When Symptoms Are Overlooked: Diagnostic Overshadowing and Health Inequalities in People with Learning Disabilities

When an existing diagnosis becomes the explanation for every new symptom, treatable illness can disappear from view. Understanding diagnostic overshadowing means examining clinical reasoning, communication and the organisation of care, while keeping the person's experience at the centre.

Imagine an adult with a learning disability who begins refusing meals and pushing people away during support with washing. A note describes “increasingly challenging behaviour”. At an appointment, discussion focuses on managing agitation; nobody establishes whether eating, movement or touch has become painful. Dental disease, an injury, depression or a frightening experience might each deserve consideration.

This is a hypothetical example, not a patient case. It illustrates how a description of behaviour can become an explanation before an assessment has established what changed. Our earlier article on psychologically informed crisis care considered responding to distress. Here, the focus is the diagnostic process: how physical and mental health needs can be missed, and what helps keep assessment open.

What is diagnostic overshadowing?

Diagnostic overshadowing occurs when symptoms of another condition are incorrectly attributed to an existing diagnosis. In learning disability services, this may mean interpreting low mood as an inevitable feature of disability or treating a new expression of pain as an established behavioural difficulty (Dell'Armo & Tassé, 2024; Ali et al., 2013).

“Learning disability” is used here in its UK sense; international research usually uses “intellectual disability”. It involves lifelong differences in intellectual and adaptive functioning. Communication and support needs vary widely (General Medical Council [GMC], n.d.). Autism is distinct and may coexist with a learning disability. An autism diagnosis should likewise prompt appropriate adjustments without becoming a blanket explanation for new symptoms.

Overshadowing is more specific than diagnostic uncertainty or an eventual misdiagnosis. The concern is that an existing label wrongly narrows interpretation. Not every missed condition establishes that this bias occurred, and recognising a person's disability remains important for providing accessible care.

What does the evidence show—and leave uncertain?

Dell'Armo and Tassé's (2024) systematic review included 25 studies of overshadowing of psychological disorders in people with intellectual disability. Around one third did not find overshadowing. Overall evidence quality was rated low, with outdated studies, hypothetical case methods, small convenience samples and analytical weaknesses. These findings support vigilance but do not establish a reliable contemporary prevalence, particularly for physical healthcare or Northern Ireland.

Other research reveals relevant barriers without measuring the same phenomenon. Interviews with people with mild or moderate intellectual disabilities and carers described communication problems, unfair treatment and failures to adjust services, alongside examples of good care (Ali et al., 2013). Such accounts illuminate experiences and possible mechanisms; small qualitative samples cannot estimate how often they occur across healthcare.

In six English acute hospital trusts, a mixed-methods study found that reasonable adjustments were inconsistently implemented, with unclear responsibilities and weak systems for identifying needs (Tuffrey-Wijne et al., 2014). England's Confidential Inquiry also identified care and service factors contributing to premature deaths (Heslop et al., 2014). These studies demonstrate serious concerns; they do not show that overshadowing explains every inequality or supply current Northern Ireland mortality estimates.

The evidence also leaves gaps concerning people with profound disabilities, limited speech and intersecting disadvantages. Studies of diagnostic judgements, lived experiences and mortality answer different questions and should not be treated as interchangeable measures. Better research needs to establish which changes improve assessment in everyday services, rather than assume that awareness training alone prevents error.

Physical health, mental health and communication interact

Comprehensive assessment in a Scottish cohort documented substantial physical multimorbidity, including sensory impairments, epilepsy and constipation (Kinnear et al., 2018). Multiple conditions can complicate interpretation. A change in activity could involve pain, medication effects, low mood, disrupted sleep or several influences together. A disability diagnosis does not settle that differential assessment.

Mental health needs can also disappear behind physical or developmental explanations. A meta-analysis estimated co-occurring psychiatric disorders in about one third of adolescents and adults with intellectual disability, but with considerable heterogeneity between studies (Mazza et al., 2020). That pooled estimate describes varied populations and methods, rather than an individual's likelihood of a particular disorder.

NICE (2016) advises clinicians to consider physical illness when assessing apparent mental health changes, while recognising that physical, sensory or cognitive conditions may mask mental health problems. Withdrawal, irritability or loss of interest warrant enquiry, rather than automatic classification as depression. Conversely, investigating pain should not prevent attention to grief, anxiety, trauma or other distress.

Recognising pain when speech is limited

A systematic review identified facial expressions, movements, non-verbal vocalisations and social-emotional changes among potential behavioural indicators of pain. It also found that identifying a pattern specific to pain remained difficult (de Knegt et al., 2013). A grimace, silence or repeated movement may be informative, but no single behaviour reliably establishes its cause.

Assessment therefore needs the person's own account wherever possible, adapted to their communication, alongside observation and clinical examination. Comparing current expression with familiar patterns can help. A supporter might report that someone usually enjoys meals but now turns away when chewing; that observation raises an assessment question rather than proving dental pain.

Communication barriers also arise in the consultation itself. A review of autistic adults' access to physical healthcare identified communication, sensory and planning barriers (Mason et al., 2019). These findings should not be assumed to describe everyone with a learning disability, but they underline the importance of asking which adjustments this individual needs.

How assumptions can close an assessment

One plausible route to overshadowing is anchoring: an existing diagnosis becomes the starting point around which later information is organised. A description such as “attention-seeking” can then influence what questions are asked and which observations seem credible. This is an explanatory possibility, not proof of a particular clinician's motives or a mechanism established in every case.

