Abstracts
Objective
To investigate the relationships between quality of life (QOL) and clinical and electroencephalogram (EEG) aspects in patients with Alzheimer’s disease (AD).
Method
Twenty-eight patients with mild or moderate AD, 31 with Parkinson’s disease (PD), and 27 normal controls (NC) were submitted to: CERAD neuropsychological battery, Hamilton Depression and Anxiety Rating Scales, Functional Activities Questionnaire, QOL scale for patients with AD, and quantitative EEG measures.
Results
AD and PD patients had similar QOL (31.0 ± 5.8; 31.7 ± 4.8, respectively), worse than that of NC (37.5 ± 6.3). AD patients had lower global interhemispheric theta coherence (0.49 ± 0.04; 0.52 ± 0.05; 0.52 ± 0.05; respectively) than PD and NC. Multiple linear regression for QOL of AD patients revealed that global interhemispheric theta coherence, and Hamilton depression scores were significant factors (coefficients; 58.2 and -0.27, respectively; R2, 0.377).
Conclusion
Interhemispheric coherence correlates with QOL regardless of cognitive and functional variables and seems to be a neurophysiological indicator of QOL in AD patients.
Alzheimer’s disease; EEG; quality of life; Parkinson’s disease
Objetivo
Investigar relações entre qualidade de vida (QV) e aspectos clínico-eletrencefalográficos (EEG) em pacientes com doença de Alzheimer (DA).
Método
Vinte e oito pacientes com DA, 31 com doença de Parkinson (DP) e 27 controles normais (CN) foram submetidos a avaliações neurocognitivas, escala de depressão de Hamilton e de qualidade de vida para pacientes com DA, questionário de atividades funcionais e medidas do EEG.
Resultados
A QV foi similar nos grupos DA e DP (31,0 ± 5,8; 31,7 ± 4,8, respectivamente), mas inferior ao CN (37,5 ± 6,3). No grupo DA houve menor coerência inter-hemisférica global teta (CIGT) do que em DP e CN (p < 0,05). Regressão múltipla linear para QV no grupo DA revelou a CIGT e a escala de Hamilton como fatores significativos (coeficientes; 58,2; -0,27, respectivamente; R2, 0,377).
Conclusão
A CIGT correlaciona-se com a QV independentemente de variáveis cognitivas e funcionais e parece ser um indicador neurofisológico da QV em pacientes com DA.
doença de Alzheimer; EEG; qualidade de vida; doença de Parkinson
Alzheimer’s disease (AD), a chronic and progressive disease, is the most common neurodegenerative illness in older people, and its prevalence is increasing because of higher life expectancy. AD causes cognitive and behavioral decline, compromising the ability of an individual to carry out activities of daily living and to work, and thereby has major psychosocial and quality of life (QOL) repercussions.
The clinical manifestations of Parkinson’s disease (PD) are essentially motor, but
cognitive and behavioral disturbances also occur, characterizing dementia in
approximately 30% of the cases11 Tedrus GMAS, Fonseca LC, Kange PM. Parkinson´s disease: impact of
clinical and cognitive aspects on quality of life. Dement Neuropsychol.
2010;4(2):131-7.,22 Tedrus GMAS, Fonseca LC, Letro GH, Bossoni AS. Samara AB. Dementia
and mild cognitive impairment in patients with Parkinson’s disease. Arq
Neuropsiquiatr. 2009;67(2B):423-7.
http://dx.doi.org/10.1590/S0004-282X2009000300010
https://doi.org/10.1590/S0004-282X200900...
.
Today the most common and well-known definition of QOL is that of the World Health
Organization (WHO), which defines it as an individual’s perception of his position in
life in the context of the culture and value systems in which he lives and in relation
to his goals, expectations, standards, and concerns33 World Health Organization Quality of Life Group - WHOQOL Group. The
World Health Organization Quality of Life assessment (WHOQOL): position paper
from the World Health Organization. Soc Sci Med. 1995;41(10):1403-9.
http://dx.doi.org/10.1016/0277-9536(95)00112-K
https://doi.org/10.1016/0277-9536(95)001...
.
In people with dementia, QOL is not an isolated concept among many measurements but the
main objective of professional care44 Banerjee S, Smith SC, Lamping DL, Harwood RH, Foley B, Smith P et
al. Quality of life in dementia: more than just cognition: an analysis of
associations with quality of life in dementia. J Neurol Neurosurg Psychiatry.
