The contention that methylphenidate acts as a gateway drug has been discredited by multiple sources, according to which abuse is statistically very low and "stimulant therapy in childhood does not increase the risk for subsequent drug and alcohol abuse disorders later in life". A study found that ADHD medication was not associated with increased risk of cigarette use, and in fact stimulant treatments such as Ritalin seemed to lower this risk. People treated with stimulants such as methylphenidate during childhood were less likely to have substance use disorders in adulthood.Among countries with the highest rates of use of methylphenidate medication is Iceland, where research shows that the drug was the most commonly used substance among people who inject drugs. The study involved 108 people who inject drugs and 88% of them had injected methylphenidate within the last 30 days and for 63% of them, methylphenidate was the most preferred substance. Treatment of ADHD by way of methylphenidate has led to legal actions, including malpractice suits regarding informed consent, inadequate information on side effects, misdiagnosis, and coercive use of medications by school systems. Research
Methylphenidate may have benefit as a treatment of apathy in patients with Alzheimers disease. It may be useful in losing weight.Methylphenidate may provide possible protection from methamphetamine-induced dopamine neuron damage and possible protection from Parkinsons disease.Methylphenidate has been studied in the treatment of Parkinsons disease. Replacement therapy
Methylphenidate has shown some benefits as a replacement therapy for individuals who are addicted to and dependent upon methamphetamine.
There is weak evidence in favor of methylphenidates effectiveness for depression, including providing additional benefit in combination with antidepressants. In individuals with terminal cancer, methylphenidate can be used to counteract opioid-induced somnolence, to increase the analgesic effects of opioids, to treat depression, and to improve cognitive function. A 2021 systematic review and meta-analysis found that all studies on geriatric depression reported positive results of methylphenidate use; the review recommended short-term use in combination with citalopram. A 2018 review found low quality evidence supporting its use to treat apathy as seen in Alzheimers Disease in addition to slight benefits for cognition and cognitive performance. Enhancing performance
A 2015 review found that therapeutic doses of amphetamine and methylphenidate result in modest improvements in cognition, including working memory, episodic memory, and inhibitory control, in normal healthy adults; the cognition-enhancing effects of these drugs are known to occur through the indirect activation of both dopamine receptor D1 and adrenoceptor α2 in the prefrontal cortex. Methylphenidate and other ADHD stimulants also improve task saliency and increase arousal. Stimulants such as amphetamine and methylphenidate can improve performance on difficult and boring tasks, and are used by some students as a study and test-taking aid. Based upon studies of self-reported illicit stimulant use, performance-enhancing use rather than use as a recreational drug, is the primary reason that students use stimulants.Excessive doses of methylphenidate, above the therapeutic range, can interfere with working memory and cognitive control.