Evaluation of Cognitive Functions of Individuals Older Than 65 With Diagnosis of Diabetes

Introduction

In the developed countries, the population in the geriatric age-group constitutes a significant part of the population. This ratio is expected to increase further in the coming years. ¹ According to data of Turkey Statistical Institute, the elderly population in our country (65 and above) was 6 651 503 in 2016. ² With the development of technology, the expected increase in the length of life causes an increase in chronic illness. Diabetes is one of the first 5 diseases among the common chronic diseases in the society. ² According to Turkey’s health survey data, the rate of incidence of diabetes in Turkey was found to be 6.7%. ² The known number of diabetic patients in the 65 to 99 age-group in the world is 122.8 million; the rate of incidence of diabetes in the older age-group is increasing steadily. ¹ Diabetes is a systemic disease that can damage every organ in the body, including retina, skin, kidney, small and large vessels, and central and peripheral nerves, and it has an increasing frequency with obesity and advancing age. The duration of life with this disease is prolonged as the approaches to classical micro- and macrovascular disease prevention and treatment are improved. This means that existing treatment strategies for type 2 diabetes may lead to new nonaimed complications. Cognitive inefficiency and dementia are examples of these new complications. The correlation between diabetes and cognition has drawn more attention in the last decade. Cognition includes a group of mental functions such as attention, memory, learning, verbal recall, concentration, reasoning, problem-solving, and decision-making. ^{3 –5} The pathophysiology of the cognitive dysfunction of diabetes is not fully understood, but hyperglycemia, vascular disease, hypoglycaemia, and insulin resistance play an important role. ⁶ Diabetes is known to cause structural damage and functional disorders in various tissues and organs with time. Diabetes has been reported to cause a variety of cerebrovascular, neurochemical, and electrophysiological changes in the central nervous system. Due to these changes, the cognitive functions also become distorted. Experimental studies have reported that depression and anxiety levels increase as the age of experimental diabetic animals increases. Problems occur in the cognitive functions such as problem-solving, attention, interpretation in these study. ^5,7 However, the age of onset of diabetes, the glycemic control level, and the duration of diabetes affect the severity of cognitive deficiency. A mild cognitive inefficiency, a disorder that involves a decrease in cognition, does not usually significantly interfere with daily independent function, but is a risk factor for dementia. ^6,8 There are clinical trials that report an attenuation of the cognitive functions, a decrease in abstract reasoning and the complex psychomotor activity, and an increased risk of dementia in patients with type 2 diabetes mellitus (DM). ^7,9 The evaluation of a patient in the geriatric age-group is a time-consuming operation. Therefore, there is a need for, as short as possible, standard and sensitive assessment tools that also can be implemented by health personnel for the diagnosis of certain diseases or symptoms, except for general health checks, internal, neurological, or psychiatric evaluations. The evaluation of the cognitive status and taking necessary precautions for diabetic patients are important for managing the procedure and preventing complications. ^3,10 The goal of evaluating cognitive functions in a diabetic patient is to maintain the treatment and to know whether he needs help to manage diabetes. Thus, health professionals, patients, and caregivers will be able to predict the cognitive dysfunctions of elderly individuals with diabetes and take necessary precautions. ^5,11,12 This hypothetical study was conducted to evaluate the cognitive functions of patients diagnosed with diabetes above 65 years of age.

Materials and Methods

Results

The average age of the patients was 70.56 ± 3.81 years (min: 65, max: 81), 60.4% were male, 89.9% were married, 54.9% were primary school graduates, and 97.8% had social security. It was found that 82.4% of the patients did not have an accident history, 64.8% did not undergo any surgery before, 68.1% had another chronic disease other than diabetes, 75.8% did not smoke cigarettes, and all of them were using drugs continuously. It was found that the average use of medication was 3.33 ± .77 (min: 1, max: 5). The average MoCA Scale score of the patients was found to be 19.61 ± 1.70 (min: 15, max: 26; Table 1).

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Table 1.

Demographic Characteristics of the Patients.^a

	n		%
Gender
Female	36		39.6
Male	55		60.4
Marital status
Married	81		89.0
Single	10		11.0
Educational level
Primary school	64		70.3
Secondary school	18		19.8
High school	6		6.6
University	3		3.3
Social insurance
Have	89		97.8
Have not	2		2.2
Accident history
Have	16		17.6
Have not	75		82.4
Surgery history
Have	32		35.2
Have not	59		64.8
Chronic disease
Have	62		68.1
Have not	29		31.9
Smoking
Have	22		24.2
Have not	69		75.8
Continuous drug use status
Yes	91		100
No	0		0
	Min	Max	Mean (SD)
Age	65	81	70.56 ± 3.81
Number of drugs used	1	5	3.33 ± .77
MoCA total	15	26	19.61 ± 1.70

Abbreviations: MoCA, Montreal Cognitive Assessment; min, minimum; max, maximum; X, mean.

^a N = 91.

There was no significant relationship between the age of the patients and the cognitive assessment scale when the individual characteristics of the patients were compared with the Montreal Cognitive Rating Scale Score and there was a negative weak significant correlation with the number of used medications (r = −0.206; P = .051). A statistically significant difference was found between the gender of the patients, educational status, having another chronic disease, and the MoCA Scale averages (P < .05). There was no statistically significant difference between the marital status, social security, the accident and operative history, the smoking status of the patients, and the MoCA Scale total average scores (P > .05; Table 2).

