duration may occur in one-third or more, and there is some evidence that these substances
may also be associated with persistent mild  NCD. Major NCD associated with these sub-
stances is rare, if it occurs at  all. In the case of methamph etamine, cerebr ovascular disease
can also occur, resulting in diffuse or focal brain injury that  can be of mild or major neu-
rocognitive levels. Solvent expo sure has been linked to both major and mild NCD of both
intermediate and persistent duration. 
The presence of NCD induced by cannabis and various hallucinogens is controversial.
With cannabis, intoxication is  accompanied by various neur ocognitive disturbances, but
these tend to clear with abstinence.