Today, the famous large language model (LLM) is just one of several leading programs that appear convincingly human in their responses to basic queries.

That uncanny resemblance may extend further than intended, with researchers from Israel now finding LLMs suffer a form of cognitive impairment similar to decline in humans, one that is more severe among earlier models.

The team applied a battery of cognitive assessments to publicly available 'chatbots': versions 4 and 4o of ChatGPT, two versions of Alphabet's Gemini, and version 3.5 of Anthropic's Claude.

Were the LLMs truly intelligent, the results would be concerning.

In their published paper, neurologists Roy Dayan and Benjamin Uliel from Hadassah Medical Center and Gal Koplewitz, a data scientist at Tel Aviv University, describe a level of "cognitive decline that seems comparable to neurodegenerative processes in the human brain."

For all of their personality, LLMs have more in common with the predictive text on your phone than the principles that generate knowledge using the squishy grey matter inside our heads.

What this statistical approach to text and image generation gains in speed and personability, it loses in gullibility, building code according to algorithms that struggle to sort meaningful snippets of text from fiction and nonsense.

To be fair, human brains aren't faultless when it comes to taking the occasional mental shortcut. Yet with rising expectations of AI delivering trustworthy words of wisdom – even medical and legal advice – comes assumptions that each new generation of LLMs will find better ways to 'think' about what it's actually saying.

To see how far we have to go, Dayan, Uliel, and Koplewitz applied a series of tests that include the Montreal Cognitive Assessment (MoCA), a tool neurologists commonly use to measure mental abilities such as memory, spatial skills, and executive function.