Cognitive Disorders (Draft)

Overview

Cognitive impairment can have many causes and may or may not he a precursor to dementia.

The following page may be helpful in acting as a guide to primary care clinicians in investigating and managing cognitive impairment. 

Not all patients with cognitive impairment will go on to develop dementia.

Patients with cognitive impairment should not be referred to the Dementia service if there are red flags or if underlying causes have not been excluded

Causes of cognitive impairment

There are many factors that may influence or impair cognition and these should be considered when assessing someone who presents with cognitive problems including:

• Cerebrovascular events.
• Hypothyroidism.
• Hyperparathyroidism, hypoparathyroidism.
• Hypoperfusion - eg, heart failure.
• Head trauma, including recurrent trauma of having been a boxer.
• Deficiencies of folate, vitamin B12 and vitamin B6 are associated with neurological and psychological dysfunction and are potential factors for cognitive impairment and the development of dementia in the elderly.^[6]
• Open heart surgery with cardiopulmonary bypass.
• Medication use, especially sedatives.
• Hepatic impairment.
• Sleep disorders - eg, obstructive sleep apnoea.
• Depression.
• Psychological stress.
• Drug or alcohol abuse.
• Toxins, infections, metabolic (eg, hypoglycaemia) and structural causes.
• Functional cognitive symptoms

Investigation

History and examination

Assessment of cognitive impairment should initially involve a detailed history, systems enquiry and examination try to establish underlying causes.

If the cognitive impairment is acute or of rapid onset then consider the Red Flag section below.

Ask particularly about:

• Changes in gait and urinary continence (possible symptoms of Normal Pressure Hydrocephalus)
• Sleep problems e.g. Obstructive sleep apnoea (OSA) can be a cause of cognitive decline - see OSA page for advice on assessment and investigation.
• History of head injury - recent or historical (subdural haemorrhage or brain injury). If recent (under one year consider - Concussion / mild traumatic brain injury. If longer then consider neurology referral.
• Mental health problems - depression, anxiety or stress can all lead to impaired cognition.
• Drug and alcohol use
• Medication use - opiates, benzodiazepines and other sedative medication can cause cognitive problems.

For more persistent or chronic cognitive impairment then further investigation in primary care can help to establish a diagnosis.

Blood tests

Blood test screening can be performed to exclude underlyling causes. The ICE profile dementia screening bloods are a good starting point but other bloods may be considered if appropriate.

Brain imaging

Brain imaging (normally CT scan) should be considered if an underyling brain pathology is suspected such as dementia, brain tumour or NPH.

Red Flags

Delirium - see CKS guidelines on Delirium

Rapid decline e.g. suggestive of encephalitis: contact the on-call neurologist or IUC professional line to discuss whether needs admission vs other referral route.

HIV positive: if the patient is not already under care of HIV services, refer to NBT HIV Specialist Nurses (email: Brecon.nurses@nhs.net) for CD4 count, Viral load and cerebral lymphoma screen in the first instance – may need referral to Cognitive Neurology after this.

Normal Pressure Hydrocephalus: rapid onset of cognitive decline which may be associated with gait abnormalities and/or urinary incontinence is suggestive of NPH. Urgent brain imaging (CT or MRI) may be suggestive of diagnosis but is not diagnostic so consider urgent referral to neurosurgeons via eRS RAS.

Obstructive Sleep Apnoea: OSA can be a reversible cause of cognitive decline so should be investigated if concerns

Head injury: If recent head injury then consider urgent imaging of brain or if more rapid decline in context of head injury then admit to ED for assessment.

Mild Cognitive Impairment

Share Dementia: Helping your brain to stay healthy leaflet aimed at patients, focusing on what dementia is and the importance of a healthy lifestyle. Discuss lifestyle considerations.

Review in 6 months

Referral

Referral should be considered according to suspected cause.

Cognitive Neurology (NBT Cognitive Disorders Clinic)

Factors indicating a referral would be appropriate for a referral to cognitive neurology via eRS include:

• Movement Disorder
• History of Seizures
• History of Significant Head Injury with additional cognitive decline since (brain injury rehab is via the Frenchay Brain Injury service).

• Very rapid decline (significant cognitive decline less than 6 months history)

Neurosurgery

Patients should be referred to neurosurgery via eRS for the following conditions:

• Normal Pressure Hydrocephalus - if suspected clinically or after imaging. Refer to Neurosurgery Hydrocephalus RAS.
• Brain tumour - benign or suspected malignant CNS tumours.

Sleep Studies

If Obstructive Sleep Apnoea is suspected then see the Remedy page for details on referral.

Dementia Services

Referrals to the Dementia Services should only be made if other causes of cognitive decline have been excluded and referral criteria are met. These services are community services and cannot treat or investigate other conditions causing cognitive impairment.

Neuropsychiatry

See the Neuropsychiatry page for information and referral criteria for the Functional Neurology Service.