Substance-Induced
Psychotic Disorder Like with general medical illness induced psychotic
disorders substances such as alcohol, illicit drugs, but also medications can
lead to psychotic disorders. Moreover, on withdrawal of some substances psychosis
can also occur. For instance, when a patient is an alcoholic and is used
to regular intake of a high percentage alcoholic beverage such as whiskey and
this patient is suddenly stopping to drink and withdrawal occurs, there often
will be a full-blown withdrawal psychosis (delirium
tremens) within 48 hours. Typically the auditory hallucinations consist of voices,
but there often are also visual hallucinations and tactile hallucinations such
as bugs crawling over the bed sheet and on the skin.
In
intoxication psychosis such as with amphetamine or cocaine
intoxication similar hallucinations and delusions occur. In this setting persecutory
delusions may develop shortly after using amphetamines or cocaine(see Ref.2).
There may be a distortion of the body image when looking in a mirror, or
peoples faces are being misinterpreted as the brain makes connections where there
aren't any. The patient also may have tactile hallucinations "feeling"
imaginary bugs underneath the skin and scratching the skin to the point of injury.
With cannabis psychosis does not develop that frequently, but when it does, it
does so early on with the development of marked anxiety, frequent mood changes
and persecutory delusions. After the episode there often is no memory of it(amnesia).
The higher he blood levels of cannabis are the more likely hallucinations occur.
When amphetamine or cocaine use has been stopped after the occurrence of
a psychosis, the psychosis may not stop the way the patient and he physician had
hoped for. Sometimes these psychotic states can last weeks or even months past
the point where drug use was stopped, even when the patients are treated with
antipsychotic medication. The reason may be that there can be toxic changes of
the brain receptors and changes in the brain metabolism that take time to repair(see
Ref. 4). Some regular medications such as anesthetics used for surgeries,
anti seizure medications, antihypertensives, antihistamines, antibiotics, corticosteroids,
non steroidal anti-inflammatory medications, muscle relaxants and even over-the-counter
cold remedies like phenylephrine or pseudoephedrine can all lead to psychotic
symptoms. It
is not known what makes some patients more susceptible than others, but factors
that have been identified are differences in enzymatic elimination rates in liver
and kidneys leading to fluctuating blood levels. In some patients very high levels
lead to psychosis. Other patients at risk are older patients, particularly above
75 years of age, where the elimination of medications is hampered due to a much
reduced kidney function as well as a slower metabolism. Often medications have
to be reduced and drug companies often offer medication with reduced dosages for
older patients. Drug interactions are another factor, if the patient is taking
several medications for different organ systems. For many medications or
toxic substances the same set of detoxifying enzymes are needed in the liver to
eliminate them from the blood stream. This creates an overload situation and toxic
blood levels causing psychosis can result. You may have read warnings about using
the over-the-counter antihistamine Seldane when the patient is also on erythromycin
for an infection. Each of these used separately alone are harmless, but when taken
together they can cause serious harm. Some of the medications such as antiepileptic
drugs or theophylline levels for asthmatics, which also have this interaction
in the liver, can be monitored through serial blood level determinations. This
avoids toxic levels in cases where both these medications have to be taken together.
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