2006;77(2):146-8. http://dx.doi.org/10.1136/jnnp.2005.072983
https://doi.org/10.1136/jnnp.2005.072983...
.
Logsdon et al.55 Logsdon RG, Gibbons LE, McCurry SM, Teri L. Assessing quality of
life in older adults with cognitive impairment. Psychosom Med. 2002;64(3):510-9.
http://dx.doi.org/10.1097/00006842-200205000-00016
https://doi.org/10.1097/00006842-2002050...
used the Quality of
Life-Alzheimer’s disease (QOL-AD) psychometric analysis in a large sample of AD patients
and their caregivers and found that is possible for patients with a Mini-Mental State
Examination (MMSE) score greater than 10 to reliably and validly rate their own QOL. QOL
assessment has been used by studies on the care and treatment of AD patients66 Takeda A, Loveman E, Clegg A, Kirby J, Picot J, Payne E et al. A
systematic review of the clinical effectiveness of donepezil, rivastigmine and
galantamine on cognition, quality of life and adverse events in Alzheimer’s
disease. Int J Geriatr Psychiatry. 2006;21(1):17-28.
http://dx.doi.org/10.1002/gps.1402
https://doi.org/10.1002/gps.1402...
,77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
.
By assessing electrical brain activity, electroencephalograms (EEG) have many clinical applications, are inexpensive and risk-free, and many quantitative (qEEG) analyses became possible after the development of digital EEG. Some of these analyses include analysis of absolute power in different frequency bands of brain rhythms and analysis of coherence.
Analysis of absolute power reveals the increases in theta and delta activities and
decreases in alpha and beta powers that occur in AD patients88 Chiaramonti R, Muscas GC, Paganini M, Müller TJ, Fallgatter AJ,
Versari A et al. Correlations of topographical EEG features with clinical
severity in mild and moderate dementia of Alzheimer type. Neuropsychobiology.
1997;36(3):153-8. http://dx.doi.org/10.1159/000119375
https://doi.org/10.1159/000119375...
, and analysis of coherence shows the temporal
relationships between different regions, that is, it measures functional connectivity
between regions99 Thatcher RW, North D, Biver C. EEG and intelligence: relations
between EEG coherence, EEG phase delay and power. Clin Neurophysiol.
2005;116(9):2129-41.
http://dx.doi.org/10.1016/j.clinph.2005.04.026
https://doi.org/10.1016/j.clinph.2005.04...
. In patients with mild
cognitive impairment or AD/PD dementia, absolute power and coherence measurements
correlate significantly with performance in neuropsychological tests1010 Fonseca LC, Tedrus GMAS, Letro GH, Bossoni AS. Dementia, mild
cognitive impairment and quantitative EEG in patients with Parkinson’s disease.
Clinical EEG Neurosci. 2009;40(3):168-72.
http://dx.doi.org/10.1177/155005940904000309
https://doi.org/10.1177/1550059409040003...
,1111 Fonseca LC, Tedrus GM, Prandi LR, Almeida AM, Furlanetto DS.
Alzheimer’s disease: relationship between cognitive aspects and power and
coherence EEG measures. Arq Neuropsiquiatr. 2011;69(6):875-81.
http://dx.doi.org/10.1590/S0004-282X2011000700005
https://doi.org/10.1590/S0004-282X201100...
.
Resting state with eyes closed qEEG may show the degenerative changes caused by AD and is
considered a noninvasive method for diagnosing and assessing dementia66 Takeda A, Loveman E, Clegg A, Kirby J, Picot J, Payne E et al. A
systematic review of the clinical effectiveness of donepezil, rivastigmine and
galantamine on cognition, quality of life and adverse events in Alzheimer’s
disease. Int J Geriatr Psychiatry. 2006;21(1):17-28.
http://dx.doi.org/10.1002/gps.1402
https://doi.org/10.1002/gps.1402...
.
Depression and changes in the MMSE and Instrumental Activities of Daily Living are
important factors associated with QOL in AD patients77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
,1212 Conde-Sala JL, Garre-Olmo J, Turró-Garriga O, López-Pousa S
Vilalta-Franch J. Factors related to perceived quality of life in patients with
Alzheimer’s disease: the patient´s perception compared with that of caregivers.
