36 HOW TO TREAT : YOUNG-ONSET DEMENTIA
36 HOW TO TREAT : YOUNG-ONSET DEMENTIA
4 AUGUST 2023 ausdoc . com . au
Box 1 . Red flags for youngonset dementia
• A new-onset psychiatric presentation in someone middle aged with no previous
24 , 25 psychiatric history .
• Behaviour changes inconsistent with an individual ’ s previous personality . 4
• Progressive neurological symptoms . 4
• Cognitive / behavioural / psychiatric changes in someone where there is a family history of young-onset dementia . 4
medication . Because dementia is not expected in younger people , it makes sense to treat presenting symptoms . Red flags for young-onset dementia appear in box 1 .
The overlap between psychiatric disorders and young-onset dementia is highlighted by the most common genetic cause of FTD , the C9orf72 mutation . 26 This presents with behavioural-variant frontotemporal dementia ( bvFTD ), motor neuron disease , a combination of both , and psychiatric symptoms . The latter may be longstanding , of up to two decades . 27
A 2019 scoping review noted the absence of clinical guidelines for assessment of young-onset dementia , resulting in the 2020 Delphi study for consensus criteria for assessment of
18 , 28 young-onset dementia .
Table 1 lists elements of a history and examination to assess for young-onset dementia . Note that bvFTD has symptoms that may be mistaken as a psychiatric disorder , such as depression or mania ; up to 50 % of individuals eventually diagnosed with bvFTD have a previous diagnosis of a psychiatric disorder . 17 , 24 , 25 , 29 A 2020 publication reviews this and makes recommendations for differentiating between bvFTD and psychiatric disorders . 17 Table 2 lists some distinguishing factors that may guide appropriate referral .
Emerging technologies show promise for differentiating young-onset dementia and psychiatric disorders . These include neurofilament light chain ( NfL , see figure 1 , Dr D Eratne , unpublished ), and amyloid specific PET scans that indicate AD , and tau PET . 30 , 31 Tau PET binds to tau proteins in neurofibrillary tangles but this is not specific for AD and may be present in other tau-related conditions ( tauopathies ) such as progressive supranuclear palsy and chronic traumatic encephalopathy .
Some groups recommend using behaviour rating scales such as Frontal Assessment Battery or Neuropsychiatric Inventory , but these are not systematically reviewed
17 , 28
.
DIAGNOSIS
BECAUSE of the difficulty recognising dementia in younger people , it may take 4-5 years to make a diagnosis of young-onset dementia , longer than it takes to diagnose older-onset dementia , with diagnostic delay the norm ,
21 , 32-34 rather than the exception .
Young-onset dementia occurs at a time of high occupational , financial and familial responsibilities . 4 Multiple stressors are common during this busy period ; it is not unusual for patients presenting to their GP with symptoms of depression or anxiety to be told the symptoms are due to stress , lack of sleep or similar . 35 They may then often
Table 1 . Critical elements for assessment of young-onset dementia and red flags Assessment History taking
Collateral history
Family history Psychiatric history
Risk factors
Physical and neurological examination
Detail
be referred to the relevant healthcare professional , which might add to diagnostic delay .
Lack of responsiveness or minimal improvement with psychotherapy or counselling or to psychotropic medications warrants further investigation . Worsening or non-responsive symptoms can cause additional distress to
Guided structured approach Time course of illness Pattern of physical , neurological , cognitive and behavioural symptoms Importance of collateral history Crucial
Presence of stereotypical , ritualistic behaviours ; preference for sweet foods ; increased weight gain ; poor social awareness ; lack of empathy ; other behaviours
Psychiatric , neurological or neurodegenerative disease in first- and second-degree relatives Onset and type Absent to minimal previous psychiatric history and symptoms
Absence of first rank symptoms ( eg , passivity phenomenon , command auditory hallucinations , running commentary or conversing voices ) may indicate neurodegeneration
Hypo / manic symptoms such as disinhibition , lack of awareness , obsessive compulsive traits can be mistaken for symptoms of FTD
Depressive symptoms such as anhedonia , amotivation , social withdrawal , lack of initiation and apathy can be mistaken for symptoms of FTD
Traumatic brain injury , developmental disability , autism spectrum disorder , alcoholic misuse To investigate signs that may indicate FTD
Parkinsonism – bradykinesia , rigidity , tremor , asymmetry of signs Frontal release signs – grasp , palmomental reflexes Eye signs such as vertical gaze palsy , saccadic interruptions , nystagmus Apraxia Upper motor neuron signs – hyper-reflexia , clonus , spasticity Lower motor neuron signs – weakness , atrophy , fasciculations Bedside cognitive tests Montreal Cognitive Assessment ( MOCA )
Neuropsychology
