Cognitive Impairment in Diabetes

Type 2 diabetes (T2DM) is associated with an increased risk of cognitive
impairment, including dementia. Cognitive impairment is often undiagnosed. This
is an important problem since cognitive impairment in T2DM is known to be
associated with impaired self management and an increased incidence of
diabetes-related complications. These problems may be reduced by improving care
and social support in people with established cognitive impairment. Unlike
other diabetic complications, cognitive impairment is not yet routinely
evaluated in daily practice. The establishment of a reliable and efficient test
is an essential first step in the early detection and management of cognitive
impairment in T2DM

Overall aim
The ultimate goal of our studies is to optimize treatment and reduce treatment
related complications in patients with diabetes and cognitive impairment

Our specific objectives are to:
1. assess the validity of two self-administered cognitive test instruments to
detect cognitive impairment in older patients with T2DM in a primary care
setting and select the optimal instrument
2. assess the diagnostic accuracy of a standardised GP evaluation in detecting
unrecognised cognitive impairment in patients with T2DM
3. estimate the accuracy and efficiency of the combination of the optimal
instrument with the GP evaluation

Secondary objective:
4. provide a detailed characterisation (cognitive profile, brain MRI,
diagnosis) of a population based sample of patients with T2DM and cognitive
impairment
5. to examine the effect of the diagnostic procedure on diabetes care and
patients* quality of life six and twenty-four months after a diagnosis of
cognitive impairment

The Cognitive Impairment in Diabetes study (COG-ID) will include 228 people
aged >=70 with T2DM. These people will be recruited from participating general
practices and are diagnosed with T2DM but not known with cognitive impairment.
All participants will undergo an evaluation including two self-administered
instruments (*Test Your Memory* and *Self-Administered Gerocognitive
Examination*) and a standardised assessment for cognitive impairment by a
general practitioner (GP), including a Mini Mental State Examination (MMSE). In
addition, a quality of life and depressive symptom questionnaire (SF-36 and
CES-D) will be filled out. All participants suspected of cognitive impairment
(on either cognitive test instrument or the GP assessment) and a random sample
of 30% of participants without suspicion of cognitive impairment will be
referred to the memory clinic in the UMCU, where a medical examination,
neuropsychological examination and MRI will be performed. At the memory clinic
the main outcome (i.e. presence or absence of cognitive impairment) will be
determined, defined as a clinical diagnosis of either mild cognitive impairment
(MCI) or dementia. These diagnoses will serve as reference standard. Based on
the reference standard the outcome of the cognitive test instruments will be
classified as true or false positive and true or false negative and the
diagnostic accuracy of the cognitive test instruments, separate and combined,
will be examined.
The results will be communicated to the GP and patients according to a
predefined protocol. In case of a diagnosis of cognitive impairment the GP is
suggested to adjust the diabetes regimen. After six and twenty-four months a
follow-up questionnaire will be sent to the patient to assess the impact of the
study on the quality of life and depressive symptomatology of patients.

There are no health risks associated with the procedures and techniques used.
A diagnosis of MCI or, even more so, dementia can have substantial impact on
patients and their relatives. Nevertheless, it is important to emphasize that
these diagnoses can only be established if the patient and/or the relatives
themselves express serious cognitive complaints. Hence, although the patient
or relatives might be in denial, the diagnosis will generally not come as a
surprise. Often the diagnosis will help to understand the cause of complaints
and insecurities that have already bothered people for a long time.
The diagnosis of dementia or MCI will be established according to
internationally accepted criteria, at a specialist clinic. In this setting the
risk of false positive dementia diagnosis is minimal. In case of doubt, no
diagnosis will be established, and the patient will be offered a reevaluation
after 6 to 12 months.
The results of the study will contribute to an earlier detection of cognitive
impairment in patients with T2DM and thus help to improve treatment for these
patients in the future. Direct implementation of this diagnostic procedure in
all general practices in the Netherlands or abroad seems feasible.