Biotech Medibio’s depression-detecting algorithm can work out, with about 70 per cent accuracy, whether you’re just a bit down or suffering from the black dog.

A clinical trial of 230 patients in the US and Australia showed the mental health researcher’s algorithm was a 20 to 40 per cent improvement on the current diagnostic method.

Medibio (ASX:MEB) has developed an app that works with a device, worn on the wrist during sleep, that measures circadian heart rhythm and sleep cycles.

It’s based on research started by the University of Western Australia 15 years ago that suggested mental state is linked to the autonomic nervous system, circadian rhythms and sleep disturbance.

Medibio says changes in these metrics indicate different kinds of mental illness, from depression to anxiety and post-traumatic stress disorder.

The current system to determine if a person is suffering from a depressive episode is a six to nine question list asked by a doctor, who uses that to determine whether a person is suffering from a mental health episode and if so, which drugs to prescribe.

The trial could distinguish between people suffering what they called a major depressive episode and non-depressed controls with 70 per cent accuracy, 70 per cent sensitivity and 71 per cent specificity.

Sensitivity is the extent to which actual positives are not overlooked (so false negatives are few), and specificity is the extent to which actual negatives are classified (so false positives are few).

The latest results are lower than a test in 2016 which saw an accuracy rate of 86 per cent over 889 patients.

The company’s shares fell 11 per cent by midday on Thursday, to 12.5c.

Medibio shares over the last 12 months.

The stock has been under pressure by shareholders impatient to see an application to the powerful US Food and Drug Administration (FDA) for use as a clinical tool.

That happened in July and the share price rose.

The company received European approvals in May.

It was knocked back again at the end of August with the sudden and unexpected departure of high-flying CEO Jack Cosentino, an ex-Impedimed (ASX:IPD) executive only hired in February last year.

At the time, chairman Chris Indemaur said the board was unanimous in its support of Mr Cosentino’s departure and of interim CEO Brian Mower.

He was at pains to point out that the change at the top had no impact on the company’s technology, strategy or operations.

Mr Indemaur told Stockhead they are running a search for a new CEO.

“I hope that Brian is a candidate, he’s a great guy. I have absolute confidence in Brian, but we will do a search for a new CEO,” he said.