Yet another write-up on Nature suggesting that an overactive limbic system may causally contribute to a dampened prefrontal cortex, presumably leading to anxiety, depression, and even cases of ADD in some folks. Unfortunately this is a pay-to-read article, and I’m not a subscriber, but the abstract and this available box of information ought to do the trick. Here are the most relevant excerpts:
“Even quite mild acute uncontrollable stress can cause a rapid and dramatic loss of prefrontal cognitive abilities, and more prolonged stress exposure causes architectural changes in prefrontal dendrites.”
“Under conditions of psychological stress the amygdala activates stress pathways in the hypothalamus and brainstem, which evokes high levels of noradrenaline (NA) and dopamine (DA) release. This impairs PFC regulation but strengthens amygdala function, thus setting up a ‘vicious cycle’. For example, high levels of catecholamines, such as occur during stress, strengthen fear conditioning mediated by the amygdala. By contrast, stress impairs higher-order PFC abilities such as working memory and attention regulation. Thus, attention regulation switches from thoughtful ‘top-down’ control by the PFC that is based on what is most relevant to the task at hand to ‘bottom-up’ control by the sensory cortices, whereby the salience of the stimulus (for example, whether it is brightly coloured, loud or moving) captures our attention. [emphasis mine]”
What’s particularly interesting for me is comparing my own neural SPECT scans from the Amen Clinic to these statements. I know. I know. Most psychiatrists are critical of Dr. Amen’s methods, which is fine. I’m neither making a plug for him nor am I criticizing him. The reader can decide his/her own opinion on the matter. One of the complaints, however, is that SPECT scans aren’t very good at actually tracing neurotransmitters, which have been implicated in most mental illnesses, since they primarily focus on blood flow, thereby making their relevance to psychiatric diagnosis quite limited. Sure, you can get a good overview of one’s brain function, detecting tumors, Alzheimer’s, epilepsy, etc., but there seems to be no analysis of the chemicals themselves or the receptors that metabolize them, which means those with such issues won’t find any real benefit.
Despite all of this, however, we can be certain of the simple fact that my own scans showed, among other things, increased blood flow to my limbic area and slightly decreased blood flow to my dorso-lateral prefrontal cortex, which seems to me highly suggestive of the aforementioned scenario and perfectly in sync with my own subjective perception of symptoms, e.g. depression, inattention, anxiety, obsessions and compulsions, etc. Likewise, it fits fairly well with my own history since my younger years, in retrospect, seemed to have roughly followed the progression of nervous tics, full-blown anxiety/depression, obsessive-compulsive disorder, then ADD. I purposely write ADD, by the way, and not ADHD since I was never hyperactive, and it just makes more sense to use the old terminology for my experience rather than ADHD-PI. At any rate, I’m only aware of the nervous tics beginning first because I’ve been told by my parents of the incessant cough that the pediatrician chalked-up to anxiety as opposed to some sort of illness. Unfortunately, I was always so quiet, introverted, and well-behaved that I probably never gave anyone a reason to think something was wrong, and it’s only now that the pieces can be put together more accurately.
In fourth grade I very clearly recall one of the earliest manifestations of textbook OCD during an incident in which I felt compelled to hold the left side metal support of my desk with my right hand so that my fingers touched, prompting the girl next to me to ask what I was doing. (I wonder if she remembers too) During those years I also began to stop swallowing my saliva from time to time for fear of being poisoned, which I hid well by either spitting when outside or wiping it on my sleeve when inside, always hiding it as best as I could because hey, I may have been a mentally ill kid, but even I knew that stuff was crazy. It was around that time, also, that teachers began telling my parents that I would daydream a lot, spacing out during lessons and such, though no one really knew what the story was, assuming I was just lazy and unmotivated — a perfectly reasonable conclusion based on the external data. From there it only got worse, prompting me to eventually seek treatment, which helped immensely in various ways and to varying degrees, but never permanently as one would like. I’ve had numerous relapses over the years, one in particular being the result of my foolish decision to totally ween myself off of a medication without the doctor’s knowledge. Helpful hint: don’t do it.
From what I’ve gathered, however, it all seems perfectly reasonable to suspect that a fiery limbic system somehow caused these issues and still continues to do so to this day. The good news, however, is that a variety of cognitive and behavioral techniques have shown serious promise is reversing many of these tendencies, as I pointed out in my last entry, so I may not be as doomed as I once thought.