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Dementia: History Taking and Differential Diagnoses

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History Taking

Introduction

The assessment and diagnosis of dementia should be based on the comparison of the current patient’s cognitive and functional abilities with their premorbid level.

It may be necessary to take a collateral history alongside the patient (e.g. from a family member or carer). In this case, ensure to confirm the representative’s name and relation to the patient, and remember to ask the patient themselves if they are happy for the representative to speak on their behalf and be there with them.

Overview

With each symptom, always (if relevant) ask about:

  • When did it start?
  • Did it come on suddenly or gradually?
  • Is it continuous or intermittent?
  • Has this ever happened before?

Dementia

  • Duration – how long as this been going on?
  • Onset:
    • Was it sudden?
    • Over how long did this start?
    • What were they like before it started?
    • Are they and were they independent?
  • How has it progressed?
  • Ask about psychiatric symptoms:
    • Are there any hallucinations?
    • Are there any delusions? (e.g. persecutory delusions)
  • Ask about sleep:
    • Are they awake at night?
    • Do they wake up early in the morning – suggests depression
    • Is there fluctuating consciousness – suggests delirium
  • Ask about specific cognitive disturbances:
    • Problems with speech?
    • Problems with coordination?
    • Problems with recognising things or faces?
    • Difficulties with planning, organising, and decision-making?
  • Screen for possible triggers – PINCHMME:
    • Pain
    • Infection (particularly urinary tract infections, pneumonia, sepsis)
    • Nutrition – have they been eating?
    • Constipation and urinary incontinence – how are their bowels and bladder?
    • Hydration – are they dehydrated?
    • Medications – what medication do they take?
      • Have there been any new ones started or old ones stopped?
      • Have any doses been changed?
      • Sedatives, anticholinergics, alcohol, tricyclic antidepressant overdoses, anti-Parkinsonism medications, corticosteroids
    • Metabolic – hypoglycaemia, electrolyte disturbances, B vitamin deficiencies
    • Environment – changes in the environment can commonly precipitate delirium
  • Assess the patient’s risk.
    • To self:
      • Have they been wandering?
      • Are they leaving the cooker on?
      • Are they self-neglecting?
      • Do they feel worthlessness or guilt?
      • Do they think of death or self-harm?
    • To others:
      • Are they aggressive?
      • Are they carrying out any risky behaviours?
  • Ask about the carer:
    • Are they stressed?
    • Are they coping?
    • Do they have support?

Impact

  • Does it stop them from carrying out their normal activities?
  • Are they able to dress, get around the house, and go to the shop?
  • Do they have carers come into their home?

Review of systems

  • Screen for general red flags:
    • Any fever?
    • Any night sweats?
    • Any unexplained weight loss?
    • Any symptoms associated with a stroke? Examples are:
      • Problems with balance?
      • Problems with speech?
      • Weakness or numbness?
  • Screen for neurological symptoms:

Past Medical History

Questions include:

  • Do they have any other medical conditions? Some conditions to explore are:
  • Have they ever had any previous surgery?
  • Do they take any regular medications?
  • Do they take any over-the-counter medications, herbal remedies, or supplements?

Family History

  • Is there any family history of anything similar?
    • Any history of dementia, vascular disease, or depression?

Allergy History

  • Are they allergic to anything?
    • What happens during the allergic reaction?

Social History

  • Do they smoke?
    • If so, how much and how long?
  • Do they drink alcohol?
    • If so, how much and how long?
  • Do they use any illicit drugs?
    • If so, how much and how long?
  • What is/was their occupation?
  • Who’s at home?
    • What support do they have?
  • How has this impacted their activities of daily living?

Physical Examinations

Overview

Neurological signs:

Cardiovascular signs:

  • Hypertension
  • Arrhythmia
  • Peripheral vascular disease

Other:

  • Psychiatric evaluation
  • Signs of physical illness e.g. head trauma

Investigations

Screening tools

Cognitive assessment tools in a non-specialist setting include:

  • 10-point Cognitive Screener (10-CS)
  • 6-item Cognitive Impairment Test (6-CIT)
  • 6-item Screener
  • Memory Impairment Screen (MIS)
  • Mini-Cog
  • Test Your Memory (TYM)

Dementia should not be ruled out solely based on a normal cognitive assessment test.

Initial investigations in primary care

Initial investigations are to rule out possible reversible causes of symptoms:

Other investigations may need to be considered if appropriate:

  • Chest x-ray
  • ECG
  • Urine microscopy and culture
  • Urine toxicology panel for opiates, cocaine, benzodiazepine and cannabinoids
  • Syphilis serology
  • HIV testing

Referral to secondary care

If the person is severely disturbed, arrange admission to hospital. Detention under the Mental Health Act (1983) may be needed.

If dementia is suspected in people with learning disabilities arrange a specialist referral for assessment and treatment.

People with MCI are followed up regularly and referred to secondary care if their symptoms deteriorate.

All other patients should be referred to a memory assessment service for specialist assessment and management.

