Assessing mental capacity is a delicate and highly structured process that requires clear communication, accurate understanding, and thoughtful interpretation. When a neuropsychologist carries out a mental capacity assessment, they must ensure that the individual fully comprehends the information presented, is able to retain and weigh it, and can communicate a decision effectively. But what happens when language or communication difficulties interfere with that process? This is where Speech and Language Therapists (SLTs) become essential collaborators — and why their involvement can make or break the validity of the assessment.
Communication as the Foundation of Capacity
Under the Mental Capacity Act (2005), a person’s ability to make decisions is judged on four core criteria: understanding, retaining, weighing, and communicating information. The last of these — communication — is often the most easily underestimated. If a person cannot express themselves clearly or understand complex verbal information, they may appear to lack capacity when, in fact, their reasoning is intact but masked by communication barriers.
Neuropsychologists are skilled in assessing cognitive functions such as memory, attention, and reasoning. However, when speech, language, or comprehension are affected — for example, following a stroke, traumatic brain injury, or neurodegenerative condition — the expertise of a Speech and Language Therapist becomes vital to ensure that results are fair, valid, and legally defensible.
The SLT’s Role in Ensuring Fair Assessment
An SLT can assess and support communication across multiple domains: expressive and receptive language, verbal reasoning, social communication, and non-verbal understanding. They help identify whether difficulties lie in cognition or communication — a crucial distinction in capacity assessments.
For instance, a person with expressive aphasia may fully understand a financial or medical decision but struggle to articulate their reasoning. Without SLT input, they risk being wrongly deemed to lack capacity. Conversely, an SLT can help adapt the assessment process — simplifying language, using visual aids, or providing supported communication tools — so the neuropsychologist can accurately gauge capacity based on understanding rather than speech fluency.
A Collaborative Approach
When SLTs and neuropsychologists collaborate, they create a more holistic picture of an individual’s decision-making abilities. The neuropsychologist focuses on cognitive reasoning and executive function, while the SLT ensures that communication challenges are not mistaken for cognitive deficits. Together, they uphold the legal and ethical principle that capacity should never be denied simply because a person communicates differently.
This joint approach is particularly valuable in medicolegal and Court of Protection contexts, where assessments must withstand scrutiny. Reports that integrate SLT findings provide stronger, more transparent evidence and are less likely to be challenged in court.
The Consequences of Omission
When SLT involvement is overlooked, the risk of misinterpreting communication barriers as cognitive incapacity increases significantly. Such errors can have serious implications — from denying someone the autonomy to make decisions about their care or finances, to undermining the credibility of the medico-legal process itself.
At Medico-Legal Healthcare, our neuropsychologists can work closely with Speech and Language Therapists to ensure that every mental capacity assessment is accurate, fair, and person-centred. By combining cognitive expertise with specialist communication assessment, we safeguard the integrity of decision-making evaluations and uphold the individual’s right to be heard and understood.