Int J Geriatr Psychiatry. 2009;24(6):585-94.
http://dx.doi.org/10.1002/gps.2161
https://doi.org/10.1002/gps.2161...
. However, knowledge about QOL factors in AD is limited. Linear
regression analysis assessing these factors has shown that the self-rating QOL model
explains less than 50% of the variance44 Banerjee S, Smith SC, Lamping DL, Harwood RH, Foley B, Smith P et
al. Quality of life in dementia: more than just cognition: an analysis of
associations with quality of life in dementia. J Neurol Neurosurg Psychiatry.
2006;77(2):146-8. http://dx.doi.org/10.1136/jnnp.2005.072983
https://doi.org/10.1136/jnnp.2005.072983...
,77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
.
This study hypothesizes that qEEG variables can contribute to the neurophysiological basics of AD and better characterize QOL-related factors. There are no such studies in the literature.
The objective of this study was to investigate possible relationships between QOL and qEEG analyses of absolute power and coherence in AD patients and compare them with those of PD patients and normal controls.
METHOD
Subjects
This study included a group of AD patients and two control groups, one with Parkinson’s disease patients and another with individuals without neurological or psychiatric changes:
-
Group with AD included 28 patients that meet the DSM IV (American Psychiatric Association, 1994)1313 American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 4th ed. Washington, DC: American Psychiatric Association; 1994. criteria for dementia and the NINCDS/ADRDA criteria for probable AD1414 McKhann G, Drachman D, Folstein M, Katzman T, Price D, Stadlan EM. Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task force on Alzheimer’s disease. Neurology. 1984;34(7):939-44. http://dx.doi.org/10.1212/WNL.34.7.939
https://doi.org/10.1212/WNL.34.7.939... . The exclusion criteria were scoring less than eleven in the MMSE, indicative of severe dementia, taking antipsychotics, and having comorbidities that reduce life expectancy significantly. Twelve patients were on acetylcholinesterase inhibitors and four were on antidepressants. They were all living at home; -
Group with PD included 31 patients with clinical diagnosis of probable PD according to the criteria provided by Calne et al.1515 Calne DB, Snow BJ, Lee C. Criteria for diagnosing Parkinson’s disease. Ann Neurol. 1992;32(S1 Suppl):S125-7. http://dx.doi.org/10.1002/ana.410320721
https://doi.org/10.1002/ana.410320721... . All patients were on L-dopa and were evaluated in the on phase; -
Normal control (NC) group included 27 individuals without any history of cognitive decline or previous neurological or psychiatric disorder, matched with the AD group for gender distribution, age, and education level.
All study participants were recruited at the outpatient clinics of the Hospital e Maternidade Celso Pierro of PUC-Campinas and had a closely related informant available.
Procedures
The patients and controls were submitted to the following procedures:
clinical-neurological assessment; CERAD neuropsychological battery (Consortium
to establish a registry for Alzheimer’s Disease); Pfeffer functional activities
questionnaire; Neuropsychiatric Inventory; Hamilton Depression Rating Scale
(HDRS)1616 Hamilton M. A rating scale for depression. J Neurol Neurosurg
Psychiatry. 1960;23(1):56-62.
http://dx.doi.org/10.1136/jnnp.23.1.56
https://doi.org/10.1136/jnnp.23.1.56...
; Clinical
Dementia Rating – CDR; executive function tests, Quality of life scale in
Alzheimer’s disease (QOL-AD), and qEEG.
The Neuropsychiatric Inventory assesses 10 behavioral disturbances present in patients with dementia: delusions, hallucinations, dysphoria, anxiety, agitation/aggression, euphoria, disinhibition, irritability/lability, apathy, and aberrant motor activity. The score of each item is given by multiplying the frequency (range 1-4) by the severity (range 1-3), and the total score is given by adding the individual item scores.
The Pfeffer functional activities questionnaire investigates the patients’
ability to carry out activities of daily living. The score reflects the severity
of disability in each activity. Scores higher than five indicate functional
impairment. The instrument has been validated for the Brazilian population1717 Herrera Jr EJ, Caramelli P, Silveira AS, Nitrini R. Epidemiologic
survey of dementia in a community-dwelling Brazilian population. Alzheimer Dis
Assoc Disord. 2002;16(2):103-8.
http://dx.doi.org/10.1097/00002093-200204000-00007
https://doi.org/10.1097/00002093-2002040...
.
