Burden of bipolar depression: impact of disorder and medications on quality of life

Article (PDF Available)inCNS Drugs 22(5):389-406 · February 2008with119 Reads
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Abstract
Bipolar disorder is a complex, chronic psychiatric condition characterized by recurring episodes of depressive illness and mania or hypomania. Although the manic or hypomanic episodes define the disorder, recent research has shown that depressive symptoms predominate over manic symptoms in the majority of patients, and that bipolar depression accounts for much of the significant morbidity and mortality associated with bipolar disorder. Given these findings, there has been a recent upsurge of interest in furthering our understanding of the burden of depression in bipolar disorder. At the same time, increasing scientific attention is now being paid to expanding the measurement of outcome in bipolar disorder to encompass broader indicators of response, one of which is the assessment of quality of life (QOL). In this review, we provide a summary of the current knowledge about QOL in the depressive phase of bipolar disorder, and the effects of pharmacological treatment interventions for bipolar disorder upon QOL. It appears that QOL is poorer in bipolar disorder than in other mood disorders and anxiety disorders, but that schizophrenia might compromise QOL more severely than bipolar disorder. Existing data also suggest that, for patients with bipolar disorder, QOL is negatively associated with depression, both as a cross-sectional mood state and perhaps also as a feature of the patient's course. Despite its clinical and public health importance, bipolar depression has only recently started to receive the attention it warrants in clinical trials, and many important questions about its optimal pharmacological management remain to be answered. There is also a paucity of information about the impact of pharmacological interventions on QOL in bipolar depression. To our knowledge, only two clinical trials to date have specifically examined the impact of medications on QOL in patients with bipolar depression. A small number of other studies have examined the effects of depressive symptoms on QOL in patients who are experiencing manic or mixed episodes. Nonetheless, QOL appears to be a meaningful and important indicator of outcome and recovery in this patient population, and one that warrants further scientific interest and energy.
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2008, Vol. 22, No. 5 (pp. 389-406)
ISSN: 1172-7047
Review Article
Burden of Bipolar Depression
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CNS Drugs 2008; 22 (5): 389-406
R
EVIEW
A
RTICLE
1172-7047/08/0005-0389/$48.00/0
2008 Adis Data Information BV. All rights reserved.
Burden of Bipolar Depression
Impact of Disorder and Medications on Quality of Life
Erin E. Michalak,
1
Greg Murray,
2
Allan H. Young
1
and Raymond W. Lam
1
1 Department of Psychiatry, University of British Columbia, Vancouver, British
Columbia, Canada
2 Faculty of Life and Social Sciences, Swinburne University of Technology, Melbourne,
Victoria, Australia
Contents
Abstract .................................................................................... 389
1. Bipolar Disorder .......................................................................... 390
2. Bipolar Depression ....................................................................... 391
3. Assessing Outcome in Bipolar Disorder ..................................................... 392
4. Quality of Life (QOL) Research ............................................................ 392
4.1 QOL Research in Bipolar Disorder ...................................................... 393
4.1.1 Effects of Bipolar Disorder versus Other Psychiatric Conditions on QOL ............... 394
4.2 Effects of Bipolar Depression on QOL .................................................. 396
4.2.1 Effects of Medications on QOL in Bipolar Depression ............................... 397
5. Discussion ............................................................................... 400
6. Future Research Directions ................................................................ 401
7. Conclusions ............................................................................. 403
Bipolar disorder is a complex, chronic psychiatric condition characterized by
Abstract
recurring episodes of depressive illness and mania or hypomania. Although the
manic or hypomanic episodes define the disorder, recent research has shown that
depressive symptoms predominate over manic symptoms in the majority of
patients, and that bipolar depression accounts for much of the significant morbidi-
ty and mortality associated with bipolar disorder. Given these findings, there has
been a recent upsurge of interest in furthering our understanding of the burden of
depression in bipolar disorder. At the same time, increasing scientific attention is
now being paid to expanding the measurement of outcome in bipolar disorder to
encompass broader indicators of response, one of which is the assessment of
quality of life (QOL).