The evidence on inconsistent adjustments also cautions against locating the whole problem inside individual attitudes (Tuffrey-Wijne et al., 2014). An inaccessible appointment or an unclear handover can limit the information available for good decisions. Diagnostic curiosity needs practical conditions: time to communicate, access to relevant history and responsibility for following up unanswered questions.

Comprehensive assessment and psychological formulation

A useful starting question is: “What is different for this person, and over what period?” Assessment can bring together the timing of symptoms, physical and psychiatric history, medicines, sleep, eating, daily functioning and recent environmental changes. NICE (2015) recommends considering physical and mental health, communication and environmental factors when assessing behaviour that challenges.

The task is to compare explanations and identify the appropriate investigations or specialist input. Behavioural observation may reveal a relationship with meals, movement or particular interactions. It cannot by itself exclude illness. A psychological explanation should remain revisable when symptoms change or expected improvement does not occur.

Formulation connects evidence about the person with hypotheses about how difficulties develop and persist. The British Psychological Society (2025) describes this as collaborative, ongoing sense-making, open to revision. In the hypothetical example, painful eating and anxiety about support might interact. That formulation would need checking with the person and relevant professionals; it would not replace medical assessment. Our article on psychological formulation beyond diagnosis explores this distinction.

Documentation can make this process clearer. “Turned away from lunch on three occasions” records an observation; “refused because of disability” adds an untested explanation. Recording what was observed, what the person communicated, which explanations remain possible and when reassessment is due helps the next professional continue the enquiry. An unresolved concern needs an identified owner, rather than simply another referral.

What multidisciplinary working adds

Different professionals contribute different expertise. Medical practitioners investigate and treat physical illness; psychiatrists contribute specialist psychiatric assessment; nurses monitor health and coordinate care. Speech and language therapists can support communication, and occupational therapists can examine participation, daily activities and environmental demands. The mix depends on assessed needs.

Clinical psychologists contribute psychological assessment and formulation, adapted interventions, consultation and support for teams' understanding of distress. In consultation, they can help distinguish observation from interpretation, consider alternative explanations and agree how hypotheses will be reviewed. NICE (2016) supports coordinated assessment and formulation-based care planning; this is shared work, rather than a responsibility belonging solely to psychology.

Families, advocates and support workers may recognise subtle changes that unfamiliar professionals miss. Their knowledge should inform assessment with appropriate consent and confidentiality, while the person remains directly involved (GMC, n.d.). Disagreement deserves exploration. Fluency, professional status or familiarity should not automatically determine whose account is accepted.

The Northern Ireland context

Northern Ireland's Health and Social Care (HSC) services provide a setting for this coordination. Belfast Trust describes community learning disability treatment services involving clinical psychology, psychiatry and community learning disability nursing (Belfast Health and Social Care Trust, n.d.). This illustrates local provision; eligibility, pathways and availability need checking with the relevant service.

Guidance needs jurisdictional care. Northern Ireland's Department of Health records endorsement of NICE NG11 in July 2015 and NG54 in November 2016 (Department of Health [NI], 2015, 2016). These guidelines must be read with NI-specific law and policy. GMC professional standards apply across the UK. The English hospital research discussed above offers comparative evidence, rather than a description of HSC performance. NI Direct also explains that Northern Ireland healthcare providers must make reasonable adjustments (NI Direct, n.d.).

The regional HSC Hospital Passport records communication preferences, health history and support needs (Public Health Agency, 2019). It can make important information available, provided staff read it and check that it is current. A completed passport does not replace conversation or assessment.

The Department's “We Matter” consultation sought a more consistent adult learning disability service model, including health, meaningful lives and responses to distress. Its consultation page reports analysis and further work towards finalisation (Department of Health [NI], 2025). Proposed reform is not evidence of completed implementation or reduced diagnostic error. Broader questions of access and exclusion also connect with our article on social conditions and mental health.

Reducing risk while protecting autonomy

Make communication usable

Plain language, visual information, additional processing time, quieter appointments and a trusted supporter may help, depending on the person's preferences. Check understanding without relying solely on agreement. GMC consent guidance emphasises information, time and support for decision-making (GMC, 2020, updated 2026). Limited speech should not be treated as evidence of incapacity. Capacity concerns the particular decision at the relevant time, with appropriate support offered to help the person understand and communicate their choice.

Follow through on health needs

A systematic review found that health checks consistently identified previously unrecognised needs and prompted action (Robertson et al., 2014). Detection still requires follow-up. A practical plan should identify who will arrange investigations, communicate results and review persistent symptoms; a scheduled check cannot replace timely assessment of a new concern.

Keep dignity and safeguarding together

Support participation and privacy, and assess concerns about abuse or neglect through appropriate safeguarding procedures without presuming a cause. Consent and capacity decisions must follow the applicable law. Northern Ireland's Mental Capacity Act 2016 remains partially commenced; England and Wales's framework should not simply be imported (Department of Health [NI], n.d.). Safeguarding should enable the person to be heard, rather than automatically displace their choices.

Keep the diagnostic question open

Reducing diagnostic overshadowing means preserving the possibility that a new symptom deserves a new explanation. It requires accessible encounters, careful comparison with the person's usual experience, medical and psychological assessment, and a team willing to revise its account. The evidence does not justify a single prevalence figure or a universal intervention. It does justify taking changes seriously and asking what remains unexplained. Person-centred care protects both the person's authority over their life and their opportunity to receive appropriate healthcare.

Author: Arkadiusz Dawidowicz

This article provides general educational information and is not a substitute for individual clinical assessment or care. New or worsening symptoms require assessment through the appropriate healthcare service. Northern Ireland policy and guidance sources were checked on 25 October 2026.

References

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