QOL was assessed by the patient’s version of the QOL scale for Alzheimer’s
disease developed by Logsdon et al.55 Logsdon RG, Gibbons LE, McCurry SM, Teri L. Assessing quality of
life in older adults with cognitive impairment. Psychosom Med. 2002;64(3):510-9.
http://dx.doi.org/10.1097/00006842-200205000-00016
https://doi.org/10.1097/00006842-2002050...
, adapted and validated for the Brazilian
population1818 Novelli MM, Nitrini R, Caramelli P. Validation of the Brazilian
version of the quality of life scale for patients with Alzheimer’s disease and
their caregivers (QOL-AD). Aging Ment Health. 2010;14(5):624-31.
http://dx.doi.org/10.1080/13607861003588840
https://doi.org/10.1080/1360786100358884...
. The scale,
structured with simple language and straightforward answers, was designed to
minimize the effects of the cognitive decline in AD. The patients answered the
questions during an interview, answering thirteen 4-point Likert-type questions
(1 = poor and 4 = excellent). The total score ranges from 13 to 52. Although
QOL-AD may also be administered to caregivers, this study administered the
instrument only to patients (QOL self-ratings) to investigate their perception
and related it directly to the qEEG.
Brain computed tomography or magnetic resonance imaging and laboratory testing were also carried out on the patients to rule out other causes of dementia and symptomatic Parkinsonism.
Electroencephalogram
The EEG procedures were the same as those used previously in another study1919 Fonseca LC, Tedrus GMAS, Carvas PN, Machado ECFA. Comparison of
quantitative EEG between patients with Alzheimer’s disease and those with
Parkinson´s disease dementia. Clin Neurophysiol. 2013;124(10):1970-4.
http://dx.doi.org/10.1016/j.clinph.2013.05.001
https://doi.org/10.1016/j.clinph.2013.05...
that addressed other
questions, had distinct purposes, and made other original scientific
contributions.
The EEG was recorded with a resolution of 12 bits, 0.5-35 Hz filters and 200 samples per second, using the Braintech 3.0 equipment (EMSA), with impedance maintained below 10 kΩ. The exam was carried out with the patients lying on their backs, in a silent environment with low intensity lighting. The electrodes were placed according to the International 10-20 System, with the use of an additional two electrodes placed 1 cm below (left side) and above (right side) the external angle of the eyelid, with the objective of evaluating eye movements. The data referring to the electrodes Fp1, Fp2, F8, and F7 were not computed due to frequent contamination by artifacts related to eye movements. The inter-connected ear lobe electrodes served as the reference. The data were recorded during approximately 12 minutes, alternating resting periods with eyes closed with alert periods when the eyes were open, each period lasting 2 minutes. The individual was stimulated to remain awake when symptoms of somnolence appeared. Stretches of somnolence or sleep were excluded from the quantitative analysis.
About 25 epochs were selected for the quantitative EEG while alert and resting
(eyes closed), each lasting 2.56 s. Epochs with more than 100 µV on the
electro-oculogram were excluded from the means. After applying the Fast Fourier
Transform, the absolute powers (microvolts22 Tedrus GMAS, Fonseca LC, Letro GH, Bossoni AS. Samara AB. Dementia
and mild cognitive impairment in patients with Parkinson’s disease. Arq
Neuropsiquiatr. 2009;67(2B):423-7.
http://dx.doi.org/10.1590/S0004-282X2009000300010
https://doi.org/10.1590/S0004-282X200900...
/Hz) of 17 electrodes were studied (Fp2, Fp1 and Oz
were not included) in the following frequency bands: delta (0.8 to 3.9 Hz),
theta (4.29 to 7.8 Hz), alpha (8.2 to 12.5 Hz) and beta (12.9 till 36.3 Hz). To
obtain a normal distribution, the values for absolute power were substituted by
their logarithms.
The absolute power averages were calculated for all the electrodes together (global averages).
To analyze for coherence, this was defined as:
Where Gxy(f) denotes the spectral density of the cross-power and Gxx(f) and Gyy(f) are the respective spectral densities of the power. The interhemispheric coherences between the following pairs of homologue electrodes were calculated: frontal left-right (F3-F4); mid temporal left-right (T3-T4) and occipital left-right (O1-O2). The global averages for interhemispheric coherence were also calculated. The frontal-occipital (F4-O2, F3-O1) average coherence was measure for the intrahemispheric delta, theta, alpha and beta band coherences.
