For example, addiction to sedative drugs often causes dysarthria, ataxia, and slowed thinking and movement. Amphetamines, however, often lead to nervousness, agitation, tremor, delirium, panic states, and extreme fatigue. The extent of limitation is usually more severe with longer period of addiction and with increased dosages. Also, withdrawal symptoms often create a different set of functional limitations from those associated with the effects of the drug itself. Cognitive impairments, such as decreased memory or attention, are also common.
Substance abuse can occur at any age, and it is a chronic disorder unless treated.
In severe cases, it can lead to death.