Category: Mental Illness

Rats’ visual systems made plastic by anti-depressants

Blogging on Peer-Reviewed ResearchMy mind raced for potential titles to a post when I read the recent report from Science, ‘The Antidepressant Fluoxetine Restores Plasticity in the Adult Visual Cortex,’ by a team headed by José Fernando Maya Vetencourt (abstract), but I’ve opted to be demure, rather than go with some of my other options (like ‘Anti-depressants the “Cocoon” pool for brain?’ or something similarly outrageous).

The research team investigated wither fluoxetine, a selective serotonin reuptake inhibitor (SSRI), could restore plasticity in the visual system of adult rats. They chose fluoxetine because long-term regimens of the drug promote neurogenesis and synaptogenesis in the hippocampus and increased activity of neurotrophin brain-derived neurotrophic factor (BDNF) and its primary receptor, TrkB (close paraphrase to the original article). These effects have been shown essential to the drug’s effect; block one of these processes, and the anti-depressant doesn’t work nearly as well. In order to test plasticity, the team studied how rats responded to monocular deprivation — covering one eye — both the initial shift in ocular dominance and then the recovery of visual function after long-term monocular deprivation. In general, the fluoxetine-treated rats responded in exaggerated fashion to both conditions, suggesting that plasticity was greater with long-term administration of the drug. From the abstract:

We found that chronic administration of fluoxetine reinstates ocular dominance plasticity in adulthood and promotes the recovery of visual functions in adult amblyopic animals, as tested electrophysiologically and behaviorally. These effects were accompanied by reduced intracortical inhibition and increased expression of brain-derived neurotrophic factor in the visual cortex. Cortical administration of diazepam prevented the effects induced by fluoxetine, indicating that the reduction of intracortical inhibition promotes visual cortical plasticity in the adult. Our results suggest a potential clinical application for fluoxetine in amblyopia as well as new mechanisms for the therapeutic effects of antidepressants and for the pathophysiology of mood disorders.

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Antidepressants suppress identity?

Another interesting one from The New York Times, Who Are We? Coming of Age on Antidepressants, by Dr. Richard A. Friedman; I found this one really well done, asking more questions than it answers, but thought-provoking.

The introduction to the article lays out the central existential question posed by long-term treatment with anti-depressants, especially for patients who started on their regimens when very young:

“I’ve grown up on medication,” my patient Julie told me recently. “I don’t have a sense of who I really am without it.”
At 31, she had been on one antidepressant or another nearly continuously since she was 14. There was little question that she had very serious depression and had survived several suicide attempts. In fact, she credited the medication with saving her life.
But now she was raising an equally fundamental question: how the drugs might have affected her psychological development and core identity.

As Friedman points out, the medical testing for these pharmaceuticals doesn’t include long-term research anywhere close to the lengths of time that people are actually spending on the drugs: the longest maintenance study — done on Effexor — lasted two years.

But the more subtle issues that Friedman raises, as far as I’m concerned, are the questions of identity that are clouded by long-term anti-depressant use. He discusses one woman who was concerned about her ‘low sex drive’ and pressure from her boyfriend to have sex after eight years on libido-reducing Zoloft: ‘She had understandably mistaken the side effect of the drug for her “normal” sexual desire and was shocked when I explained it: “And I thought it was just me!”’ I can’t tell from the way Friedman writes this how he feels about the idea that an individual has a ‘normal’ sex drive, something that might exist ‘prior to’ or ‘independent of’ any outside influences, whether that influence be an anti-depressant or a particular life event or the effects of interpersonal dynamics with a partner.

The idea that the ‘anti-depressed’ state might become ‘normal,’ both in the medical sense that intervention seeks to create this state and in the sense that a patient spends so much time in the drug-influenced state that it becomes a kind of reference, suggests yet another way that cultural expectations might become biological ‘nature.’

