Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Recognise behavioural and language-led frontotemporal degeneration, distinguish it from psychiatric and Alzheimer presentations, and coordinate genetic, communication, safeguarding and multidisciplinary care.
FTD is a clinical syndrome caused by degeneration of frontal and temporal networks and heterogeneous protein pathologies, including tau and TDP-43 disease. Behavioural-variant FTD changes social conduct and motivation: tactless or impulsive acts, loss of warmth, inertia, rigid routines, repetitive movements, altered food preference and poor judgement may precede obvious memory failure. The language-led syndromes are progressive rather than stroke-like. Semantic-variant primary progressive aphasia causes fluent but empty speech, anomia and impaired single-word comprehension with loss of conceptual knowledge. Non-fluent or agrammatic PPA causes effortful, halting or grammatically simplified speech, sometimes with apraxia of speech. Logopenic PPA is commonly associated with Alzheimer pathology and should not automatically be classified as frontotemporal degeneration.
Diagnosis depends on change from the person's baseline and functional consequence. Seek collateral examples of work errors, online spending, scams, driving, eating, hygiene, sexual behaviour, empathy and language; distinguish apathy from depression by affect, distress, biological symptoms and loss of initiative. Screen medicines, alcohol, sleep, thyroid and B12 status, infection and structural disease. Formal neuropsychology can reveal executive, social-cognitive or language profiles despite a misleadingly acceptable global score. MRI assesses focal atrophy and alternative lesions; specialist functional imaging or cerebrospinal-fluid and Alzheimer biomarkers may resolve uncertain atypical cases. Psychiatric illness, autism traits, bipolar disorder and obsessive-compulsive disorder can mimic elements, but late progressive change, neurological features and worsening function require neurological evaluation.
Many cases arise without a recognised family history through progressive proteinopathy affecting frontal and anterior temporal networks, often before typical late-life dementia age.
Pathogenic variants involving C9orf72, GRN, MAPT and other genes cause a substantial familial subgroup, with variable behavioural, language, parkinsonian or motor-neurone phenotypes.
Shared TDP-related biology links some FTD syndromes with motor neurone disease, so weakness, fasciculation, bulbar change and respiratory symptoms require deliberate assessment.
Tau, TDP-related or less commonly FUS-related proteins misfold and disrupt neuronal and glial function in vulnerable networks.
Progressive synaptic failure and atrophy damage circuits governing inhibition, motivation, empathy, language meaning and speech planning.
Reduced executive control and social cognition produce disinhibition, apathy, compulsive behaviour or impaired language while episodic memory may remain superficially preserved early.
Progressive disinhibition, apathy, reduced empathy, compulsive routines, dietary change and executive failure with early relative memory sparing forms the characteristic syndrome.
Fluent speech with severe naming and single-word comprehension difficulty, plus declining knowledge of familiar people or objects, suggests semantic-variant primary progressive aphasia.
Effortful speech, distorted sound production, apraxia of speech or grammatical simplification with initially preserved word meaning suggests non-fluent or agrammatic PPA.
Fasciculation, weakness, spasticity, dysphagia, parkinsonism, apraxia or impaired vertical eye movement may reveal overlap with motor neurone or atypical parkinsonian degeneration.
Several relatives with young dementia, motor neurone disease or late psychiatric change, or onset at a particularly young age, strengthens the case for genetics referral.
Depression, bipolar illness and psychosis can alter behaviour, but steadily progressive loss of empathy, executive function or language with neurological signs supports neurodegeneration.
Early storage-memory and visuospatial failure favours Alzheimer disease; language-led or behavioural Alzheimer phenotypes still require biomarker-informed specialist distinction.
Tumour, stroke, hydrocephalus and traumatic injury may mimic frontal degeneration, particularly with abrupt, stepwise or pressure-related symptoms and focal imaging findings.
Visual hallucinations, marked fluctuation, REM sleep behaviour disorder and spontaneous parkinsonism point towards Lewy-body disease rather than classic FTD.
Hours-to-days change, impaired attention, altered consciousness, infection, medication toxicity or a new lesion indicates delirium or another emergency rather than uncomplicated neurodegeneration.
Disinhibition, impaired judgement and loss of insight can lead to exploitation, unsafe driving, risky sexual behaviour, offending or catastrophic financial decisions.
Progressive aphasia, hyperorality and later dysphagia impair consent, relationships, eating and aspiration safety as disease advances.
Coexisting motor neurone disease or parkinsonism can add weakness, falls, bulbar dysfunction and respiratory failure to cognitive disability.
Personality change, reduced empathy and repetitive behaviour create exceptional relationship and supervision burdens, often precipitating crisis placement or admission.
Early autobiographical recall may appear good while judgement, empathy and semantic knowledge collapse, so memory-led screens under-detect substantial disease.
Loss of initiation without sadness, guilt or subjective distress can reflect frontal network failure; collateral observation helps distinguish overlapping syndromes.
New sweet preference, rigid eating, food seeking or ingestion of non-food items can be a characteristic biological manifestation rather than deliberate misconduct.
Clinical PPA variants identify affected networks, but underlying protein disease varies; logopenic presentations are often Alzheimer-related rather than frontotemporal.
A result may clarify one diagnosis while altering risk for siblings and children, making pre-test counselling and consent boundaries indispensable.
Diagnosing a primary personality or relationship problem from disinhibition or empathy loss without asking whether it is progressive and neurologically patterned.
Excluding FTD because a brief memory screen is acceptable while language, executive function and real-world judgement have deteriorated markedly.
Offering donepezil, rivastigmine, galantamine or memantine as if all dementias share Alzheimer neurochemistry, contrary to NICE guidance.
Using antipsychotic or sedative treatment before analysing triggers, environment, pain, communication and lawful least-restrictive safeguards.
Ordering predictive genetic tests for an unaffected relative without specialist counselling, informed consent and an affected-person testing strategy.
Failing to ask about motor neurone signs, swallowing and respiratory symptoms despite the clinically important FTD-MND overlap.
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A 58-year-old develops progressive tactlessness, loss of empathy, repetitive routines and a new preference for sweet foods. Episodic memory is relatively preserved. Which diagnosis best fits?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
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Management is anticipatory and multidisciplinary. Speech and language therapy supports communication aids and swallowing; occupational therapy simplifies routines and risk; dietetic review addresses hyperorality, weight and dysphagia. Discuss driving, work, finances, internet access, lasting power of attorney and advance care while capacity remains for each decision. FTD can overlap with motor neurone disease, corticobasal syndrome or progressive supranuclear palsy, so review weakness, fasciculation, falls, eye movement and swallowing. Genetic assessment is especially relevant with young onset, multiple affected relatives, motor neurone disease or psychiatric-neurological clustering; C9orf72, MAPT and GRN are important causes, but testing has implications for unaffected relatives. Medication is symptomatic and secondary to environmental formulation. Cholinesterase inhibitors and memantine should not be offered for FTD under NICE guidance.
Review hyponatraemia, bleeding, falls, activation and interactions; avoid using sedation as convenience, document uncertainty and stop when target behaviour does not improve.
Sedation, postural hypotension, falls, priapism and serotonergic interactions matter; an individual target and short review interval are essential.