Changes in auditory P300 event-related potentials and brainstem evoked potentials in diabetes mellitus

Evaluation of Event-Related Potentials in Somatic Diseases - Systematic Review

Many somatic illnesses (e.g. hypertension, diabetes, pulmonary and cardiac diseases, hepatitis C, kidney and heart failure, HIV infection, Sjogren's disease) may impact central nervous system functions resulting in emotional, sensory, cognitive or even personality impairments. Event-related potential (ERP) methodology allows for monitoring neurocognitive processes and thus can provide a valuable window into these cognitive processes that are influenced, or brought about, by somatic disorders. The current review aims to present published studies on the relationships between somatic illness and brain function as assessed with ERP methodology, with the goal to discuss where this field of study is right now and suggest future directions.

Diabetes exacerbates brain pathology following a focal blast brain injury: New role of a multimodal drug cerebrolysin and nanomedicine

Blast brain injury (bBI) is a combination of several forces of pressure, rotation, penetration of sharp objects and chemical exposure causing laceration, perforation and tissue losses in the brain. The bBI is quite prevalent in military personnel during combat operations. However, no suitable therapeutic strategies are available so far to minimize bBI pathology. Combat stress induces profound cardiovascular and endocrine dysfunction leading to psychosomatic disorders including diabetes mellitus (DM). This is still unclear whether brain pathology in bBI could exacerbate in DM. In present review influence of DM on pathophysiology of bBI is discussed based on our own investigations. In addition, treatment with cerebrolysin (a multimodal drug comprising neurotrophic factors and active peptide fragments) or H-290/51 (a chain-breaking antioxidant) using nanowired delivery of for superior neuroprotection on brain pathology in bBI in DM is explored. Our observations are the first to show that pathophysiology of bBI is exacerbated in DM and TiO₂-nanowired delivery of cerebrolysin induces profound neuroprotection in bBI in DM, not reported earlier. The clinical significance of our findings with regard to military medicine is discussed.

Study of Neurocognitive Function in Type 2 Diabetes Mellitus Patients Using P300 Event-Related Potential

Background:

Diabetes mellitus is the most prevailing metabolic disease. It causes structural and functional alterations in several organs, including the central nervous system. Altered glucose metabolism, atherosclerosis, and inflammation of blood vessels are seen in diabetes. This may lead to neuronal degeneration and decline in cognition. Event-related potential P300 can detect cognitive decline before the emergence of obvious neurological manifestations.

Objective:

The aim of this study is to assess and compare the P300 latencies in subjects with type 2 diabetes mellitus and in nondiabetic subjects and to determine the influence of type 2 diabetes mellitus on cognitive functions.

Materials and Methods:

In this study our sample size was 248 subjects, with type 2 diabetes mellitus patients (n = 124) and healthy controls (n = 124) between the age group of 31 and 60 years. This cross-sectional comparative study was conducted at SRM Medical College Hospital and Research Centre. The subjects were evaluated by a structured interview and they were assessed with a general health questionnaire to rule out any subpsychiatric illness. Fasting and postprandial blood glucose, HbA1c level, lipid profile, and creatinine were estimated. P300 amplitude and peak latencies were recorded using the standard auditory oddball paradigm.

Results:

The latencies of P300 were significantly increased and the amplitude of P300 was significantly reduced in the diabetic group when compared to the control group (P < .001). P300 latency has a positive correlation with the HbA1c levels (r = 0.136) and the duration of diabetes (r = 0.231).

Conclusion:

Prolongation of P300 latencies and the decreased amplitude in diabetic subjects may suggest the existence of a cognitive decline in individuals with type 2 diabetes compared to healthy individuals.

A review of electroencephalographic changes in diabetes mellitus in relation to major depressive disorder

A bidirectional relationship exists between diabetes mellitus (DM) and major depressive disorder (MDD), with depression commonly reported in both type 1 DM (T1DM) and type 2 DM (T2DM), and depressive symptoms associated with a higher incidence of diabetes. However, how the two conditions are pathologically connected is not completely understood. Similar neurophysiological abnormalities have been reported in both DM and MDD, including elevated electroencephalographic (EEG) activity in low-frequency slow waves and increased latency and/or reduced amplitude of event-related potentials. It is possible that this association reflects some common underlying pathology, and it has been proposed that diabetes may place patients at risk for depression through a biological mechanism linking the metabolic changes of DM to changes in the central nervous system. In this review we will discuss EEG abnormalities in DM, as well as the biological mechanisms underlying various EEG parameters, in order to evaluate whether or not a common EEG biosignature exists between DM and MDD. Identifying such commonalities could significantly inform the current understanding of the mechanisms that subserve the development of the two conditions. Moreover, this new insight may provide the basis for informing new drug discovery capable of mitigating and possibly even preventing both conditions.