Individuals in the NC group underwent anamnesis, neurological examination, neurocognitive and behavioral assessments, and qEEG.
Data analysis
The continuous variables were expressed as mean and standard deviation (SD), and the categorical variables were expressed as frequencies (%). The student’s t-test, analysis of variance (ANOVA), and Pearson Chi-squared test were used to compare the continuous variables and categorical variables.
Multiple regression were used to determine the relationship between predictor variables and continuous outcome variables (dependent variables) using variables with p < 0.10 in the respective prior correlation analyses (independent variables). The data were treated by the software Statistical Package for the Social Sciences (SPSS), version 22. The significance level was set at 5%.
The software IBM SPSS 20.0 determined how QOL-AD scores associated with the study cognitive and behavioral variables, and analyzed qEEG absolute power and coherence in the Groups AD, PD, and NC at a significance level of 5% (p < 0.05).
The effect size was measured by calculating Cohen’s
f 2 within a multiple
regression model2020 Cohen J. A power primer. Psychol Bull. 1992;112(1):155-9.
http://dx.doi.org/10.1037/0033-2909.112.1.155
https://doi.org/10.1037/0033-2909.112.1....
.
Approval by the Research Ethics Committee
The project was approved by PUC-Campinas’ Research Ethics Committee under protocol number no. 0433/11. Appropriate ethical safeguards and protocols have been followed including agreement of patients or their relatives.
RESULTS
Sociodemographic and clinical aspects
Table 1 shows the sociodemographic data and results of the Mini-Mental State Examination, semantic verbal fluency, Neuropsychiatric Inventory, Pfeffer functional activities questionnaire, and QOL-AD of the AD, PD, and NC groups.
Age, gender, education level, Mini-Mental State Examination, verbal fluency, Pfeffer functional activities questionnaire, Neuropsychiatric Inventory, Hamilton Depression Scale and Quality of Life – Alzheimer’s Disease Patient’s Version (QOL-AD) for the Alzheimer’s disease (AD), Parkinson’s disease (PD), and normal control (NC) groups.
The ages and gender distribution of the AD and NC groups did not differ significantly. However, the education level of the AD group was significantly lower than that of the NC (t-test, p < 0.05).
The AD group performed worse in the MMSE and verbal fluency test than the PD and NC groups (t-test, p < 0.05).
The AD group scored higher in the functional activities questionnaire than the PD and NC groups. However, the AD and PD groups scored similarly in the Hamilton Depression Scale and Neuropsychiatric Inventory; their scores were higher than those of the NC group (t-test, p < 0.05).
The NC group had higher QOL-AD scores than the AD and PD groups. The scores of the latter two were similar (t-test, p < 0.05).
Qualitative electroencephalogram
Comparative analysis of global absolute powers (delta, theta, alpha, and beta) showed that the theta band of the AD group was higher than that of the NC but the difference was not significant (t-test, p = 0.079). The AD and PD theta bands did not differ (data not shown).
The delta, theta, alpha, and beta frontal-occipital (F4-O2, F3-O1) means of the AD, PD, and NC groups did not differ.
Table 2 shows that the mean global interhemispheric theta, alpha, and beta coherences of the AD group were smaller than those of the PD and NC groups (t-test, p < 0.05).
Correlations between quality of life and qEEG
Pearson’s correlation coefficients between the QOL-AD scale scores and the main cognitive, behavioral, and functional variables were calculated, as well as between the qEEG variables of the three groups (Table 3).
In the AD group, QOL-AD correlated positively with semantic fluency (CC = 0.472, p = 0.011). A significant negative correlation between The QOL-AD of the three groups correlated negatively with their Hamilton scale scores (CC = 458, p < 0.014). The QOL-AD of the PD and NC groups also correlated negatively with their Neuropsychiatric Inventory scores. QOL-AD did not correlate significantly with the age, educational level, Mini-Mental State Examination, Pfeffer Questionnaire, and Neuropsychiatric Inventory of the three groups.
The QOL-AD of the AD group correlated positively with their interhemispheric theta coherence (CC = 0.517, p = 0.005).
The qEEG and QOL-AD scores of the PD and NC groups did not show correlation.
