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Cognitive Disorders

Checked: 09-06-2023 by 5 Rob Adams Next Review: 08-06-2025


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

What to do before referral

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.

Neurology Advice and Guidance

They neurology advice and guidance service (available via eRS) can be useful if you have concerns about a patient and are unsure how to further investigate or refer.

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: 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. For patients with historical head injury then see section below.

Other considerations

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

Cognitive impairment and any history of head Injury/ traumatic brain injury

  • Recent Head Injury - Adult patients aged 16 years and over, within 1 year of concussion/ mild traumatic brain injury. See the Concussion / mild traumatic brain injury page.
  • Historic single or multiple head injuries - Patients with new cognitive symptoms following a previous history of head injury should be referred to Cognitive Neurology clinic via eRS.
  • Older patients with very distant historic head injury - Patients presenting in later life with symptoms more typical of demenia and where other referral criteria are met can be referred to dementia services. See the Dementia Assessment and Referral page.
  • Psychiatric problems caused by acquired brain injury - There is a neuropsychiatry service for patients with neuropsychiatric problems caused by acquired brain injury. This is available via a RAS. See the Neuropsychiatry page for details.
  • Patients previously under care of neurology - In general if a patient has been seen by a neurology service for an acquired impairment in the past, they should be referred back to that service in the first instance if there concerns around new cognitive decline.
  • Brain injury rehab is via the Frenchay Brain Injury service.

Driving Guidance

For any patient assessed in primary care in whom there is a concern about cognitive impairment or dementia, it is the responsibility of the assessing clinician to give advice in line with DVLA guidance. This should be addressed prior to referral to secondary services.Please see link to DVLA guidance below:

Psychiatric disorders: assessing fitness to drive - GOV.UK (

The British Geriatrics Society provide further practical information to assist in assessment if required.

Driving with Dementia or Mild Cognitive Impairment - Consensus Guidelines for Clinicians

 Other resources:


Referral should be considered after assessment and investigation in primary care as above and according to suspected cause.

Cognitive Neurology (NBT Cognitive Disorders Clinic) via eRS

The cognitive disorders clinic at NBT is a specialised service for adults with suspected neurodegenerative cognitive disorders, in particular young onset and atypical presentation cognitive disorders (eg: language, visuospatial variants).  They also offer a tertiary service to patients who have been through local memory services or cognitive clinics outside Bristol for whom a second referral is appropriate.

Driving status must also be discussed with the patient prior to referral (1)


  • Primary problem is related to chronic fatigue, chronic pain/fibromyalgia, alcohol or other addiction, untreated or significant anxiety or depression. 
  • Patients with traumatic brain injury unless historical and a new neurodegenerative disorder is under consideration. 
  • Assessment for ADHD or learning disabilities.  People with learning disabilities with suspected dementia should be referred to a psychiatrist with expertise in assessing and treating mental health problems in people with learning disabilities.
  • Suspected encephalitis (rapid onset cognitive decline) - please refer to the general neurological service.
  • Suspected Normal Pressure Hydrocephalus should be referred to Neurosurgery
  • They do not operate an emergency service

Procedures performed

A combination of neuropsychology, neuroimaging (CT/MRI/PET – FDG and Amyloid) and CSF analysis is used to give accurate biomarker based diagnosis.  A significant proportion of patients will have genetic testing.

Neurosurgery via eRS RAS

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

Sleep Apnoea is associated with cognitive impairment, increases the risk of dementia and may accelerate the onset of Alzheimer’s in a reversible fashion.Sleep Apnoea should be ruled out before considering dementia, particularly in younger populations and cognitive impairment may be due to a treatable condition.

See the  Obstructive Sleep Apnoea page for details on assessment (including STOP-Bang and Epworth Sleepiness scale) and referral.

Dementia Wellbeing Services

Referrals to the Dementia Wellbeing Services should only be made if dementia is likely, 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.


See the Neuropsychiatry page for information and referral criteria for the Functional Neurology Service and the complications of acquired brain injury.


Cognitive impairment and Driving

(1) Psychiatric disorders: assessing fitness to drive - GOV.UK (

Tools for assessment:

Efforts are made to ensure the accuracy and agreement of these guidelines, including any content uploaded, referred to or linked to from the system. However, BNSSG ICB cannot guarantee this. This guidance does not override the individual responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and/or guardian or carer, in accordance with the mental capacity act, and informed by the summary of product characteristics of any drugs they are considering. Practitioners are required to perform their duties in accordance with the law and their regulators and nothing in this guidance should be interpreted in a way that would be inconsistent with compliance with those duties.

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