Differences in dyslexia

A fascinating article came out in the Science section of The New York Times: Patterns: Dyslexia as Different as Day and Night, by Eric Nagourney. The article is based on an original research piece by Wai Ting Siok, Zhendong Niu, Zhen Jin, Charles A. Perfetti, and Li Hai Tan, who examined the abnormalities in brain activity associated with dyslexia in Chinese speakers (in comparison to better documented examples of the disorder in English speakers).

The basic result is simple, but intriguing, especially in light of some of the other research we’ve discussed on how brain areas linked to language differ, Two languages, one brain and theory of mind:

The report, which appeared last week in The Proceedings of the National Academy of Sciences, found that changes in the brain that may contribute to dyslexia are different for English speakers and Chinese speakers.
The difference may be explained by the fact that English is an alphabetic language, the researchers said. A reader sees a letter and associates it with a sound. Chinese characters, on the other hand, correspond to syllables and require much more memorization.

In English-speaking individuals, dyslexia shows up in neuroimaging studies as weak activity in left occipitotemporal and temporoparietal regions of the brain. The researchers find out, however, that readers of Chinese with dyslexia have a different anomaly in their brain, perhaps due to the difference between alphabetic and ideographic languages. Children with (from the abstract) ‘impaired reading in logographic Chinese exhibited reduced gray matter volume in a left middle frontal gyrus region,’ an area that had already been found to be active in reading and writing Chinese characters. ‘By contrast, Chinese dyslexics did not show functional or structural (i.e., volumetric gray matter) differences from normal subjects in the more posterior brain systems that have been shown to be abnormal in alphabetic-language dyslexics’: the abstract details.

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Ethnography and the Everyday: Knapp’s Appetites

In my medical anthropology class we are now reading Caroline Knapp’s Appetites, a memoir of her struggles with anorexia and a meditation on culture, gender, and being a woman. This book is flip side to Kolata’s Rethinking Thin, linking eating and weight to cultural meanings, social relationships, the media, and more. In the end, I hope that my students will realize that both biology and culture matter, and that one of the best ways to link those two is through a focus on experience and behavior. In turn, experience and behavior can be grasped as being the manifestation, concretization and direction of brain and body in context.

On Thursdays the students take charge of half the class, and yesterday was a great discussion. The group in charge began with Knapp’s discussion of the front cover of a Shape magazine featuring Elle Macpherson, perfectly recovered after giving birth just some months before. Then they put all of us to work on creating the covers for other magazines—Seventeen, Cosmopolitan, Women’s Health, and Men’s Health. We’re on deadline and have to sell, sell, sell

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A Round Up

Addiction

Benedict Carey, When People Drink Themselves Silly, and Why
Addresses the links between heavy drinking and social context, quite a nice piece summarizing some key anthropological and social psychological research  

Jeneen Interlandi, What Addicts Need
The polar opposite of the Carey piece, arguing for a psychobiological approach to understanding addiction.

First Peek into Deepest Recesses of Human Brain
Advances in neuroimaging of the ventral tegmental area. 

Drinking Makes Heart Grow More Sorrowful, Study Finds
Drinking helps lock memories in place, at least in this rat research 

Radley Balko, Better Dead Than High
Death as a social deterrent, based on restricting access of naloxene for overdoses 

Jennifer Vineyard, ‘Harry Potter’ Is Addictive, Study Concludes
Withdrawal and craving after the series ends… 

Mental Health

Paige Parvin, Why Is This Man Smiling
The Dalai Lama and Emory scientists team up to examine happiness 

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Autism and Understanding Others

Amanda Baggs presents her own life and thoughts in her YouTube video, In My Language, her translation of how she is in a constant conversation with the world around her.  She is autistic and does not speak.  But she can type, and after three minutes showing her interacting with her environment, she uses computer technology to explain herself to us.


I came across this video through Tara Parker-Pope’s post, The Language of Autism.  As Parker-Pope relates, “Ms. Baggs does far more than give us a vivid glimpse into her mind. Her video is a clarion call on behalf of people with cognitive disabilities whose way of communicating isn’t understood by the rest of the world.”

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