In this review, we provide a summary of the current knowledge about QOL in
the depressive phase of bipolar disorder, and the effects of pharmacological
treatment interventions for bipolar disorder upon QOL. It appears that QOL is
poorer in bipolar disorder than in other mood disorders and anxiety disorders, but
that schizophrenia might compromise QOL more severely than bipolar disorder.
Existing data also suggest that, for patients with bipolar disorder, QOL is
negatively associated with depression, both as a cross-sectional mood state and
perhaps also as a feature of the patient’s course. Despite its clinical and public
health importance, bipolar depression has only recently started to receive the
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
390 Michalak et al.
attention it warrants in clinical trials, and many important questions about its
optimal pharmacological management remain to be answered. There is also a
paucity of information about the impact of pharmacological interventions on QOL
in bipolar depression. To our knowledge, only two clinical trials to date have
specifically examined the impact of medications on QOL in patients with bipolar
depression. A small number of other studies have examined the effects of
depressive symptoms on QOL in patients who are experiencing manic or mixed
episodes. Nonetheless, QOL appears to be a meaningful and important indicator
of outcome and recovery in this patient population, and one that warrants further
scientific interest and energy.
1. Bipolar Disorder work (SFBN)
[3]
cohort of patients using the National
Institute of Mental Health Life Chart Method
(NIMH-LCM),
[4]
where patients were observed to
Bipolar disorder is a chronic psychiatric condi-
experience approximately three times more depres-
tion characterized by recurring episodes of depres-
sive symptoms than hypomanic or manic symptoms
sive illness and at least one episode of mania or
over a 12-month period.
[5,6]
hypomania. The condition is both complex and het-
erogeneous. A patient with bipolar disorder can Given these findings, it is not surprising that
experience symptoms of depression, hypomania, bipolar disorder is associated with significant mor-
mania or psychosis, and indeed can experience com- bidity. In the year 2000, the WHO estimated that the
binations of these emotional states, or cycle rapidly condition was the sixth leading cause of disability
between them. Marked variability occurs between worldwide among young adults (i.e. 15–44 years of
patients in terms of the type, number and length of age).
[7]
A woman who develops bipolar disorder at
episodes experienced over a lifetime, the severity the age of 25 years may lose 9 years in life expectan-
and type of symptoms encountered, and the degree cy (due to cardiovascular and other medical prob-
of inter-episode recovery achieved. This being said, lems), 14 years of productivity and 12 years of
it is now appreciated that depression is the predomi- normal health.
[8]
While the condition has considera-
nant mood symptom in bipolar disorder, with the ble ramifications at an individual level, it also has a
majority of patients experiencing either symptoms significant impact at a societal level. Bipolar disor-
or full episodes of depression much more frequently der type I is estimated to affect at least 1% of
than those of mania or hypomania.
[1,2]
individuals worldwide,
[9]
making it a serious public
health concern. The broader category of bipolar
Judd and colleagues’
[2]
seminal prospective stud-
spectrum disorders (encompassing, for example, bi-
ies of the natural course of bipolar disorder (for
polar disorder type II, bipolar disorder not otherwise
average timeframes of over a decade) have demon-
specified [NOS] and cyclothymia
[10]
) has been less
strated that patients with bipolar disorder type I
extensively studied, but is estimated to be more
(characterized by episodes of depression and at least
prevalent, affecting up to 8% of the population.
[11]
one episode of mania) experience symptoms of de-
pression for 30.6% of weeks, compared with 9.8% In one widely cited study, the direct and indirect
of weeks for hypomanic or manic symptoms. Pa- costs associated with bipolar disorder were estimat-
tients with bipolar disorder type II (characterized by ed to be $US45 billion in the US during 1991, of
episodes of depression and at least one episode of which only $US7 billion was due to actual treatment
hypomania) experienced depression for a staggering costs.
