vary by the type of drug. Stimulants, such as amphetamines, can delay sleep and elevate a person's mood, but high amounts can cause nervousness and anxiety in the user. Depressants, by contrast, impair mental and physical functions, and slow neural activity in the brain.
With some drugs, especially narcotics such as opium or heroin, the body can build a tolerance in which it adjusts to the drug's presence. Over time, the body requires higher doses to maintain the same effect. When an abuser stops taking the drug, the body

Walkner, Renee
Physiological Comp.
April 20, 2011 experiences withdrawal symptoms, such as feeling weak or sick. Withdrawal symptoms are the body's reaction to the absence of the drug to which it had become adjusted.
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By increasing levels of dopamine and adrenaline / noradrenaline , stimulants increase endurance and subjective strength, meaning that the person does not feel like he is exerting as much effort despite higher performance. However, stimulants do not increase objective performance- ultimately the feelings of increased strength and endurance are just due to increased energy.
Some stimulants, such as methamphetamine and cocaine, produce varying degrees of euphoric sensations, mediated by an increase in extra-cellular dopamine levels in the ventral striatum [1] . Together with norepinephrine, these stimulants increase pain tolerance,
[4]
which allows the user to continue using muscles that would ordinarily be sending crippling messages of pain - the muscle may not be stronger, but working them to failure becomes easier. The nervous system effects also cause an increased ability to concentrate, and a focus on continuing a workout, exercise, or feat of strength past usual thresholds of pain becomes far easier as well. In addition, the stimulant effects increase metabolism and motor activity, which makes more energy available to muscles and permit greater endurance and longer workouts. Taken together, these effects can easily cause complications, some life-threatening. It is also important to keep in mind that studies have proven weightlifting shows better results with rests between sets, so regardless of pharmaceutical fatigue suppression this should be observed.
[5]

Walkner, Renee
Physiological Comp.
April 20, 2011
[ edit ] Health risks
An important risk associated with stimulants is that decreased pain feedback allows users to easily push the muscle past the point of capable regrowth to the point of serious damage, possibly resulting in torn muscles.
More seriously, the euphoric effects of most stimulants can block adequate pain feedback in conditions that place high stress on the whole body - hyperthermia , the condition that causes heatstroke, is a prominent example of this. The increase in metabolism due to the stimulant's effects increases the amount of heat the body produces, possibly aggravating the condition. The euphoric effects of the drug often then mask warning signs of organ failure until serious complications, or even death, occurs.
Signs and symptoms: A fever is usually accompanied by sickness behavior, which consists of lethargy, depression, anorexia, sleepiness, hyperalgesia , and the inability to concentrate.

Walkner, Renee
Physiological Comp.
April 20, 2011
References:
1. http://en.wikipedia.org/wiki/Stimulant
2. http://www.saps.gov.za/drugs/ats.htm
3. http://www.drugabuse.gov/consequences/neurological/
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Bava S, Jacobus J, Mahmood O, Yang TT, Tapert SF. Neurocognitive correlates of white matter quality in adolescent substance users. Brain Cogn. 2010 Apr;72(3): 347-354