Reconstructing Ability Before an Accident

How do you know what someone’s thinking skills were before an accident or illness?

This is one of the most challenging questions in neuropsychology. We call it estimating premorbid function. It’s as much an art as a science.

A good neuropsychologist draws on multiple sources:

Life history: education, occupation, and achievements which are interpreted in context. Importantly, we look for a person’s best achievement. Not everyone shines in Year 12, but they may excel later at university or in their career.

Informants: family, friends, or colleagues who knew the person well.

“Hold” tests: abilities resistant to brain injury, like word reading. But this isn’t perfect — for someone with more hands-on intelligence, a spatial test (like block design) may be a fairer indicator.

Statistical models: tools such as the Advanced Clinical Solutions (ACS) compare current performance with an estimated baseline.

⚖️ Even with these methods, there’s no single “gold standard.” For example, Shura et al. (2022) found that word-reading tests can mis-estimate premorbid IQ by a full standard deviation or more. Similarly, Bright and van der Linde (2018) compared different estimation methods and highlighted the strengths and pitfalls of each.

That’s why estimating premorbid function requires weaving together all available evidence, guided by clinical judgment.

Without it, we risk underestimating or overstating the true impact of an injury.

It’s detective work. It’s reconstruction. And it’s the foundation of every fair and accurate neuropsychological assessment.

Bright, P., & van der Linde, I. (2018). Comparison of methods for estimating premorbid intelligence. Neuropsychological Rehabilitation, 28(5), 711–727.

Shura, R. D., Ord, A. S., Martindale, S. L., Miskey, H. M., & Taber, K. H. (2022). Test of premorbid functioning: You’re doing it wrong, but does it matter? Archives of Clinical Neuropsychology, 37(5), 1035–1044.