The multiple regression equation for the AD group showed that the significant factors for QOL-AD were interhemispheric theta global coherence and Hamilton depression Scale score (p = 0.003) (Table 4). Age, education level, verbal fluency, Pfeffer Questionnaire score, and other qEEG measurements were excluded from the equation because they were not significant. The Cohen’s f 2 index of 0.605 is considered of large effect.
Multiple regression and Cohen’s f 2 index for the total Quality of Life – Alzheimer’s Disease (QOL-AD) scores: predictor variable with significant effects for the 28 patients with Alzheimer’s disease.
According to multiple regression, the the Hamilton Depression Scale score is the only significant factor for QOL-AD in the Groups PD and NC (p = 0.000 and p = 0.001, respectively).
DISCUSSION
This study confirmed, in an original way, the hypothesis that a qEEG variable is
associated with the QOL of AD patients regardless of cognitive and behavioral
aspects. This association was not observed in the NC group or in a group with
similar QOL deterioration, such as the PD group, whose physiopathology and qEEG
differ from those of AD patients1010 Fonseca LC, Tedrus GMAS, Letro GH, Bossoni AS. Dementia, mild
cognitive impairment and quantitative EEG in patients with Parkinson’s disease.
Clinical EEG Neurosci. 2009;40(3):168-72.
http://dx.doi.org/10.1177/155005940904000309
https://doi.org/10.1177/1550059409040003...
,1919 Fonseca LC, Tedrus GMAS, Carvas PN, Machado ECFA. Comparison of
quantitative EEG between patients with Alzheimer’s disease and those with
Parkinson´s disease dementia. Clin Neurophysiol. 2013;124(10):1970-4.
http://dx.doi.org/10.1016/j.clinph.2013.05.001
https://doi.org/10.1016/j.clinph.2013.05...
.
The present study corroborates the well-known fact that QOL is related to depression
and the Neuropsychiatric Inventory scores of patients with PD and normal
controls2121 Lemke MR. Depressive symptoms in Parkinson’s disease. European J
Neurol. 2008;15(S1 Suppl1):21-5.
http://dx.doi.org/10.1111/j.1468-1331.2008.02058.x
https://doi.org/10.1111/j.1468-1331.2008...
.
The present used the QOL-AD to investigate the patient’s perception of his situation
because it may differ from the caregiver’s perception, and the latter can be biased
by several factors77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
,1212 Conde-Sala JL, Garre-Olmo J, Turró-Garriga O, López-Pousa S
Vilalta-Franch J. Factors related to perceived quality of life in patients with
Alzheimer’s disease: the patient´s perception compared with that of caregivers.
Int J Geriatr Psychiatry. 2009;24(6):585-94.
http://dx.doi.org/10.1002/gps.2161
https://doi.org/10.1002/gps.2161...
,2222 Arons AM, Krabbe PF, Schölzel-Dorenbos CJ, Wilt GJ, Rikkert MG.
Quality of life in dementia: a study on proxy bias. BMC Med Res Methodol.
2013;13(1):110. http://dx.doi.org/10.1186/1471-2288-13-110
https://doi.org/10.1186/1471-2288-13-110...
.
The QOL-AD associated most significantly with the Hamilton Depression Rating Scale,
Neuropsychiatric Inventory, neuropsychological test that assesses various aspects of
orientation, memory, language, praxis, attention, and executive function, and Rating
of Awareness Deficits, even though they clear differ between studies77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
,1212 Conde-Sala JL, Garre-Olmo J, Turró-Garriga O, López-Pousa S
Vilalta-Franch J. Factors related to perceived quality of life in patients with
Alzheimer’s disease: the patient´s perception compared with that of caregivers.
Int J Geriatr Psychiatry. 2009;24(6):585-94.
http://dx.doi.org/10.1002/gps.2161
https://doi.org/10.1002/gps.2161...
,2323 Edelman P, Fulton BR, Kuhn D, Chang Ch, Chang C. A comparison of
three methods of measuring dementia-specific quality of life: perspectives of
residents, staff, and observers. Gerontologist. 2005;45(Suppl 1):27-36.
http://dx.doi.org/10.1093/geront/45.suppl_1.27
https://doi.org/10.1093/geront/45.suppl_...
. QOL is weakly correlated with cognition, and in some
studies behavioral and psychological disturbances are more strongly associated with
QOL than cognition or functional limitations44 Banerjee S, Smith SC, Lamping DL, Harwood RH, Foley B, Smith P et
al. Quality of life in dementia: more than just cognition: an analysis of
associations with quality of life in dementia. J Neurol Neurosurg Psychiatry.