The effects of C-peptide on type 1 diabetic polyneuropathies and encephalopathy in the BB/Wor-rat

Diabetic polyneuropathy (DPN) occurs more frequently in type 1 diabetes resulting in a more severe DPN. The differences in DPN between the two types of diabetes are due to differences in the availability of insulin and C-peptide. Insulin and C-peptide provide gene regulatory effects on neurotrophic factors with effects on axonal cytoskeletal proteins and nerve fiber integrity. A significant abnormality in type 1 DPN is nodal degeneration. In the type 1 BB/Wor-rat, C-peptide replacement corrects metabolic abnormalities ameliorating the acute nerve conduction defect. It corrects abnormalities of neurotrophic factors and the expression of neuroskeletal proteins with improvements of axonal size and function. C-peptide corrects the expression of nodal adhesive molecules with prevention and repair of the functionally significant nodal degeneration. Cognitive dysfunction is a recognized complication of type 1 diabetes, and is associated with impaired neurotrophic support and apoptotic neuronal loss. C-peptide prevents hippocampal apoptosis and cognitive deficits. It is therefore clear that substitution of C-peptide in type 1 diabetes has a multitude of effects on DPN and cognitive dysfunction. Here the effects of C-peptide replenishment will be extensively described as they pertain to DPN and diabetic encephalopathy, underpinning its beneficial effects on neurological complications in type 1 diabetes.

Auditory neuropathy in streptozotocin-induced diabetic mouse

An investigation of the mechanism of damage to the peripheral nervous system and central nervous system in diabetes mellitus (DM) is highly important in current neurological research. Auditory neuropathy is a hearing disorder in which the auditory brainstem evoked potential is absent or severely abnormal. This study investigated auditory neuropathy caused by streptozotocin in mouse model. In order to assess diabetic auditory neuropathy, we evaluated auditory brainstem response (ABR) for the evaluation of sensorineural function in peripheral auditory nerve. Auditory middle latency response (AMLR) was employed to assess the middle response in the midbrain. STZ groups significantly increased the absolute latencies IV and the interpeak latencies I-III and I-IV of ABR compared with STZ 0 group. Pa latency of AMLR also significantly increased in proportion to STZ dosage. Taken together, our results demonstrate that STZ-induced DM may impair the auditory pathway from peripheral auditory nerve to midbrain in the mouse model. We suggest that the STZ-induced diabetic mouse model may be useful for the evaluation of auditory pathway impairment by using ABR and AMLR tests.

Potencial cognitivo P300 em indivíduos com diabetes mellitus

Diabetes Mellitus pode acarretar complicações nos olhos, rins, nervos cranianos, nervos periféricos, ouvidos, etc. A função cognitiva também parece estar prejudicada em indivíduos portadores de Diabetes Mellitus, visto que as estruturas corticais e subcorticais responsáveis por esta função estão prejudicadas em alguns pacientes dependentes de insulina. O potencial cognitivo P300 tem sido usado como um procedimento objetivo para avaliar a função cognitiva cerebral. OBJETIVO: Analisar a sensibilidade do potencial cognitivo P300 para detectar alterações no córtex auditivo decorrentes do Diabetes Mellitus. FORMA DE ESTUDO: coorte transversal. MATERIAL E MÉTODO: Participaram deste estudo 16 indivíduos diabéticos de ambos os sexos, com idade variando de 7 a 71 anos, e 17 indivíduos não-diabéticos equiparados quanto ao sexo, idade e limiar auditivo. Os procedimentos de avaliação foram: Audiometria Tonal Liminar (ATL) e potencial cognitivo P300. No grupo diabético foi realizada a medida do valor glicêmico antes da realização do P300. RESULTADOS: Os resultados obtidos na ATL não mostraram diferença estatisticamente significante. Foi observado diferença estatisticamente significante entre os grupos, quando analisado a latência do componente P3, medido em Fz. Houve correlação entre a glicemia e a latência e amplitude do P300. CONCLUSÃO: A pesquisa do potencial cognitivo P300 é um importante procedimento para prevenir e diagnosticar precocemente de alterações neurológicas em indivíduos com Diabetes Mellitus.

