Functional Brain Imaging as a Psychiatric Diagnostic Tool
Psychiatry is the only speciality in medicine that does not directly assess the organ it measures.
Cardiologists measure the heart but psychiatrists do not measure the brain. Although structural brain imagining like CT and MRI have little to offer on the whole, functional brain imaging like qEEG, fNIRS and SPECT can provide great insight into abnormalities in brain firing and blood flow. Research has for years identified objective biomarkers on brain imagining that underlies certain symptoms. There is however strong criticism against this, with some stating that it does not add much to treatment outcomes, but I would postulate that functional imagining one day will be the best way to determine appropriate treatments, and as our understanding and technology develops, will be the only objective way to understand the causes of the symptoms clusters that we call psychiatric disorders.
Psychiatric disorders are diagnosed in Australia (and the US and many other countries) by various symptom checklists. If you have enough of a certain amount of symptoms you can be diagnosed, if you fall short of 1 symptom, you can't. Mental issues such as major depression, generalised anxiety, ADHD, autism spectrum do not exist currently in any objective manner- the symptoms were decided upon by a group of psychiatrists in Amercia. This doesn't mean that these disorders don't exist, they certainly do, just not in the way we think. In the latest revision of the DSM-5 a few years ago they removed the disorder 'Aspergers' and replaced it with 'Autism Spectrum Disorder'. If Aspergers was an objective disorder, it would technically be impossible to make it disappear in a puff of smoke. Immediately following the DSM-5 release it was no longer acceptable to diagnose Aspergers. Having an objective way of diagnosing mental health and psychiatric disorders has been a major undertaking in research. We know the brain structures, neurotransmitters and electrical firing in the brains of people with mental health issues are very different to people without these disorders, so wouldn't it make sense to create a way to measure the brain directly and diagnose a brain-based issue, having the symptoms of depression, inattention, anxiety or any of the other myriad of mood, behavioural, cognitive or social issue as secondary.
Why do I think this would be helpful? Firstly, I think the patients have a right to know what is going on in their brain. If a patient has poor blood flow to their right prefrontal lobe, excess slow wave (delta & theta) frontally, and low levels of serotonin, this is the best possible insight we can have to direct therapy. Ever seen a GP or psychiatrist prescribe an anti-depressant? How to do think they make their decisions? Is there a guide to say who should receive which of the dozens or medications available? Psychiatry with medication is currently trial and error. It is based on the preferences of the psychiatrist or GP, not on any hard data. Psychiatry needs to do better in regards to patient care. If you examine the statistics of the efficacy of anti-depressants the results will shock you. Meta-analyses show that they only tend to have around 30% benefit above placebo. Yet go to a psychiatrist or GP and this is their first line treatment.
Functional imaging provides a means of directly assessing the brain, the organ of issue, and determining whether there are any areas of dysregulation or poor functioning. The next evolution of psychiatric practice should, or will, include biologically informed approaches to prognosis and diagnosis. The ability to measure mental state from the brain rather than infer through signs and symptoms would likely transform the practice to align it with known, underlying neurophysiology. As there is massive heterogeneity in psychiatric symtpoms even within a single disorder, brain imagining will allow us to better understand the etiology and allow us to optimise tretament using principles of personalised medicine, treating each person as an individual according to underlying cause, not just a broad label.
Neuroimaging that is showing promise includes:
- electroencephalography (EEG)
- magnetoencephalography (MEG)
- positron emission tomography (PET)
- functional magnetic resonance imaging (fMRI)
- functional near infrared spectroscopy
The promise of these imaging techniques has been evident from the earliest days, and yet clinical application has lagged behind, having been met with a host of valid concerns: (1) What is the specificity and sensitivity of any brain-based measure of a psychiatric state or trait feature? (2) What are the relative costs of employing neuroimaging to inform diagnostic or prognostic evaluation, and what is the evidence for a favorable cost-benefit ratio, relative to treatment as usual? (3) How well does a brain-based measure generalise across disease diagnoses?
Brilliant work is being done by many researchers. In particular the work by Juri Kroptov in biomarkers of psychiatric illness is ground breaking in his use of EEG, qEEG and ERP, and well worth looking into.
Implications for therapy & treatment?
Neuroimaging in psychiatry is not just about diagnosis and prognosis. Another avenue is the ability to use neuroimaging-based biofeedback such as EEG biofeedback and real-time functional MRI (RT-fMRI). In these therapies signals from a person's brain can be processed on the fly and delivered back to them, as a way of actually treating people with a mental illness. In general, this method of “neurofeedback” therapy involves training a person to learn to regulate brain activity, typically in a brain region or a network of regions, based on visual or auditory feedback of the current brain state of the person. Clinical trials have used neurofeedback to address ADHD, autism spectrum disorder, anxiety, epilepsy, trauma, PTSD, and major depressive disorder. Whilst EEG biofeedback has had decades of research in regards to ADHD and has even been accepted as having the highest level of efficacy by the American Academy of Paediatrics, research into other areas is relatively newer. The response from early research is encouraging, but much more needs to be understood about the different protocols used, sensor placement and style of neurofeedback. There are many styles of 'pseudo-neurofeedback' using cheap, nonclinical grade equipment, which has diluted some of the findings. It is important to make sure that proper, clinical grade equipment is used, not cheap gaming products that cost $300-$500 and can be purchased by the public. It is not really a question of whether neurofeedback works, it is more a question about getting good research into which styles of neurofeedback work best for different disorders, where should sensors be placed to train certain brain pathways, and what are the optimal parameters to get the best out of treatment.
Multi-level models of assessment
Psychiatric and cognitive illnesses are complex. No single modality, whether genomics, neuroimaging, neuropsychological assessments, or other forms of phenotyping (eg, wearables, voice, and language) is likely to provide robust markers of disease or pathways to treatment. We need to start to integrate genomics, brain imaging, neuropsychological testing, and other digital phenotyping to create as complete a picture as possible. This integration will require new technologies and models to be developed and validated, with cooperation at a global scale. Neuroimaging offers an unprecedented opportunity to move beyond classical diagnoses and improve prognosis. Neuroimaging can help create a set of neurophysiological derived subtypes that respond better to specific treatment modalities and can actually provide a basis for a direct therapeutic role using treatment such as neurofeedback. As the future of psychiatry moves towards personalised medicine, I expect neuroimaging tools to emerge as playing a key role in directing treatment options, hopefully leading to stopping the current global epidemic of depression and declining mental health, and improving quality of life and prognosis.