2006;77(2):146-8. http://dx.doi.org/10.1136/jnnp.2005.072983
https://doi.org/10.1136/jnnp.2005.072983...
,1212 Conde-Sala JL, Garre-Olmo J, Turró-Garriga O, López-Pousa S
Vilalta-Franch J. Factors related to perceived quality of life in patients with
Alzheimer’s disease: the patient´s perception compared with that of caregivers.
Int J Geriatr Psychiatry. 2009;24(6):585-94.
http://dx.doi.org/10.1002/gps.2161
https://doi.org/10.1002/gps.2161...
,2323 Edelman P, Fulton BR, Kuhn D, Chang Ch, Chang C. A comparison of
three methods of measuring dementia-specific quality of life: perspectives of
residents, staff, and observers. Gerontologist. 2005;45(Suppl 1):27-36.
http://dx.doi.org/10.1093/geront/45.suppl_1.27
https://doi.org/10.1093/geront/45.suppl_...
. The patient’s QOL version also revealed associated
factors that explain higher variance percentages (48.3%) than the carer-patient QOL
ratings (37.5%)77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
.
In this study the QOL-AD ratings of AD patients were lower than those of NC and similar to those of PD patients. As mentioned previously, the study included sociodemographic, cognitive, and behavioral variables associated with QOL to investigate factors possibly associated with QOL-AD.
The QOL-AD of the AD group correlated negatively with depression symptoms, in a way
similar to other studies44 Banerjee S, Smith SC, Lamping DL, Harwood RH, Foley B, Smith P et
al. Quality of life in dementia: more than just cognition: an analysis of
associations with quality of life in dementia. J Neurol Neurosurg Psychiatry.
2006;77(2):146-8. http://dx.doi.org/10.1136/jnnp.2005.072983
https://doi.org/10.1136/jnnp.2005.072983...
,1212 Conde-Sala JL, Garre-Olmo J, Turró-Garriga O, López-Pousa S
Vilalta-Franch J. Factors related to perceived quality of life in patients with
Alzheimer’s disease: the patient´s perception compared with that of caregivers.
Int J Geriatr Psychiatry. 2009;24(6):585-94.
http://dx.doi.org/10.1002/gps.2161
https://doi.org/10.1002/gps.2161...
,2323 Edelman P, Fulton BR, Kuhn D, Chang Ch, Chang C. A comparison of
three methods of measuring dementia-specific quality of life: perspectives of
residents, staff, and observers. Gerontologist. 2005;45(Suppl 1):27-36.
http://dx.doi.org/10.1093/geront/45.suppl_1.27
https://doi.org/10.1093/geront/45.suppl_...
. However, the QOL-AD correlated positively with verbal
fluency, but this is hard to compare with other studies because other studies do not
show cognitive their test results; correlations between cognitive aspects and QOL
are uncommon77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
,99 Thatcher RW, North D, Biver C. EEG and intelligence: relations
between EEG coherence, EEG phase delay and power. Clin Neurophysiol.
2005;116(9):2129-41.
http://dx.doi.org/10.1016/j.clinph.2005.04.026
https://doi.org/10.1016/j.clinph.2005.04...
.
Other studies have not found associations between QOL-AD and the Pfeffer functional
activities questionnaire or the Neuropsychiatric Inventory77 Bosboom PR, Alfonso H, Eaton J, Almeida OP. Quality of life in
Alzheimer’s disease: different factors associated with complementary ratings by
patients and family carers. Int Psychogeriatr. 2012;24(5):708-21.
http://dx.doi.org/10.1017/S1041610211002493
https://doi.org/10.1017/S104161021100249...
.
The study AD group had smaller interhemispheric theta, alpha, and beta band
coherences than the NC group, a finding corroborated by the literature2020 Cohen J. A power primer. Psychol Bull. 1992;112(1):155-9.
http://dx.doi.org/10.1037/0033-2909.112.1.155
https://doi.org/10.1037/0033-2909.112.1....
,2424 Locatelli T, Cursi M, Liberati D, Franceschi M, Comi G. EEG
coherence in Alzheimer’s disease. Electroencephalogr Clin Neurophysiol.