Investigations
Addenbrooke ’ s Cognitive Examination ( not usually administered by the GP ) Neuropsychiatry Cognitive Assessment Screening Tool
Include social cognition tests that assess the ability to detect other people ’ s emotions and how to respond appropriately
Structural neuroimaging – MRI Functional neuroimaging – PET Cerebrospinal fluid ( CSF ) examination for Alzheimer ’ s-related proteins of amyloid-beta and tau
Table 2 . Factors that may distinguish between psychiatric and neurodegenerative disorders in younger people
Factor Psychiatric disorders Neurodegeneration Onset / history
Family history
Neurological examination
‘ Long standing ’ ( ie , onset in late adolescence or early adulthood )
Parkinsonism possibly due to side effects of psychotropic medications
the individual and their family . Individuals may see 3-5 other specialists before receiving a diagnosis of dementia , after repeating their story , feeling they are not believed and undergoing multiple investigations and assessments . 32
Time lags of up to 19 months from primary care to the specialist
‘ Recent ’ ( ie , within 10 years )
Psychiatric , neurological or neurodegeneration disorders in family might indicate a risk for young-onset dementia
Parkinsonism – less tremor ; more bradykinesia , gait changes and rigidity
Oculomotor / eye changes Upper motor neuron signs
Primitive reflexes / frontal release signs such as grasp , suck or palmomental response
Lower motor neuron signs Dysarthria Dysphagia
Bedside testing May not be able to discriminate May not be able to discriminate
Recommend further testing ( ie , neuropsychology + social cognition tasks )
Recommend further testing ( ie , neuropsychology + social cognition tasks )
have been reported , with a further 18 months ’ delay within the hospital system . 21
Access to appropriate investigations may be challenging . Bedside cognitive testing is the first-line assessment in primary care . The Mini-Mental State Examination lacks sensitivity in most people with young-onset dementia , with the Montreal Cognitive Assessment , Addenbrooke ’ s Cognitive Examination III ( ACE-III ) and Neuropsychiatry Cognitive Screening Tool having better sensitivity . 17 , 18 , 36 , 37 It is worth booking a longer appointment for these assessments or having a practice nurse perform them .
Neuroimaging in the form of MRI where possible , can be informative . 18 However , access is limited ( especially in rural and regional areas ), scans may be reported as normal in the presence of disease , and they are costly ( up to $ 1500 ). 21 If a patient can afford out-of-pocket costs for an MRI , useful information on the referral form includes a relevant clinical history (“ 55-year-old man with family history of young-onset dementia presents with gradual onset short-term memory impairment and depressed mood over 4-5 years ”) and differential diagnoses (“? Alzheimer ’ s dementia ”).
Functional neuroimaging is available on the MBS , but costs can also be prohibitive , with similar out-ofpocket costs for patients . Referral to a specialist neurologist , geriatrician or psychiatrist may assist in obtaining these investigations and with further assessment .
Cerebrospinal fluid ( CSF ) analysis via lumbar puncture can certainly assist in the diagnosis of AD but is invasive and often inaccessible ,
21 , 38 except in specialist centres .
While often targeting those over 65 , a memory or cognitive decline assessment service may also offer assessment for younger people and / or provide information about alternative services .
An earlier referral to a specialist service is thus recommended if young-onset dementia is even considered as a differential diagnosis . Such a service could offer assessment in an inpatient setting allowing access to multidisciplinary assessments ( functional , neuropsychology and social work ) and observations , access to neuroimaging ( functional and structural ), neurology and CSF analysis , and follow-up in the community . 38 Telehealth has scope to reach those in rural and regional
38 , 39 settings .
SERVICE PROVISION AND POST-DIAGNOSTIC SUPPORT
THE delivery of high-quality , holistic post-diagnosis care is of paramount importance once young-onset dementia is diagnosed . Most dementia care services are embedded in the aged care system and are designed and tailored for older people with dementia . 6 , 7 , 40
These services are not suitable for young people with dementia and their families ( particularly where they impose age-based eligibility limits ), do not provide childcare , are delivered within working hours and are expensive . 6
Services for delivery of postdiagnosis care for young people with dementia should be tailored , flexible , affordable and provide meaningful engagement . 6 Deciding which services are required depends on the patient ’ s specific impairments , disabilities and needs . At a minimum , encourage contact with Dementia Australia for access to psychoeducation and social support .
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