Addiction is a serious risk with heavy recreational amphetamine use, but is unlikely to occur from long-term medical use at therapeutic doses. Very high doses can result in psychosis (e.g., delusions and paranoia) which rarely occurs at therapeutic doses even during long-term use. Recreational doses are generally much larger than prescribed therapeutic doses and carry a far greater risk of serious side effects.Amphetamine belongs to the phenethylamine class. It is also the parent compound of its own structural class, the substituted amphetamines, which includes prominent substances such as bupropion, cathinone, MDMA, and methamphetamine. As a member of the phenethylamine class, amphetamine is also chemically related to the naturally occurring trace amine neuromodulators, specifically phenethylamine and N-methylphenethylamine, both of which are produced within the human body. Phenethylamine is the parent compound of amphetamine, while N-methylphenethylamine is a positional isomer of amphetamine that differs only in the placement of the methyl group. Uses
Medical
Amphetamine is used to treat attention deficit hyperactivity disorder (ADHD), narcolepsy (a sleep disorder), and obesity, and is sometimes prescribed off-label for its past medical indications, particularly for depression and chronic pain. Long-term amphetamine exposure at sufficiently high doses in some animal species is known to produce abnormal dopamine system development or nerve damage, but in humans with ADHD, pharmaceutical amphetamines at therapeutic dosages appear to improve brain development and nerve growth.
Physical factors
The development of paranoia and hallucinations in old age have been related to both auditory and visual impairment, and individuals with paraphrenia often present with one or both of these impairments. Hearing loss in paraphrenics is associated with early age of onset, long duration, and profound auditory loss. History
The term paraphrenia was originally popularized by Karl Ludwig Kahlbaum in 1863 to describe the tendency of certain psychiatric disorders to occur during certain  transitional periods in life (describing paraphrenia hebetica as the insanity of the adolescence and paraphrenia senilis as the insanity of the elders.The term was also used by Sigmund Freud for a short time starting in 1911 as an alternative to the terms schizophrenia and dementia praecox, which in his estimation did not correctly identify the underlying condition, and by Emil Kraepelin in 1912/3, who changed its meaning to describe paraphrenia as it is understood today, as a small group of individuals that have many of the symptoms of schizophrenia with a lack of deterioration and thought disorder. Kraepelins study was discredited by Wilhelm Mayer in 1921 when he conducted a follow-up study using Kraepelins data. His study suggested that there was little to no discrimination between schizophrenia and paraphrenia; given enough time, patients presenting with paraphrenia will merge into the schizophrenic pool. However, Meyers data are open to various interpretations. In 1952, Roth and Morrissey conducted a large study in which they surveyed the mental hospital admissions of older patients.