The role of impaired insulin/IGF action in primary diabetic encephalopathy

We have previously shown that hippocampal neuronal apoptosis accompanied by impaired cognitive functions occurs in type 1 diabetic BB/Wor rats. To differentiate the contribution by insulin deficiency vs. that by hyperglycemia on neuronal apoptosis, we examined the activities of various apoptotic pathways in hippocampi from type 1 diabetic BB/Wor rats (hyperglycemic and insulinopenic) and type 2 diabetic BBZDR/Wor rats (hyperglycemic and hyperinsulinemic). DNA fragmentation was demonstrated by LM-PCR in type 1 diabetic BB/Wor rats, but was not detectable in duration- and hyperglycemia-matched type 2 BBZDR/Wor rats. Of various apoptotic pathways, Fas activations, 8-OHdG expression, and caspase-12 were demonstrated in type 1 diabetic BB/Wor rats only. In contrast, perturbations of the IGF and NGF systems and PARP activation were demonstrated in type 1 and to a lesser extent in type 2 diabetes. Expressions of Bax and active caspase-3 were significantly increased in type 1, but not in type 2, diabetic rats. These data suggest a lesser apoptogenic stress in type 2 vs. type 1 diabetes. These differences translated into a more profound neuronal loss in the hippocampus of type 1 rats. The results demonstrate that caspase-dependent apoptotic activities dominate in type 1 diabetes, whereas PARP-mediated caspase-independent apoptotic stress is present in both type 1 and type 2 diabetes. The findings suggest that insulin deficiency plays a compounding role to that of hyperglycemia in neuronal apoptosis underpinning primary diabetic encephalopathy.

Cognitive P300 potential in subjects with diabetes mellitus

Diabetes Mellitus may lead to alterations in the eyes, kidneys, cranial nerves, peripheral nerves, ears etc. The cognitive function also seems to be compromised in subjects presented with Diabetes Mellitus, since the cortical and subcortical structures responsible for this function are hindered in some insulin-dependent patients. The cognitive potential P300 has been used as an objective procedure to assess cerebral cognitive functions.

AIM

To analyze the sensitivity of P300 cognitive potential for the detection of alterations on the auditory cortex secondary to Diabetes Mellitus.

STUDY DESIGN

transversal cohort.

MATERIAL AND METHOD

Sixteen diabetic subjects of both genders aged 7 to 71 years, and seventeen non-diabetic individuals at the same age range participated in this study. The evaluation procedures were pure tone audiometry (PTA) and P300 cognitive potential. Glycemia of the group presented with Diabetes was assessed prior to applying P300.

RESULTS

No statistically significant difference was shown for PTA results. A statically significant difference was observed between groups when analyzing the latency of P300 component measured in Fz. There was a correlation between glycemia and latency and amplitude of P300.

CONCLUSION

The investigation of the cognitive potential of P300 is an important procedure for prevention and early diagnosis of neurological changes in individuals presented with Diabetes Mellitus.

Insulin, C-peptide, hyperglycemia, and central nervous system complications in diabetes

Diabetes is an increasingly common disorder which causes and contributes to a variety of central nervous system (CNS) complications which are often associated with cognitive deficits. There appear to be two types of diabetic encephalopathy. Primary diabetic encephalopathy is caused by hyperglycemia and impaired insulin action, which evolves in a diabetes duration-related fashion and is associated with apoptotic neuronal loss and cognitive decline. This appears to be particularly associated with insulin-deficient diabetes. Secondary diabetic encephalopathy appears to arise from hypoxic-ischemic insults due to underlying microvascular disease or as a consequence of hypoglycemia. This type of cerebral diabetic complication is more common in the type 2 diabetic population. Here, we will review the clinical and experimental data supporting this conceptual division of diabetic CNS complications and discuss the underlying metabolic, molecular, and functional aberrations.

Auditory event-related brain potentials in fibromyalgia syndrome

OBJECTIVE

The aim of this study was to investigate cognitive functions using auditory event-related brain potentials (ERP) in fibromyalgia syndrome (FMS).

METHODS

The P300 component of ERP was studied in 36 female FMS patients and 22 control subjects. The short form 36 (SF-36) medical outcome study was used to determine quality of life. Number of tender points and disease duration were noted. Cognitive functions were evaluated with P300.

