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How Meth Destroys The Body | The Meth Epidemic | FRONTLINE | PBS

"There [are] a whole variety of reasons to try methamphetamine," explains Dr. Richard Rawson, associate director of UCLA's Integrated Substance Abuse Programs. "[H]owever, once they take the drug … their reasons are pretty much the same: They like how it affects their brain[s]." Meth users have described this feeling as a sudden rush of pleasure lasting for several minutes, followed by a euphoric high that lasts between six and 12 hours, and it is the result of drug causing the brain to release excessive amounts of the chemical dopamine, a neurotransmitter that controls pleasure. All drugs of abuse cause the release of dopamine, even alcohol and nicotine, explains Rawson, "[But] methamphetamine produces the mother of all dopamine releases." For example, in lab experiments done on animals, sex causes dopamine levels to jump from 100 to 200 units, and cocaine causes them to spike to 350 units. "[With] methamphetamine you get a release from the base level to about 1,250 units, something that's about 12 times as much of a release of dopamine as you get from food and sex and other pleasurable activities," Rawson says. "This really doesn't occur from any normally rewarding activity. That's one of the reasons why people, when they take methamphetamine, report having this euphoric [feeling] that's unlike anything they've ever experienced." Then, when the drug wears off, users experience profound depression and feel the need to keep taking the drug to avoid the crash.

Cognitive dysfunction in major depression and bipolar disorder: Assessment and treatment options - MacQueen - 2016 - Psychiatry and Clinical Neurosciences - Wiley Online Library

Exercise may have positive effects on cognition in healthy people and is being investigated as a possible strategy for maintaining cognitive function throughout aging. It also improves symptoms of depression.[76-79] The degree to which it actually improves cognitive function in those with a mood disorder is not well known.[80] High-dose exercise was associated with improvement in spatial working memory while other cognitive domains, including attention, visual memory, and spatial planning, improved regardless of dose in one study.[81] Another study included a subset of patients with BD (3/12, while the other participants had schizophrenia) and found that intense circuit training was associated with improvement in memory and processing speed; depressive symptoms also improved.[82] There are therefore a variety of factors that require investigation to understand how to maximize the benefits of exercise on cognition in patients with mood disorders. These include better understanding of the individual variability in response to training, optimal dosing or training schedules, the synergistic effects of exercise in combination with other interventions[83] and the actual mechanisms through which exercise works on the neural circuits that are disrupted in depression.

Adderall Concentration Benefits in Doubt: New Study

The last question they asked their subjects was: "How and how much did the pill influence your performance on today's tests?" Those subjects who had been given Adderall were significantly more likely to report that the pill had caused them to do a better job on the tasks they'd been given, even though their performance did not show an improvement over that of those who had taken the placebo.

Differential effects of acute and regular physical exercise on cognition and affect. - PubMed - NCBI

Participants were evaluated on novel object recognition (NOR) memory and a battery of mental health surveys before and after engaging in either (a) a 4-week exercise program, with exercise on the final test day, (b) a 4-week exercise program, without exercise on the final test day, (c) a single bout of exercise on the final test day, or (d) remaining sedentary between test days. Exercise enhanced object recognition memory and produced a beneficial decrease in perceived stress, but only in participants who exercised for 4 weeks including the final day of testing. In contrast, a single bout of exercise did not affect recognition memory and resulted in increased perceived stress levels.