LONDON - A blood test could detect a range of brain disorders before serious symptoms strike, research suggests.

Dementia – an umbrella term for a loss of brain function, with Alzheimer's being the most common form of the disease – has no set diagnostic test, with medics assessing suspected patients via memory analyses, mental-agility evaluations and brain scans.

While the memory-robbing disease is considered incurable, treatments can temporarily ease symptoms, with these being more effective when administered early in dementia's onset.

The concept of a blood test to detect brain disorders is not new, with past studies suggesting biomarkers circulate in a patient's blood before they develop symptoms of a particular disease.

After analysing the blood samples of more than 3,000 people, scientists from King's College London found a single biomarker could pick up on diseases like dementia in people with mild "cognitive issues" with up to 100% accuracy.

Detecting conditions "when clinical symptoms are not definitive" could help to avoid misdiagnosis, with dementia often being confused for depression in its early stages.

"For the first time we have shown across a number of disorders that a single biomarker can indicate the presence of underlying neurodegeneration with excellent accuracy," said study author Dr Abdul Hye.

"Though it is not specific for any one disorder, it could help in services such as memory clinics as a rapid screening tool to identify whether memory, thinking or psychiatric problems are a result of neurodegeneration."

Neurodegeneration is another umbrella term for a range of diseases caused by a progressive loss of nerve cells in the brain, affecting a person's memory, attention span and thinking skills.

Biomarkers can be taken from the cerebrospinal fluid that surrounds the brain and spine, but this has to be extracted via an invasive procedure.