I was surprised today to learn that Alois Alzheimer – the man who discovered neurofibrillary tangles and amyloid plaques in dementia, hallmarks of the condition now known as Alzheimer’s disease – was not a neurologist, but rather a psychiatrist who fancied some neuropathology.

Neurology and psychiatry, while both dealing with the brain, are vastly different in practice. Neurology is in principle a biological specialty, where conditions have organic pathologies attributable to genetics, blood markers or other measurable disturbances. Psychiatric conditions on the other hand, have no lesions or neural abnormalities that distinguish them from normal people. The brains of patients with schizophrenia, mania or depression aren’t obviously different from those without these conditions. These are often referred to as invisible conditions of the mind.

So a psychiatrist studying post mortem brains was, as you can imagine, odd. Yet Dr Alzheimer, with the help of fellow neuropathology enthusiast Franz Nissl, persevered in his lab work and in 1906 discovered the signature of the dementia that he had been working on. To this day, neurofibrillary tangles and amyloid plaques remain key hallmarks in Alzheimer’s disease – one of the only psychiatric conditions found to have an attributable biological cause.

Alzheimer’s research motto was, quite fittingly:

“Excessive reservations and paralysing despondency have not helped the sciences to advance nor are they helping them to advance, but a healthy optimism that cheerfully searches for new ways to understand, as it is convinced that it will be possible to find them.”