Lawrence C. Perlmuter

Decreased cognitive function in aging non-insulin-dependent diabetic patients

A cross-sectional study was conducted to determine whether normal, age-related declines in cognitive function are accelerated in non-insulin-dependent (type II) diabetes mellitus. Study participants ranged in age from 55 to 74 years. Results indicate that cognitive function is inferior in the patients with type II diabetes compared with a comparably aged, nondiabetic control group. On the basis of a series of cognitive tests, it appears that the cognitive impairment is due to a deficiency in memory retrieval rather than to an attentional or encoding deficit. Cognitive performance is poorer in diabetic patients with peripheral neuropathy or elevated hemoglobin A1c levels. The apparent cognitive impairment in aging patients with type II diabetes may complicate adherence to medical regimens.

Retinopathy in Older Type II Diabetics Association With Glucose Control

Non-insulin-dependent (type II) diabetics over the age of 55 comprise most of the diabetic population and are at considerable risk for the development of both macrovascular and microvascular complications. We studied the prevalence of retinopathy and its association with putative risk factors for its development in an elderly (55- to 75-yr-old) population of type II diabetics. Our cross-sectional analysis revealed that duration of diabetes and hemoglobin A1c (HbA1c) concentration were the two major predictors of the presence of retinopathy. Duration effect was seen after 10 yr of diabetes, whereas HbA1c effect was linear over its entire range. Hypertension, which has been reported to be a risk factor for microvascular disease in younger diabetic patients, was not associated with retinopathy in the older type II population. Multiple logistic regression analysis revealed that both the duration of diabetes and HbA1c remained significant independent determinants of retinopathy even after taking age and blood pressure into account. Our results support an etiologie role for metabolic control in the development of retinopathy in the elderly type II population.

Age and diabetes related changes in verbal fluency

Non-insulin-dependent diabetes mellitus is present in 7-10% of the aged. This disease appears to be associated with an acceleration of the aging process and results in compromised performance on learning and memory tasks. The present study used a verbal fluency test to examine semantic memory performance in two age groups (55-64 and 65-74 years) of diabetic subjects and controls. In addition, immediate and secondary memory were also examined using the digit symbol and digit span tests and a serial learning task. Results showed that digit symbol performance was poorer for older subjects and diabetics while serial learning was poorer only for diabetic subjects. However, the number of words generated on the verbal fluency test was similar for all groups. Qualitative analyses of the verbal output revealed that older subjects and diabetics produced the greatest number of previously recited words (repetitions). Repetitions may signal a failure to adequately monitor behavior which in turn could contribute to cognitive decline.

Memory self-assessment and performance in aged diabetics and non-diabetics

Non-insulin dependent diabetes in older adults is associated with elevated depression and a greater decline in certain aspects of cognitive functioning than is found with normal aging. This study sought to determine whether diabetics report more memory complaints in carrying out their daily activities, and if memory self-assessments are reflective of performance on laboratory tasks. Middle-aged (55-64 years) and old (65-74 years) diabetics and non-diabetic control subjects were studied. Results showed that both diabetes and increased age were associated with poorer performance on some cognitive tests as well as with more self-reported memory problems. When depression levels were statistically controlled, the diabetes variable was no longer a significant predictor of memory complaints. The usefulness of self-assessments as an adjunct to more objective cognitive test measures was discussed.

Triglyceride levels affect cognitive function in noninsulin-dependent diabetics

Noninsulin-dependent diabetes mellitus (NIDDM) is associated with decrements in several cognitive functions. Among the variables that apparently contribute to the decline in cognitive performance is poor glucose control, as measured by hemoglobin A1c. Elevated levels of triglycerides in diabetics may also contribute to this cognitive decline through the increased incidence of atherosclerosis in these patients. The authors examined the relationship between triglycerides and cognitive performance in 246 NIDDM outpatients, aged 55-74 years. The relationship between triglyceride levels and performance on three cognitive tasks and on a test of reaction time was measured. Elevated levels of triglycerides were associated with significant decrements in performance on the digit symbol substitution test, digit span (backward) test, and on a reaction time measure. High levels of triglycerides, independent of chronic glucose control, appear to contribute to the decreased ability to perform short-term memory tasks in NIDDM.

Depression and Diabetic Neuropathy: A Complex Relationship

In a group of 64 non-insulin-dependent diabetic females, a significant positive correlation between Zung self-rated depression scores and objective measurements of diabetic peripheral neuropathy was limited to those women with Zung scores greater than 50 (depressed group, n = 12). In the overall group, there was no significant linear or quadratic relationship between peripheral neuropathy and depression scores. The associations between depression, peripheral neuropathy, and diabetes are discussed. ( J Geriatr Psychiatry Neurol 1988;1:11-15).

Perceived Control A Generalized State of Motivation

Permitting subjects to choose materials to be learned on a task enhances performance on that task. These results support the idea that choice increases the learners perception of control, thereby enhancing motivation and performance. The purpose of the present experiments was to determine whether choosing responses to be learned on a paired-associate task would also benefit performance on a reaction-time task. Half of the subjects selected their responses to be learned on a paired-associate task while the remaining subjects were assigned responses. In one experiment, subjects then performed both the PA and RT tasks simultaneously, while in the second experiment the RT task was performed following the choice/force procedure. Providing the learner with the opportunity to choose produced a generalized increase in motivation, which resulted in significantly faster responding on the nonchosen RT task. Also discussed are the limitations of the effects of perceived control.

Performance as a source of perceived control

The purpose of this experiment was to examine the effects of choice and environmental control on the development of the perception of control. The results showed that the perception of control develops from an opportunity to make choices. More deliberate (slower) decisions resulted in an increase in the perception of control, and these perceptual effects generalized to a dice-throwing task over which no choice was possible. A model was examined which assumes that subjects monitor their own behavior with the result that more thoughtful decisions lead subjects to infer higher levels of control.

Cognitive Function in Non-Insulin-Dependent Diabetes

Patients with non-insulin-dependent diabetes mellitus (NIDDM) are likely to show selective cognitive decrements relative to age-matched controls—a relationship that has been shown in some but not all studies (cf., Mattlar, Falck, Ronnemaa & Hyyppa, 1985; Perlmuter et al., 1984). While such decrements in cognitive performance might be the result of any of several disease-related alterations in biologic function, a primary etiology may be impaired glucose control (Reaven & Thompson, 1988). The influence of glucose levels and regulation on learning and memory has been demonstrated in humans (Perlmuter, Tun, Sizer, McGlinchey & Nathan, 1987) and animals, diabetic and non-diabetic (Gold & Stone, 1988).

Visual Recognition Memory for Binary Pictures: Another Look.

Recognition memory for matrices of 0s and 1s was examined as a function of the number of elements (complexity) and density of those elements within the matrix. It was found that with greater density and lesser complexity, recognition performance improved. This result contradicts an earlier finding of Green and Purohit, who concluded that the more complicated matrices led to better performance. The present study suggests that their conclusion was erroneous and stemmed from failure to control the physical parameters of density and number of elements in the matrix. Implications for the general problem of recognition memory and eye movements are discussed.