Investigations in secondary care

Specialist investigations involve neuroimaging to screen for reversible structural causes (e.g. subdural haematoma). These may include:

  • MRI head
  • CT head

Other specialist tests are performed to help diagnose a dementia subtype and know more about the dementia subtype and adjust management:

  • Fluorodeoxyglucose-positron emission tomography-CT (FDG-PET):
    • Shows reduced glucose uptake in regions of the brain that are affected by dementia
  • Perfusion SPECT (single-photon emission CT):
    • Shows decreased perfusion in the regions of the brain that are affected by dementia
  • Cerebrospinal fluid examination:
    • This involves examining for tau and amyloid which suggest Alzheimer’s disease as the aetiology of dementia

Differential Diagnoses

Alzheimer’s disease

  • A history may reveal:
    • Insidious and slow progression
    • Memory loss is the first symptom and predominates.
      • Short-term memory loss is affected more than long-term
    • Disorientation in time and place
    • Difficulty naming objects or people
  • Investigations may reveal:
    • As discussed above, further investigations after testing for reversible causes include:
      • MRI/CT head:
        • Cerebral atrophy including the hippocampus and medial temporal lobe
      • Fluorodeoxyglucose-positron emission tomography-CT (FDG-PET):
        • Shows reduced glucose uptake in regions of the brain that are affected by dementia
      • Perfusion SPECT (single-photon emission CT):
        • Shows decreased perfusion of the temporal lobes
      • Cerebrospinal fluid examination:
        • This involves examining for tau and amyloid which suggest Alzheimer’s disease as the aetiology of dementia

Vascular dementia

  • A history may reveal:
    • Stepwise decline of symptoms
    • There may be a history of stroke or transient ischaemic attack
    • There may be risk factors for cardiovascular disease
    • There may be associated neurological symptoms (e.g. hemiparesis)
    • There may be associated labile mood
  • Investigations may reveal:
    • As discussed above, further investigations after testing for reversible causes include:

Dementia with Lewy bodies

  • A history may reveal:
    • Fluctuating cognition (e.g. swings between being alert, confused, or drowsy). This can occur over minutes to hours.
    • Well-formed, vivid hallucinations
    • Features of Parkinsonism emerge after dementia 
  • Investigations may reveal:
    • Discussed above, further investigations after testing for reversible causes include:
    • MRI/CT head:
      • To screen for other causes (e.g. subdural haematoma, brain tumours)
    • Single-photon emission computed tomography (SPECT):
      • Also known as a DaTscan
      • Identifies low basal ganglia dopamine transporter uptake

Frontotemporal dementia

  • A history may reveal:
    • Disinhibition, inappropriate social/sexual behaviour, withdrawal, apathy, risk-seeking behaviours
    • Memory is relatively preserved 
  • Investigations may reveal:
    • Discussed above, further investigations after testing for reversible causes include:
      • CT/MRI:
        • Atrophy of the frontal and temporal lobes

Mild cognitive impairment

  • A history may reveal:
    • Minor memory problems and other features of cognitive impairment that do not interfere with activities of daily living or have a minimal effect

Delirium

  • A history may reveal:
    • Acute, fluctuating consciousness, cognition, and perception developing over hours to days
    • Behavioural disturbances, disorganised thinking, paranoia, hallucinations, and emotional disturbances may be present
    • There may be a trigger (e.g. pain, infection, nutritional problems or dehydration, constipation or urinary retention etc.)
  • Investigations may reveal:
    • Cognitive assessment:
      • Delirium can be diagnosed with CAM, DSM-V, or 4AT
    • Further investigations are to identify an underlying cause, see Delirium.

Depression

  • A history may reveal:
    • Persistent, pervasive low mood, anhedonia, poor concentration, poor sleep, poor appetite, lethargy
    • Feelings of worthlessness, guilt, thoughts of death, hopelessness for the future
    • Memory may be affected but recognition memory preserved
    • Suicidal ideation and thoughts of self-harm may be present

Stroke

  • A history and physical exam may reveal:
    • FAST features – facial drooping, arm/leg weakness, speech problems
    • Speech problems may include impaired comprehension and/or fluency depending on if the lesion is in Wernicke’s area or Broca’s area. Read more about aphasia here
    • Numbness, tingling, vision loss, loss of coordination, loss of balance
  • Investigations may reveal:

Parkinson’s disease dementia (PDD)

  • The cardinal features of Parkinson’s disease precede dementia in PDD, whereas in dementia with Lewy bodies, dementia occurs first, followed by Parkinsonism
  • A history and physical exam may reveal:
    • TRAP features:
      • Tremors
      • Rigidity
      • Akinesia/bradykinesia
      • Postural instability
  • Parkinson’s disease is clinically diagnosed by a specialist

Huntington’s disease (HD)

  • A history and physical examination may reveal:
    • Involuntary movements (chorea)
    • Personality changes
    • Intellectual impairment
    • Abnormal eye movements

Brain tumour

  • A history and physical examination may reveal:
  • Investigations may reveal:
    • CT/MRI head:
      • Identifies lesion

Subdural haematoma

  • A history may reveal:
    • May be chronic – weeks to months of confusion, reduced consciousness, or neurological defects, or acute – symptoms present more acutely
    • There may be a history of head trauma in the fall and/or anticoagulant use
  • A physical exam may reveal:
    • Reduced consciousness following the fall or head trauma, focal neurological signs depending on where the haematoma is
  • Investigations may reveal:
    • CT head:
      • Shows a crescenteric collection that is not limited by the suture lines
        • If acute, it is hyperdense, if chronic, it is hypodense

Hypothyroidism

  • A history and physical examination may reveal:
    • Fatigue, cold intolerance, dry skin, weight gain, constipation, low mood, weakness, dry skin
  • Investigations may reveal:
    • Thyroid function tests (TFTs):
      • Elevated TSH and low T3 and T4

Neurosyphilis

  • A history and physical exam may reveal:
  • Investigations may reveal:
    • Syphilis testing is positive

Normal pressure hydrocephalus

  • A history and physical exam may reveal:
    • A triad of:
      • Dementia
      • Gait problems
      • Urinary incontinence
  • Investigations may reveal:
    • CT head/MRI head:
      • Screens for mass lesions before considering a lumbar puncture
      • Shows ventriculomegaly

Creutzfeldt-Jakob disease

  • A history and physical exam may reveal:
    • Rapidly progressing dementia: memory loss, personality changes, hallucination
    • Ataxia, myoclonus, Parkinsonism, chorea

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