CANTABmobile is based on technology that has been used in scientific research for 25 years. Invented at the University of Cambridge, the Paired Associates Learning (PAL) test was developed as a way of assessing episodic memory without language barriers. PAL has been used worldwide in top universities and clinics, and by scientists developing new medicines for Alzheimer's and other diseases. Research using the PAL test has led to 175 publications in peer-reviewed scientific and medical journals.
CANTABmobile uses the knowledge gained from this heritage of research to enable accurate memory assessment in primary care. Some examples of this include the following:
Sensitive to Alzheimer's disease and mild cognitive impairment
Problems with episodic memory can be the first warning signs of Alzheimer's disease and among patients with mild cognitive impairment, tests of episodic memory are the best predictors of subsequent conversion to AD. Across a number of studies, the PAL test shows a sensitivity of 100% and a specificity of 92% in differentiating mild AD from healthy older adults. See How sensitive and specific is the test? in the FAQ section of this site.
Differentiating MCI is more difficult, since not all the MCI group actually have Alzheimer's or another underlying cognitive disease. Nonetheless, the OPTIMA study has reported that PAL scores have a sensitivity of 0.83 and a specificity of 0.82 in differentiating adults with MCI from healthy older adults (Chandler et al., 2008).
Highly sensitive to the cognitive decline seen in amnestic mild cognitive impairment
In a recent study at the University of Tasmania, patients with amnestic MCI showed poorer performance on the PAL than either controls or non-amnestic MCI patients at baseline. When reassessed 10 months later, patients with amnestic MCI had worsened by an average of 4 errors at the 6-pattern stage. In contrast, the PAL scores of patients with non-amnestic MCI, who are at lower risk for Alzheimer's disease, changed by less than one error. (Saunders & Summers, 2011).
Performance depends on the brain regions that are affected first in Alzheimer's disease
The PAL test depends on the integrity of the hippoccampal formation, the braIn structure which is affected first in Alzheimer's disease. Neuroimaging studies of healthy older adults completing the PAL test have shown that bilateral hippocampal activation increases as the number of patterns that the patient must remember goes up (de Rover et al, 2011).
Helps differentiate depression from MCI and dementia
The PAL test is highly sensitive to the early signs of dementia but is generally unaffected by the symptoms of depression. Blackwell et al (2004) showed that individuals with major unipolar depression show PAL scores similar to age-matched healthy controls, with little overlap between these groups and patients with mild Alzheimer’s disease. In addition, CANTABmobile includes a standardised assessment of depression, the Geriatric Depression Scale (Yesavage et al, 1983). This well-validated scale allows self-reported mood symptoms to be assessed in multiple languages.
Based on a large UK normative database
CANTABmobile is based on a dataset of more than 4000 older adults collected through a number of different UK research projects. This large dataset allows a very accurate assessment of the expected level of memory performance for any individual aged 50 to 90 years.
A patient’s score is automatically adjusted to take into account the effects of age, education and gender on memory. Women make slightly fewer errors on the PAL test than men, and people who have spent longer in education tend to have slightly better scores. These effects are relatively small compared to the effect of ageing, shown below. Episodic memory tends to develop in early childhood and remains relatively stable through mid-life, before worsening in later life.
Performance on the PAL test across the lifespan