Seasonal change often generates a flurry of diagnosing. It should be okay to be sad about the shortening days, rather than suffering from ‘seasonal affective disorder’. In women, a runny nose and a sore throat transforms into ‘flu’ and in men it becomes ‘manflu’.

Once a diagnosis is made it is indelible.

Escalation of symptoms to disease-like proportions is problematic for individuals. It is quite challenging to acknowledge that the diagnostic labels that have served us well for centuries are now not always fit for purpose.

Once a diagnosis is made it is indelible. One of the most dangerous areas for overdiagnosing is in mental health. Almost half of the physicians in one survey did not disclose that they had a mental illness. Fear of reporting to a medical licensing board and the belief that diagnosis was embarrassing or shameful were two of the main reasons.

Once autism, bipolar disease, ADHD and, even depression, are bestowed on a person, they can never be removed – even if these problems diminish below the threshold of clinical diagnosis. For the elderly, the problem of overdiagnosing depression is widespread. In one study, 40% of subjects aged 65–79 years were found by researchers not to suffer from depression, even though a clinician had told them they did.

Overdiagnosing is often accompanied by overinvestigating. In the last decade, the number of specialty referrals and CAT or MRI scans performed for headaches nearly doubled (from 6.7% in 2000 to 13.9% in 2010). One in three patients who had a colonoscopy ultimately were found not to need it.

Severity can also be overdiagnosed and lead to overmedication. One in four patients who received blood thinners didn’t need to be taking them and over half of all diabetic patients are treated excessively to achieve low levels of blood sugar.

Worse still is when overdiagnosis of severity and subsequent overtreatment do not lead to any improvement. Thyroid cancer is a good example. Despite the rise in diagnoses, which has tripled over the past 30 years, and subsequent increases in treatment, the death rate from thyroid cancer has remained stable.

More investment is needed in reducing overdiagnosis and overtreatment. One way would be to focus more on individual patients and less on diagnostic labelling.