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Deep brain stimulation, depression and ways of thinking

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I read in a recent New Scientist that some progress has been made in using deep brain stimulation (DBS) to find associations between electrical brain activity and ‘mood’ or mood changes. This appears to mean that there’s an electrical ‘signal’ for happiness, sadness, anxiety, frustration, and any other emotion we can give a name to. And to paraphrase Karl Marx, the point is not to understand the brain, but to change it – at least for those who suffer depression, PTSD, bipolar disorder, epilepsy and a host of other debilitating disorders. So that we can all be happy clapping productive people…

So what is DBS and where is it heading? Apparently, electrodes can be implanted in specific brain regions to monitor, and in some cases actually change, ‘negative’ electrical activity. I use scare quotes here not to indicate opposition, but to highlight the obvious, that one person’s negativity may not be another’s, and that eliminating the negative also means eliminating the positive, as one means nothing without the other. Similar to the point that loving everyone means loving no-one. 

But I’m getting ahead of myself with these ethical matters. Here’s a simple overview of DBS from the Mayo Clinic:

Deep brain stimulation involves implanting electrodes within certain areas of your brain. These electrodes produce electrical impulses that regulate abnormal impulses. Or, the electrical impulses can affect certain cells and chemicals within the brain.
The amount of stimulation in deep brain stimulation is controlled by a pacemaker-like device placed under the skin in your upper chest. A wire that travels under your skin connects this device to the electrodes in your brain.

The most recent research translated neural signals into the mood variations of seven epilepsy sufferers who were fitted with implanted electrodes. The participants filled out periodic questionnaires about their mood, and clear matches were supposedly found between those self-reports and patterns of brain signals. Based on this knowledge, a decoder was built that would recognise particular signal patterns related to particular moods. It was successful in detecting mood 75% of the time. Brain patterns varied between participants, but were confined mainly to the limbic system, a network essential to triggering swings of emotion. 

I’m not sure if I should be overly impressed with a sample size of seven and a 75% success rate, but I do think that this research is on the right track, and there will be increasingly successful pinpointing of brain activity in relation to mood in the future, as well as other improvements, for example in the use of electrodes. Currently there’s an issue around the damaging long-term effects of implants, and non-invasive systems are being developed that can stimulate the brain from outside the skull. And of course there’s that next step, modulating those mood swings to ‘fix’ them, or to head them off at the pass.

All of this raises vital questions in relation to causes and treatments. If we focus on that most difficult but pervasive condition, depression, which so many people I know are medicating themselves against, it would seem that a brain-stimulation ‘cure’ would be less damaging than any course of anti-depressants, but it completely bypasses the question of why so many people are apparently suffering from this condition these days. Johann Hari has written a bestseller on depression, Lost Connections, which I haven’t read though I’ve just obtained a copy, and I’ve heard his long-form interview on Sam Harris’ Waking Up podcast. So I’ll probably revisit this issue more than once.

The medical establishment is more interested in treatment than in causes, and generally investigates causes only so as to refine treatments, but severe depression has proved difficult to treat other than with drugs which may have severe side-effects when used long-term. Clinicians have used terms such as treatment-resistant depression (TRD) and major depressive disorder (MDD) to characterise these conditions, which are on the rise worldwide, particularly in the more affluent nations. 

DBS first came to prominence as a promising treatment for movement disorders such as Parkinson’s disease and dystonia (which causes muscles to contract uncontrollably). It has since been used for more psycho-neurological ailments such as OCD, Tourette syndrome and severe, treatment-resistant addiction, with modest but statistically significant benefits. It has even shown promise in the treatment of some forms of dementia. Side-effects have been mostly confined to surgical procedures.

Clearly this type of treatment will improve with better targeting and increased knowledge of brain regions and their interactions, and in the case of MDD, which can be overwhelmingly debilitating, it offers much hope of a better life. But the question remains – why is depression increasing, and why in those countries that appear to offer a richer and more stimulating environment for their citizens? 

Hari’s title, Lost Connections, more than hints at his view of this, and in a recent conversation it was suggested to me that, in more subsistence societies, most people are too busy struggling to survive and keep their families alive and well to have the time to be depressed. This might seem a slap in the face to MDD sufferers (and I might add that the person making that suggestion is on anti-depressants), but surely there’s a grain of truth to it. I’ve often had travellers say to me ‘you should visit x, the people there have so little, yet they’re so happy and relaxed’. Is this a matter of ignorance being bliss? I recall, as a fifteen-year-old in one of the world’s most affluent and educated countries, wagging school and reading one of my brother’s economics textbooks – he was at university – and trying to get my head around the laws of supply and demand. It occurred to me that this might take years – but what about the other subjects that gripped me when I read about them? Astronomy, physics, ancient history, music, subjects that often had little to do with each other but which you could spend your whole lifetime immersed in. Not to mention other childhood ambitions that hadn’t been let go, to be a great sport star, or rock star, or latter-day Casanova…

This sense, cultivated in advanced societies, that you can achieve anything you set your mind to, can easily overwhelm when you’re faced with so many choices, and so many gaps in skill and knowledge between what you are and what you’d like to be, that it’s inevitable that sometimes you’ll feel flat, crushed by the weight of your own delirious hopes and expectations. This might be called a mood-swing, a symptom of depression, or even of bipolar disorder. All effort to climb that mighty mountain seems fruitless. The very thought of it sends you back to bed.

Such moods have overtaken me many times, but I’ve never called myself depressed, at least not in a clinical sense, and never sought medical advice or taken anti-depressant medication. I’ve occasionally been pressured to do so, because misery likes company, but I have a kind of basic stoicism which knows these moods will pass and that I should ‘rise above myself and grasp the world’ – a quote said to be from Archimedes, which is the new subtitle of my blog. 

The point here is that I think I have a sense of where all this depression is coming from, and it’s not just about a lack of connection. Nor is it, surely, all about low serotonin levels, or receptor malfunctions or other purely chemical causes. It’s so much more complicated than that. That’s to say it’s about all of these things but also about failure, the gap between the ideal and the real, the gap – in advanced countries – between the privileged rich and the disadvantaged poor, disillusionment, stress, grief, selfishness, the hope deferred that makes the heart sick…

So – back to DBS. Presumably this and other treatments have the same measure of success, which might be described as ‘improved functionality within the wider world’. Being able to hold down a job, hold a conversation, hold on to your partner, hold a baby without dropping it, etc. Of course, this is a worthwhile aim of any treatment, but what is actually happening to the brain under such a treatment? Neurologists might one day be able to describe this effectively in terms of dopamine levels and electrical activity, and the stimulation or becalming of regions of the nucleus accumbens and so forth, but on the level of thinking, dreaming, wondering, all those terms studiously avoided, or just ignored, by neurology (all for understandable reasons), what is happening? We don’t know. Treatment seems essentially a matter of dealing with functionality in the external world, and letting that inner world take care of itself. Is that the right approach? Something gained, but something lost? I really don’t know. 

Written by stewart henderson

December 18, 2018 at 2:27 pm