With strategies such as Transcranial Magnetic Stimulation (TMS), Ketamine, and psychedelics becoming more prevalent for treatment-resistant depression, it is helpful to take a look at what this entity really means. Not everyone who is being referred for either TMS or treatment with Ketamine may have "true" treatment-resistant depression, and then there is what is called "pseudo-resistance."
In simple terms,
treatment-resistant depression implies that depression has not reached
sufficient remission after adequate treatment. Remission is defined as
clinical improvement with few signs of depression still remaining and a lower
likelihood of subsequent exacerbations. About 15% of people with
depression may eventually develop treatment-resistant depression (Berlim &
Turecki, 2007). Treatment-resistant depression has been variously defined, but
the most commonly accepted definition is as follows (Souery et al., 2007):
A person with depression
is considered to have treatment-resistant depression when consecutive
treatments with two antidepressants from two different
pharmacologic classes, used for a sufficient length of time at
an adequate dose, fail to produce significant improvement. This is
further elaborated below:
- Two different pharmacologic classes mean antidepressants have different mechanisms of action. For example,
Selective Serotonin Reuptake Inhibitors (SSRIs) versus Serotonin
Norepinephrine Reuptake Inhibitors (SNRIs).
- An adequate length of time is an antidepressant trial
lasting at least 4 weeks.
- An adequate dose is the minimum effective daily dose
recommended in the drug package insert.
- Significant improvement is a score of less than 17 on
the 17-item Hamilton Depression Rating Scale.
This definition of treatment-resistant depression has several problems. First, it assumes that switching from one class of antidepressants to another may be a more effective strategy than switching within the class. Second, it doesn’t discuss the role of psychotherapy. Third, it is silent on functional improvement and improvement in quality of life and relies only on clinical improvement to define treatment resistance. Nevertheless, this is the most accepted definition
of treatment-resistant depression.
What is
Pseudo-Resistance?
Before you jump the gun
and diagnose yourself with treatment-resistant depression, first rule out if
this is pseudo-resistance. About 60% of people initially classified as having
treatment-resistant depression may actually have pseudo-resistance (Berlim
& Turecki, 2007). The causes of pseudo-resistance are below (Berlim &
Turecki, 2007; Souery et al., 2006):
- Inadequate dosing of the antidepressants: This may be
due to staying at a low dose of the antidepressants because of initial
side effects that have subsequently abated. Other causes could be drug
interactions that make the antidepressant less effective or an individual's rapid metabolism of the antidepressant.
- Inadequate duration of the antidepressants: Switching
medications too soon and concluding that a given medication is ineffective
also contributes to pseudo-resistance.
- Inadequate adherence: Not taking the antidepressants as
prescribed due to side effects or forgetting to take them accounts for
about 20% of scenarios that are considered treatment-resistant depression.
- Improper diagnosis: This includes:
- Failure to diagnose an underlying bipolar disorder.
- Failure to diagnose psychotic symptoms associated with
depression.
- Failure to diagnose melancholic depression. Melancholic
depression is a more severe kind of depression characterized by loss of
pleasure in all, almost all activities, no emotional response when
something good happens, a profound sense of despondency or despair,
depression that is worse in the morning, early-morning awakening,
appearing markedly slowed down or agitated, poor appetite or weight loss,
and excessive or inappropriate guilt (American Psychiatric Association,
2013).
- Failure to diagnose co-occurring anxiety or personality
disorders.
- Failure to identify underlying medical conditions that
may be associated with depression, such as hypothyroidism.
If you haven’t responded
to a couple of trials of antidepressants, it may be worthwhile to explore the
above possibilities in collaboration with your antidepressant prescriber.
What are the Risk
Factors for Treatment-Resistant Depression?
While there is no
definitive cause as to why some people with depression will develop
treatment-resistant depression, research does demonstrate certain risk factors
that predispose one to develop treatment-resistant depression. These include
the following (Souery et al., 2007):
- Co-occurring anxiety disorders, particularly panic
disorder and social phobia.
- Having suicidal thoughts during the current episode of
depression.
- Greater severity of depressive symptoms.
- Presence of melancholic symptoms of depression
(described before).
- History of recurrent episodes of depression.
- More than one psychiatric hospitalization in the past.
- Age of onset of depression before 18 years.
- Non-response to the first antidepressant in one’s
lifetime.
- Co-occurring personality disorder.
Being aware of these
risk factors helps an individual plan ahead for treatment as
treatment-resistant depression may require a combination of medications or
other non-pharmacological strategies.
To learn more about evidence-based
self-management techniques that are proven to work for depression, check out
Dr. Duggal's Author
Page.
HARPREET S. DUGGAL, MD,
FAPA
REFERENCES:
American Psychiatric
Association (2013). Diagnostic and statistical manual of mental
disorders (5th ed.). Arlington, VA: American Psychiatric Association.
Berlim, M. T., &
Turecki, G. (2007). Definition, assessment, and staging of treatment-resistant
refractory major depression: a review of current concepts and methods. Canadian
Journal of Psychiatry, 52, 46-54.
Souery, D., Oswald, P., Massat, I.,
Bailer, U., Bollen, J., Demyttenaere, K., Kasper, S., Lecrubier, Y.,
Montgomery, S., Serretti, A., Zohar, J., & Mendlewicz, J. for the Group for
the Study of Resistant Depression (GSRD) (2007). Clinical factors associated
with treatment resistance in major depressive disorder: results from a European
multicenter study. Journal of Clinical
Psychiatry, 68(7), 1062-1070.
Souery, D., Papakostas,
G. I., & Trivedi, M. H. (2006). Treatment-resistant depression. Journal
of Clinical Psychiatry, 67(suppl 6), 16-22.
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