Posted by Phillipa on March 25, 2011, at 21:41:39
Seems the brain may be able to not stop growing at 20 as believed but continue later in life. Phillipa
From Medscape Medical News > Psychiatry
Cortical Thinning May Predict Response to Depression Therapy
Deborah BrauserAuthors and Disclosures
March 25, 2011 (San Antonio, Texas) Reduced cortical thickness not only may be a biomarker for late-life depression (LLD) but also may predict a lower treatment response to psychotherapy, new research suggests.
In a study of 24 patients with LLD presented here at the American Association for Geriatric Psychiatry (AAGP) 2011 Annual Meeting, those who did not respond to psychotherapy at the end of 12 weeks had thinner cortex in several specific brain regions, including the bilateral posterior cingulate and parahippocampal cortices, than did those who responded favorably.
In addition, all patients with LLD had significantly thinner cortex in the right frontal, parietal, and temporal brain regions than did their 12 healthy counterparts.
"Our findings suggest more distributed right hemisphere cortical abnormalities in LLD than have been previously reported. Frontal involvement is fairly common but that these effects were seen almost exclusively in the right was surprising and exciting," said lead investigator R. Scott Mackin, PhD, assistant professor of psychiatry at the University of California, San Francisco. during his presentation.
Dr. R. Scott Mackin"We also found that bilateral cortical thinning may be an important phenotype of individuals at higher risk for poor psychotherapy response," he added.
Dr. Mackin was recognized by the AAGP as the 2011 Barry Lebowitz Early Career Scientist for this study. This award is presented annually "for the best unpublished paper by an early career investigator," the organization reports in a release.
Cortical Thickness Unexplored
"Cortical atrophy has been associated with LLD, but patterns of cortical thickness in LLD have not yet been explored," the investigators write, noting that most studies have focused on cortical volume loss.
"Further, cortical atrophy has been posited as a contributor to poor antidepressant treatment response in LLD but the impact of cortical thickness on psychotherapy response is unknown," they add.
Dr. Mackin has been focusing his overall research program on evaluating neurobiological factors associated with LLD, as well as poor treatment outcomes in this older population.
"Delineating structural brain abnormalities is an important avenue to improving our understanding of the etiology of depressive symptoms and could lead to improved treatments," said Dr. Mackin during his presentation.
"Looking at psychotherapy outcomes is important because it involves multiple cognitive functions, such as problem solving, abstract reasoning, initiation, attention, memory and language," he added.
For this study, all participants (mean age, 72.6 years) underwent magnetic resonance imaging (MRI) of the brain.
Cortical thickness was defined as "distance from cortical grey matter/cerebral white matter and cortical grey matter/cerebrospinal fluid tissue boundaries."
The 24 patients with current LLD also underwent once-weekly sessions of psychotherapy. Treatment response was defined as a 50% reduction in depressive symptoms on the Hamilton Depression Rating Scale (HDRS). The baseline HDRS score for the patients with LLD was 22.4.
The healthy controls group had no current or significant history of depression.
Structural Markers
Results showed that 50% of the patients with LLD were psychotherapy responders at the 12-week endpoint and had a mean HDRS score of 7.3 vs 17.2 for the nonresponders (P < .01).
Compared with the responders, those who did not respond significantly to treatment had reduced cortical thickness in the bilateral posterior cingulate and parahippocampal cortices, as well as in the left paracentral, precuneus, cuneus, and insular cortices; and the right medial orbitofrontal cortex (OFC) and lateral occipital cortex.
"The significant bilateral posterior cingulate involvement is interesting because it's different from the anterior cingulate findings that have been reported in past medication studies," said Dr. Mackin.
"So we need to ask: is this a marker of resistance to treatment with psychotherapy that differs from medication response? Perhaps; we know that the posterior cingulate has more of an impact on learning and memory than the anterior cingulate does," he explained.
Limitations cited for the study included its small sample size and short follow-up period, that only 1 type of psychotherapy was used, that clinical characteristics such as social support were not evaluated, and that the etiology of the structural alterations is not clear.
"There is also significant potential for these older adults to have an underlying neurodegenerative disease such as cardiovascular disease and/or Alzheimer's disease," said Dr. Mackin.
He reported that the investigators hope to replicate the findings in a larger study that is currently underway, and to evaluate the relationship of cortical thickness to cognitive functioning, conduct multimodal analyses (such as through diffusion tensor imaging and cerebral blood flow), and to compare psychotherapy response to antidepressant response.
"The ultimate goal of this type of research is to try and identify the structural markers that could guide treatment matching for these older patients. We aren't there yet but that's what we're working towards. And I'm cautiously optimistic that we'll reach that goal."
During the Q&A session after the presentation, the award's namesake, Barry Lebowitz, PhD, professor of psychiatry and deputy director of the Sam and Rose Stein Institute for Research on Aging at the University of California, San Diego, said this was "a great paper representing a really ambitious program of research."
However, he questioned why the MRIs were done only on the participants before treatment and asked whether there were any post-treatment imaging data "that would allow you to test neurogenesis hypothesis of whether treatment actually fixes the broken brain."
Dr. Mackin responded that his investigative team is in the process of conducting a new study that will indeed include post-treatment data "that will build and extend these findings in several different ways."
Drugs Not the Whole Answer
"There's been a belief that psychotherapy is too long, too expensive, or isn't effective. But I think studies like this are going to help us rebalance our treatment strategies with elders, that drugs are fine but they are not the whole answer," session moderator Paul A. Newhouse, MD, director of the Clinical Neuroscience Research Unit and Brain Imaging Program at the University of Vermont College of Medicine in Burlington, told Medscape Medical News.
Dr. Paul A. NewhouseDr. Newhouse, who was not involved with this study, is the chair of the AAGP Research Committee. He said this study was given its award because "it's emblematic of a really new trend in geriatric psychiatry where we can actually begin to look directly at brain systems and mechanisms to investigate changes in behavior and treatment response."
"When I started my career, we didn't have the technology to do this. Now, we can directly probe brain activity and look at its relationship to symptoms and treatment outcome. I think that's an enormous advance."
He noted that he's "very excited" to see Dr. Mackin's follow-up data on the impact of psychotherapy.
"It will be interesting to see if he finds that psychotherapy actually changes brain structure. I think it might. There's pretty clear evidence that the brain is more plastic than we believed in the past, where we thought that the brain was fully formed by the time you hit 20 and all that could have happen after that was downhill. I think we're learning that that just isn't true," concluded Dr. Newhouse.
The study was funded by grants from the National Institute of Mental Health and from the National Center for Research Resources. Dr. Mackin and Dr. Newhouse have disclosed no relevant financial relationships.
American Association for Geriatric Psychiatry (AAGP) 2011 Annual Meeting: Presented during the Research Awards Paper Session on March 19, 2011.
poster:Phillipa
thread:981144
URL: http://www.dr-bob.org/babble/20110321/msgs/981144.html