1998;106(3):229-37.
http://dx.doi.org/10.1016/S0013-4694(97)00129-6
https://doi.org/10.1016/S0013-4694(97)00...
,2525 Besthorn C, Förstl H, Geiger-Kabisch C, Sattel H, Gasser T,
Schreiter-Gasser U. EEG coherence in Alzheimer disease. Electroencephalogr Clin
Neurophysiol.1994;90(3):242-5.
http://dx.doi.org/10.1016/0013-4694(94)90095-7
https://doi.org/10.1016/0013-4694(94)900...
,2626 Adler G. Brassen S, Jajcevic J. EEG coherence in Alzheimer’s
dementia. J Neural Transm. 2003;110(9):1051-8.
http://dx.doi.org/10.1007/s00702-003-0024-8
https://doi.org/10.1007/s00702-003-0024-...
,2727 Sancari Z, Adeli H, Adeli A. Intrahemispheric, interhemispheric, and
distal EEG coherence in Alzheimer’s disease. Clin Neurophysiol.
2011;122(5):897-906.
http://dx.doi.org/10.1016/j.clinph.2010.09.008
https://doi.org/10.1016/j.clinph.2010.09...
. Lower coherence in AD patients stems from the loss of
long corticocortical tracts necessary for functional interactions or from low
cholinergic coupling between cortical neurons2828 Jeong J. EEG dynamics in patients with Alzheimer disease. Clin
Neurophysiol. 2004;115(7):1490-1505.
http://dx.doi.org/10.1016/j.clinph.2004.01.001
https://doi.org/10.1016/j.clinph.2004.01...
. Cortical areas would be functionally disconnected,
which could be interpreted as neocortical “disconnection syndrome.” In AD patients
smaller alpha and beta band coherences are associated with worse cognitive
performance2525 Besthorn C, Förstl H, Geiger-Kabisch C, Sattel H, Gasser T,
Schreiter-Gasser U. EEG coherence in Alzheimer disease. Electroencephalogr Clin
Neurophysiol.1994;90(3):242-5.
http://dx.doi.org/10.1016/0013-4694(94)90095-7
https://doi.org/10.1016/0013-4694(94)900...
.
The possible mechanisms behind the positive correlations between global
interhemispheric coherence, specifically in the theta band, and QOL-AD deserve
investigation. In a masterful review, Klimesh2929 Klimesch W. EEG alpha and theta oscillations reflect cognitive and
memory performance: a review and analysis. Brain Res Rev. 1999;29(2-3):169-95.
http://dx.doi.org/10.1016/S0165-0173(98)00056-3
https://doi.org/10.1016/S0165-0173(98)00...
found different correlations between absolute theta
and alpha power oscillations in cognitive processing. Better performance in
cognitive tasks is related to two types of phenomena: one tonic, regarding an
increase in alpha and decrease in theta; and another phasic (event related),
regarding a decrease in alpha and an increase in theta, depending on the type of
memory used.
On the other hand, Stein and Sarnthein3030 Stein A, Sarnthein J. Different frequencies for different scales of
cortical integration: from local gamma to long range alpha/theta
synchronization. Int J Psychophysiol. 2000;38(3):301-13.
http://dx.doi.org/10.1016/S0167-8760(00)00172-0
https://doi.org/10.1016/S0167-8760(00)00...
emphasize that different electrical brain activity
frequencies are associated with different scales of cortical integration. These
authors found that local interactions during visual processing involve gamma
frequency dynamics, semantic interactions between the parietal and temporal cortices
involve beta frequency dynamics, and that long amplitude interactions during
internal mental processes involve theta or alpha frequencies. The concept of QOL is
speculated to depend on this broad and internal integration of components possibly
related to theta coherence.
The limitations of the present study included the relatively small number of cases and the heterogeneous use of acetylcholinesterase inhibitors and antidepressants medications in the Group AD. Still, the present findings are important and based on simple and easily available qEEG methods.
In conclusion, this is the first report of a relationship between low global interhemispheric theta-band coherence and low QOL-AD, regardless of cognitive and behavioral variables. This interhemispheric coherence can be objectively measured, and its correlation with QOL scores also contributes to the knowledge about the physiopathology of AD, probably related to impaired functional connection between broad cortical areas.
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Publication Dates
-
Publication in this collection
May 2015
History
-
Received
11 Oct 2014 -
Reviewed
20 Dec 2014 -
Accepted
08 Jan 2015