Table 1 Eligibility criteria

Inclusion criteria

• Patient > 65 years old admitted to an acute medical ward

• Delirium or subsyndromal delirium within the last 48 h

• Signed informed consent from patient or relatives including advance consent for on-going treatment and follow up

Exclusion criteria

• Symptomatic bradycardia, bradycardia due to sick sinus syndrome, second- or third- degree AV-block (if not treated with pacemaker) or any other reason causing HR^a < 50 bpm^b at time of inclusion

• Symptomatic hypotension or orthostatic hypotension, or a systolic BP^c < 120 at the time of inclusion

• Ischemic stroke within the last 3 months or critical peripheral ischemia

• Acute coronary syndrome, unstable or severe coronary heart disease (symptoms at minimal physical activity; NYHA^d 3 and 4) and moderate to severe heart failure (NYHA 3 and 4). (Acute coronary syndrome is defined according to international guidelines)

• A diagnosis of polyneuropathy, phaeochromocytoma or renal insufficiency (estimated GFR^e< 30 ml/min according to the MDRD^f formula)

• Body weight < 45 kg

• Considered as moribund on admission

• Unable to take oral medications

• Current use of tricyclic antidepressants, monoamine reuptake inhibitors or cyclosporine

• Previously included in this study

• Adverse reactions to clonidine or excipients (lactose, saccharose)

• Not speaking or reading Norwegian

• Any other condition as evaluated by the treating physician

• Admitted to the intensive care unit