RESULTS

The symptoms were discrepant in FMS (P<0.001). The scores of the eight SF-36 subgroups in FMS patients were significantly lower than in the control group (P<0.001). Fibromyalgia syndrome patients had prolonged latency and reduced amplitude of P300 (P<0.001). No correlation was found between the subgroups of SF-36, tender point count, disease duration, and P300.

CONCLUSION

The results of our study reveal that FMS affects quality of life and dysfunction in cognitive abilities can be determined by brain event-related potentials.

P300 (Latency) Event-Related Potential: An Accurate Predictor of Memory Impairment

To determine if P300 latency changes precede and correlate with memory and mental status, patients (N=1506 aged 20–100 years) who received medical and psychiatric diagnoses (from 1997 to 2002), were assessed for P300 (N=1496), WMS-III (N=694), and MMSE (N=456). Patient and control groups included, a) normal WMS-III on all 4 subscales (N=36), b) normal WMS-III and MMSE (N=189) with subjective memory/mental status complaints, and c) medical patients with normal WMS-III and no memory complaints (N=205), and d) P300 control group without medical, psychiatric or memory problems for ROC.

Patients with impaired/borderline memory had a prolonged P300 latency (P<0.02) compared to age matched non-impaired controls; in patients with normal WMS-III/MMSE, with subjective mild memory/mental status impairment, P300 latency was prolonged compared to controls (P=0.0004). The P300 latency increased by 0.72ms per year (P=7.9×10−65) and voltage decreased by 0.03dV per year (P=6.7×10−10), and both parameters were linearly correlated with the age of the subjects.

Male subjects had an average voltage of 6.1dV and female 6.8dV(P=0.00009). Statistically, prolonged latency began at age range 41–50 (P=0.0002); reduced P300 voltage began at age range 51–60 (P=0.003). WMS-III memory decline for all measures began in females at age range 61–70 (P value at least=0.02) and for males at age range 61–80 (P=0.02). Prolonged P300 latency (P≤0.0001) and memory impairment (at least <0.02) were greater for females than males. MMSE memory decline, male and female, began at age range 81–90 (P value of at least 0.00007).

In our logistic regression model P300 latency was more predictive of WMS-III impairment than MMSE >24. In patients whose WMS-III score is impaired ≤69, or borderline ≤79 (P at least =0.004), a P300 latency more prolonged than the norm (≥300 + 30 + Age) identifies these patients, whereas a MMSE >24 failed. With the ROC curve, we confirmed that P300 latency could accurately identify borderline/impaired memory.

Cognitive function and information processing in type 2 diabetes

AIMS

To determine whether uncomplicated Type 2 diabetes is associated with impairment of cognitive function and information processing ability.

METHODS

Thirty-eight participants with uncomplicated Type 2 diabetes and 38 non-diabetic controls were studied. The two groups were comparable for age and premorbid intellectual ability, and did not have other medical disorders likely to affect cognitive function. An extensive battery of tests was administered which assessed different levels and domains of cognitive functions including verbal and visual memory, executive function, general mental ability and efficiency of information processing.

RESULTS

No significant differences were found between the diabetic and control groups on any measure of cognitive function or information processing. The performance on these tests was not associated with recent glycaemic control (assessed by HbA1c). Duration of diabetes, however, correlated significantly with poorer performance on several measures of verbal memory.

CONCLUSIONS

The results of the present study suggest that some aspect of Type 2 diabetes (as indexed by the estimated duration of the disorder) does relate significantly to cognitive function within the group with diabetes. However, other diabetes-related factors, such as macrovascular disease, hypertension and depression, may contribute more to previously observed cognitive decrements in Type 2 diabetes.

Improvement of P300 latency by treatment in non-insulin-dependent diabetes mellitus

P300 event-related potentials were investigated in 24 cases of non-insulin-dependent (Type II) diabetes mellitus (NIDDM) without apparent central nervous system (CNS) symptoms and without cerebrovascular diseases on head magnetic resonance imaging, and in 16 age-matched healthy control subjects. N200 and P300 latencies were significantly prolonged and N200 and P300 amplitudes were significantly smaller in the NIDDM group than in the healthy control group. P300 latency was significantly shorter after the treatment than before. N200 and P300 waves have been recognized as useful indicators of cognitive function. The present study suggests that cognitive function is impaired in NIDDM patients and may improve with treatment of hyperglycemia.