[12]
However, lost productivity within salaried
51.9% of weeks, compared with 1.4% of weeks for employees and homemakers accounted for costs of
hypomanic symptoms. Similar findings have been approximately $US20 billion. The individual and
reported for the Stanley Foundation Bipolar Net- economic burden associated with bipolar disorder is
2008 Adis Data Information BV. All rights reserved. CNS Drugs 2008; 22 (5)
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Burden of Bipolar Depression 391
likely exacerbated by the fact that the condition is (including disorder) to produce individual differ-
often underdiagnosed or misdiagnosed, resulting in
ences in QOL.
[22]
either undertreatment or mistreatment,
[13]
potential-
As previously described, recent longitudinal
ly heightened healthcare costs,
[14,15]
and often ex-
studies have indicated a preponderance of depres-
tended periods of disability for the individual con-
sive symptoms over hypomanic or manic symptoms
cerned.
[16]
in patients with both bipolar disorder types I and
II.
[1,2,23]
However, bipolar depression has been
somewhat neglected in past psychiatry research, and
2. Bipolar Depression
has only recently begun to attract the scientific at-
tention it warrants. Much of the morbidity and mor-
It is useful to commence by stating three prem-
tality in bipolar disorder appears to be a conse-
ises of our critical summary of the existing litera-
quence of the depressive phase of the disorder,
ture. Firstly, the review is not limited to categorical-
rather than the hypomanic or manic phases. For
ly defined episodes of bipolar depression, but will
example, patients experiencing acute depressive or
also include reference to subsyndromal depressive
mixed episodes are at significantly higher risk of
symptoms. There is growing nosological consensus
suicide, panic disorder and psychosis compared with
that the nature of depression (at least in the unipolar
patients experiencing purely manic episodes.
[24]
Fur-
case) is fundamentally dimensional rather than cate-
thermore, early intervention strategies are less relia-
gorical,
[17]
and recent longitudinal research in bi-
ble for bipolar depression than mania because of the
polar disorder highlights the clinical importance of
more insidious pattern typically seen in the depres-
continuously waxing and waning depressive symp-
sive prodrome.
[25]
toms.
[1,2]
The term bipolar depression is therefore
used here to define our focus on the depressive
Recovery from depressive episodes often takes
symptoms and diagnosable depressive episodes that
longer than recovery from manic episodes, with a
occur in the course of bipolar disorder. Secondly, we
median time of 9 weeks as opposed to 5 weeks.
[26]
do not imply by this term that bipolar depression can
Several studies have also indicated that subsyn-
be readily distinguished from unipolar depression
dromal symptoms of depression, now recognized as
(for arguments against this distinction, see, for ex-
being markedly prevalent in inter-episode patients
ample, Cuellar et al.,
[18]
Schweitzer et al.
[19]
and
with bipolar disorder,
[1,2,27,28]
can be predictive of
Murray et al.
[20]
).
significant functional impairment in this population.
For example, a study of 759 patients recruited to the
In this review, we will present data suggesting
SFBN reported that subthreshold depressive symp-
differences between bipolar and unipolar depression
toms were significantly predictive of impaired role
in terms of QOL outcomes, but given that bipolar
functioning (specifically, impairment in work and
depression occurs in the context of a more complex
home functioning roles, as well as impairment in
disorder, it cannot be assumed that these differences
relationships with family and friends) in patients
are due to intrinsic differences in the two presenta-
with predominantly (75%) bipolar disorder type I.
[6]
tions of depression. Finally, while the literature re-
Odds of experiencing significant impairment in role
viewed here is limited almost entirely to simple
functioning among patients with subthreshold de-
bivariate investigation of disorder parameters as de-
pressive symptoms were 3- to 6-fold greater than for
terminants of QOL, we have argued elsewhere
[21]
those who were not depressed. Furthermore, data
that as research into QOL in bipolar disorder ma-
from Altshuler et al.
[28]
indicated that there was a
tures, a multivariate approach will become more
significant association between severity of sub-
prominent. More complete models of QOL in bi-
threshold symptoms and degree of role impairment,
polar disorder should include measures of the range
consistent with results from the study by Yatham
of variables (including stable temperamental vulner-
and colleagues
[29]
of Short Form-36 (SF-36)