LITHIUM, MOOD STABILIZING DRUGS, & OTHER TREATMENT FOR
BIPOLAR DISORDER
Bipolar disorder, once
known as manic-depressive illness, was conceived of as a psychotic disorder
distinct from schizophrenia at the end of the 19th century. Before that both of
these disorders were considered part of a continuum. It is ironic that the
weight of the evidence today is that there is profound overlap in these
disorders. This is not to say that there are no pathophysiologically important
differences or that some drug treatments are differen-tially effective in these
disorders. According to DSM-IV, they
are separate disease entities while research continues to define the dimensions
of these illnesses and their genetic and other biologic markers.Lithium was the
first agent shown to be useful in the treatment of the manic phase of bipolar
disorder that was not also an anti-psychotic drug. Lithium has no known use in
schizophrenia. Lithium continues to be used for acute-phase illness as well as
for prevention of recurrent manic and depressive episodes.
A group of
mood-stabilizing drugs that are also anticonvulsant agents has become more
widely used than lithium. It includes carbamazepine
and valproic acid for the
treatment of acutemania and for prevention of its recurrence. Lamotrigine is approved for prevention
of recurrence. Gabapentin,
oxcarba-zepine, and topiramate are
sometimes used to treat bipolar disor-der but are not approved by the Food and
Drug Administration for this indication. Aripiprazole,
chlorpromazine, olanzapine,quetiapine, risperidone, and ziprasidone are approved by theFDA for treatment of the manic
phase of bipolar disorder. Olanzapine plus fluoxetine in combination and
quetiapine are approved for treatment of bipolar depression.
Bipolar affective
(manic-depressive) disorder occurs in 1–3% of the adult population. It may
begin in childhood, but most cases are first diagnosed in the third and fourth
decades of life. The key symptoms of bipolar disorder in the manic phase are
excitement, hyperactivity, impulsivity, disinhibition, aggression, diminished
need for sleep, psychotic symptoms in some (but not all) patients, and
cognitive impairment. Depression in bipolar patients is phe-nomenologically
similar to that of major depression, with the key features being depressed
mood, diurnal variation, sleep disturbance, anxiety, and sometimes, psychotic
symptoms. Mixed manic and depressive symptoms are also seen. Patients with
bipolar disorder are at high risk for suicide.
The sequence, number,
and intensity of manic and depres-sive episodes are highly variable. The cause
of the mood swingscharacteristic of bipolar affective disorder is unknown,
although a preponderance of catecholamine-related activity may be present.
Drugs that increase this activity tend to exacerbate mania, whereas those that
reduce activity of dopamine or norepinephrine relieve mania. Acetylcholine or
glutamate may also be involved. The nature of the abrupt switch from mania to
depression experienced by some patients is uncertain. Bipolar disorder has a
strong famil-ial component, and there is abundant evidence that bipolar
disor-der is genetically determined.
Many of the genes that
increase vulnerability to bipolar disor-der are common to schizophrenia but
some genes appear to be unique to each disorder. Genome-wide association
studies of psy-chotic bipolar disorder have shown replicated linkage to
chromo-somes 8p and 13q. Several candidate genes have shown association with
bipolar disorder with psychotic features and with schizophre-nia. These include
genes for dysbindin, DAOA/G30,
disrupted-inschizophrenia-1 ( DISC-1),
and neuregulin 1.
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2023 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.