What your eyes can tell

A common saying refers to the power of the eyes as a window inside our souls; interestingly, our eyes could also be a window into our brains, helping identify certain neurological conditions like attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder (ASD).

Recent work published in Frontiers in Neuroscience ¹ found distinct electrical recording signatures in the eyes of people with ADHD or ASD, and could potentially serve as a future biomarker for these conditions.

The researchers performed electroretinograms (ERG) in 55 people with ASD, 15 with ADHD, and 156 control individuals, wherein they measured the responses of different types of cells in the retina to a light stimulus. The data was then analysed by a discrete wavelet transform approach to extract the variables of interest, like the energy or amplitude of the responses.

When comparing the responses obtained in the three experimental groups, Paul Constable and colleagues found differences in the size and pattern of responses between controls and people with ASD–decreased oscillatory potential energy– or ADHD –increased oscillatory potential energy–, thus supporting the potential of using these electrical responses as differential diagnostic tool.

Obviously, the above interpretation of results is an oversimplification. Despite the complexity of the discrete wavelet transform analysis, it allows a better characterisation of the clinical waveforms which characterise otherwise clinically similar neurodevelopmental conditions such as AHD and ASD.

What’s more is that this approach might be useful for other neurological diseases like schizophrenia or bipolar disorder, or even for neurodegenerative disease hard to distinguish based on symptoms alone like Alzheimer’s disease or dementia. Based on this research, in the future, the eyes may serve as a first approach to identify neurological conditions easily and non-invasively.