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Table 2.

Comparison of the Montreal Cognitive Assessment Scale Point Averages According to Individual Characteristics and Clinical Characteristics of Patients.

	MoCA
Age	r = −.108 P = .307
Number of drugs used	r = −.206 P = .051
(n)	Mean (SD)
Gender
Female (36)	19.08 ± 1.85
Male (55)	19.96 ± 1.51
t	−2.477
P	.015 a
Marital status
Married (81)	19.67 ± 1.61
Single (10)	19.10 ± 2.33
U	361 000
P	.568
Educational level
Primary school (64)	19.53 ± 1.42
Secondary school (18)	18.94 ± 1.47
High school (6)	21.66 ± 2.87
University (3)	21.33 ± 2.51
F	5.652
P	.001a
Social insurance
Have (89)	19.64 ± 1.71
Have not (2)	18.50 ± .70
U	44 000
P	.258
Accident history
Have (16)	20.18 ± 2.19
Have not (75)	19.49 ± 1.57
U	520 000
P	.394
Surgery history
Have (32)	19.18 ± 1.57
Have not (59)	19.84 ± 1.74
t	−1.839
P	.070
Chronic disease
Have (62)	19.32 ± 1.88
Have not (29)	20.24 ± .98
U	508 000
P	.001a
Smoking
Yes (22)	19.72 ± 2.00
No (69)	19.57 ± 1.61
U	735 000
P	.820

Abbreviations: MoCA, Montreal Cognitive Assessment; X, mean.

^a P < .05

Discussion

Diabetes is an important risk factor for cognitive dysfunction and dementia. ^5,6,8,16 In patients with type 2 DM, a cognitive function decrease, a decrease in abstract reasoning and complex psychomotor activity, and an increase in the dementia risk increases show up. ^5,10 When compared to people without diabetes, diabetics suffer from cognitive dysfunction, particularly in memory and managerial functions. ⁷ The total MoCA cutoff score for cognitive inefficiency diagnosis is accepted as 21 points. According to our results, the cognitive functions of the participants were low (average 19). In case–control studies, type II DM cases have been shown to be worse in terms of verbal memory, speed of information processing, attention, and managerial activities compared to age, gender, and education-matched control group. ⁷ Diabetes is a disease that can cause cognitive dysfunction independent of other factors. Cognitive functions are reported in the studies to be impaired with advancing age. ^5,12,18 There was no significant relationship between age and cognitive function in our study. The age range of the participating participants was 65 to 80. When the literature is reviewed, it is reported that the incidence of cognitive dysfunction, dementia, and Alzheimer is increased at people above 80 years of age. After the age of 85, the probability of getting a diagnostic of the Alzheimer’s disease is more than one-third. ¹⁵ It is thought that there are no significant associations between the samples constituting our study, while there are no individuals over 80 years old and the age groups are close.

When cognitive functions of participants were evaluated according to gender, they were found to be below the average of both genders; it is seen that the cognitive evaluation score of women is slightly lower than that of men. Elderly women living in society all over the world are at an economic, cultural, and political level of disadvantage compared to older men and it is stated that this will also negatively affect the health-related parameters of older women. ¹¹ Age, gender, and educational status are shown as risk factors for cognitive inefficiency in patients with diabetes. Another study showed that the general health status of older women was significantly more affected by depressive symptoms than by male elderly people. In the same study, it was stated that the cognitive functions of both genders were similar. ¹⁹ Again, in a study conducted in our country, it is stated that elderly women are a risk group in terms of depression and cognitive inefficiency. ¹² Our research result is compatible with the literature.

According to our study, when we look at the general average, the cognitive function scores of high school and college graduate participants are above the average. Education is an important factor in assessing cognitive function. Another scale used for cognitive evaluation is the minimal test. While in this test a score of 26 and below was sufficient for dementia for those who had an education for 8 years and above, this score is 18 or less for person who had an education for 1 to 8 years. ⁷ Studies show that the more the education level increases, the more cognitive impairment decreases. In a study conducted in Trabzon, the lack of education was reported as a risk factor for cognitive dysfunction. ¹² In the study in which the reliability of the Turkish Cognitive Assessment (MOCA) Scale was made, it was stated that education was a factor affecting the test result. ¹⁴ Our research result supports the literature knowledge. The cognitive evaluation average scores of participants with a chronic illness were lower than those without an illness. Due to the advanced age of the sample group, it is not possible to eliminate all chronic diseases. For this reason, neurological disorders such as Parkinson, dementia, Alzheimer, psychiatric disorders, and neurosurgery, which may directly affect the cognitive level, have been determined as exclusion criteria. When the literature is reviewed, hypertension and heart diseases in diabetic patients can also affect cognitive functions. ¹⁸ The fact that cardiac disease are no exclusion criterion was accepted as a limitation in our study.

Conclusion and Recommendations

Diabetes is a risk factor for cognitive dysfunction in individuals over 65 years of age. Cardiovascular diseases are considered as exclusion criteria and new studies, regular monitoring of the cognitive functions of diabetic patients, and the use of the MoCA Scale are recommended.