• Clinical neurology
• Creutzfeldt–Jakob disease
• B₁₂ deficiency
• prion
• Alzheimer's disease

While taking the history from a patient with possible cognitive impairment, ‘the physician may observe that the patient exhibits the head turning sign (looking at his care-giver when asked a question), which is a common sign in A[lzheimer's] D[isease]’.1 NHS Evidence Clinical Knowledge Summary advises that the diagnosis of dementia be suspected ‘if, when you ask the person a simple question, they immediately turn to their partner — the so-called head-turning sign’.2 But how common is the head turning sign (HTS), and how useful is it in diagnosis? A prospective observational study of day-to-day clinical practice in a memory disorders clinic was undertaken to examine these questions.

HTS was operationalised thus: following introductions and initial pleasantries, HTS was adjudged to be present (HTS+) if the patient turned her/his head away from the interlocutor and towards the accompanying person(s) when first invited to describe symptoms (eg, ‘Tell me about the problems you are having with your memory’) or when specifically asked about them (eg, ‘What …