ClinicSpeak: Bipolar disorder and MS

Bipolar disorder may be commoner in MSers. #MSBlog #MSResearch #ClinicSpeak

"What is biploar disorder? Bipolar disorder, also known as bipolar affective disorder, manic-depressive disorder, or manic depression, is a mental illness classified by psychiatry as a mood disorder. Individuals with bipolar disorder experience episodes of an elevated or agitated mood known as mania (or hypomania, depending on the severity) alternating with episodes of depression."

"The study below is interesting and suggest MSers are at higher risk of having bipolar disorders compared to the normal population. Is this an association of two separate diseases or does MS cause or trigger a bipolar disorder in some MSers? To answer this question we would need to a population based study looking to see the timing of the two diagnoses relative to each other and to assess whether or not there is familial clustering of these disorders. If MS and bipolar disorders were simply associated with each other you should find them to be independently clustered in families of MSers. If on the other hand MS caused bipolar disorders then the diagnosis of MS should precede the diagnosis of MS in the majority of MSers and it should not be more common in siblings who are unaffected by MS. The age of the unaffected and affected siblings will need to be taken into account when doing this analysis as age is a risk factor for both diseases. The older you are, i.e. past 50, the less likely you are to develop MS and/or bipolar disorders. These types of epidemiological studies are best done in Scandinavia where population databases exist and can be linked. I may ask Nils Koch-Henriksen, a Danish colleague responsible for the national MS register, to try and confirm these results."

"Confirming these results are important and will alert us to fact that we should be looking out for the diagnosis in our own populations of MSers. I have been working in the field of MS for 20 years and in that time have only seen two MSers with coexistent bipolar disorder; this makes the occurrence rare unless I am missing the diagnosis."

Epub: Carta et al. The risk of Bipolar Disorders in Multiple Sclerosis. J Affect Disord. 2013 Nov 19. 

BACKGROUND: The aim was to determine the risk of Mood Disorders (MD), particularly Bipolar Disorders (BD), in MS using standardized psychiatric diagnostic tools.

METHODS: Case-control study. Cases: 201 consecutive-MSers. Controls: 804 sex- and age-matched subjects without MS, randomly selected from a database concurrently used for an epidemiological study on the MD prevalence in the community. Psychiatric diagnoses according to DSM-IV were determined by physicians using structured interview tools (ANTAS-SCID).

RESULTS: Compared to controls, MS patients had a higher lifetime prevalence of DSM-IV Major Depressive Disorders (MDD; P<0.0001), BD I (P=0.05), BD II (P<0.0001) and Cyclothymia (P=0.0001). As people with MS had a higher risk of depressive and bipolar spectrum disorders, ratio MDD/bipolar spectrum disorders was lower among cases (P<0.005) indicating a higher association with Bipolar Spectrum Disorders and MS.

LIMITATIONS: MS diagnosis was differently collected in cases and controls. Even if this might have produced false negatives in controls, it would have reinforced the null hypothesis of no increased risk for MD in MS; therefore, it does not invalidate the results of the study.

CONCLUSIONS: This study was the first to show an association between BD and MS using standardized diagnostic tools and a case-control design. The results suggest a risk of under-diagnosis of BD (particularly type II) in MS and caution in prescribing antidepressants to people with depressive episodes in MS without prior excluding BD. The association between auto-immune degenerative diseases (like MS) and BD may be an interesting field for the study of the pathogenic hypothesis.

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