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Research confirms "fuzzy thinking" in depression and bipolar disorder.

Mood disorders are points on a spectrum, not completely separate, according to a large, new study. People with depression or bipolar disorder often feel their thinking ability has gotten "fuzzy"--less sharp--than before their symptoms began. The new research shows that effect is real and that it is rooted in brain activity differences that show up on advanced brain scans.

The mounting evidence that these conditions both fall on a spectrum of mood disorders could transform the way doctors and patients think about, diagnose, and treat them.

The researchers tested 618 women--150 healthy women, 266 women with major depression that was either active or inactive at the time of testing, and 202 women with bipolar disorder who were not in a manic state when tested. The test required sustained concentration, and asked subjects to react rapidly when certain letters flashed briefly on a screen amid a random sequence of other letters.

Then 52 of the women--17 of the healthy women, 19 of the depressed women, and 16 of the bipolar women--took the same test again while inside the scanner at U-M's Functional Magnetic Resonance Imaging laboratory. (The researchers note that because of the expense of such scans and limits on finding participants, the fMRI group is still too small to make strong conclusions.)



As groups, women with depression or bipolar disorder did equally badly on the test. Compared with the group with no mental health conditions, the groups with either diagnosis lagged noticeably on this standard test of cognitive control.

While many individual women with depression or bipolar disorder scored as well on the test as healthy participants, nearly all the test-takers in the bottom 5 percent of performers had one of the two mood disorders.

On the detailed brain scans, the researchers found that the women with depression or bipolar disorder had different levels of activity than healthy women in the brain's right posterior parietal cortex. In those with depression, the activity in this area was higher than in healthy individuals, while in those with bipolar disorder it was lower. The area where the differences were seen helps control "executive function"--activities such as working memory, problem solving, and reasoning.

"In all, we show a shared cognitive dysfunction in women with mood disorders, which were pronounced in the cognitive control tests and more nuanced in scans," says Kelly Ryan, PhD, a U-M neuropsychologist and lead author of the study.

"Traditionally in psychiatry we look at a specific diagnosis, or category. But the neurobiology is not categorical--we're not finding huge differences between what clinicians see as categories of disease. This raises questions about traditional diagnoses," adds Ryan, who sees patients as a clinical assistant professor in the U-M Department of Psychiatry.

The number of patients involved is large for this kind of mental health study, according to the researchers, which makes the findings more meaningful. The researchers pooled data from several University of Michigan studies, including the Prechter Longitudinal Study of Bipolar Disorder. They focused on results only from women to take gender differences out of the mix.

The research appeared in the May 2015 issue of the journal BRAIN. DOI:

SOURCE: University of Michigan press release <>. Read the full article: <> (free online access)

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Title Annotation:Research Findings
Author:McCarthy, Kathleen
Publication:The Advocate (American Mental Health Counselors Association)
Date:Jun 1, 2015
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