P300 Analysis Using High-Density EEG to Decipher Neural Response to rTMS in Patients With Schizophrenia and Auditory Verbal Hallucinations.

Schizophrenia is a complex disorder about which much is still unknown. Potential treatments, such as transcranial magnetic stimulation (TMS), have not been exploited, in part because of the variability in behavioral response. This can be overcome with the use of response biomarkers. It has been however shown that repetitive transcranial magnetic stimulation (rTMS) can the relieve positive and negative symptoms of schizophrenia, particularly auditory verbal hallucinations (AVH). This exploratory work aims to establish a quantitative methodological tool, based on high-density electroencephalogram (HD-EEG) data analysis, to assess the effect of rTMS on patients with schizophrenia and AVH. Ten schizophrenia patients with drug-resistant AVH were divided into two groups: the treatment group (TG) received 1 Hz rTMS treatment during 10 daily sessions (900 pulses/session) over the left T3-P3 International 10-20 location. The control group (CG) received rTMS treatment over the Cz (vertex) EEG location. We used the P300 oddball auditory paradigm, known for its reduced amplitude in schizophrenia with AVH, and recorded high-density electroencephalography (HD-EEG, 256 channels), twice for each patient: pre-rTMS and 1 week post-rTMS treatment. The use of HD-EEG enabled the analysis of the data in the time domain, but also in the frequency and source-space connectivity domains. The HD-EEG data were linked with the clinical outcome derived from the auditory hallucinations subscale (AHS) of the Psychotic Symptom Rating Scale (PSYRATS), the Quality of Life Scale (QoLS), and the Depression, Anxiety and Stress Scale (DASS). The general results show a variability between subjects, independent of the group they belong to. The time domain showed a higher N1-P3 amplitude post-rTMS, the frequency domain a higher power spectral density (PSD) in the alpha and beta bands, and the connectivity analysis revealed a higher brain network integration (quantified using the participation coefficient) in the beta band. Despite the small number of subjects and the high variability of the results, this work shows a robust data analysis and an interplay between morphology, spectral, and connectivity data. The identification of a trend post-rTMS for each domain in our results is a first step toward the definition of quantitative neurophysiological parameters to assess rTMS treatment.

Increased incidence of disability due to mental and behavioural disorders in Iceland 1990-2007.

AIMS: To explore longitudinal changes in the importance of mental and behavioural disorders and their subgroups among people receiving disability pension in Iceland in the period 1990 to 2007. METHOD: Estimation of the incidence of disability pension was based on national demographic data and information from the national disability register which includes the main diagnoses causing disability. RESULTS: The share of mental and behavioural disorders among new recipients of disability pension increased from 14 to 30% for women and 20 to 35% men. There was a marked increase in the incidence of disability due to disorders related to the use of alcohol and other psychoactive substances, mood disorders, disorders of psychological development and behavioural and emotional disorders with onset usually occurring in childhood and adolescence. The proportion of mental and behavioural disorders as the primary diagnosis among new recipients of disability pension increased. CONCLUSION: The most likely explanation for the changes we observe is alteration in social conditions leading to a lower threshold for seeking disability pension for mental disorders.

[Conversion disorder - review]. / Hugbrigdaröskun - yfirlitsgrein.

In modern medicine the term "functional symptoms" is usually used to refer to symptoms where an organic cause cannot be found. Studies have shown that up to half of all patients consulting their family physician and approximately one third of all those attending neurology outpatient clinics present with such symptoms. These patients commonly go between doctors, repeatedly undergo unnecessary tests, even surgery, and various drugs are tried with limited success. These problems tend to be prolonged and greatly reduce the quality of life for the patients involved. Both the DSM IV and ICD 10 classifications include a group for the so-called medically unexplained disorders. Among these disorders is conversion disorder where patients present with neurological symptoms, affecting motor or sensory function, but with no neurological explanation. Here we provide an overview of the current ideas on the aetiology, diagnosis, treatment and prognosis of conversion disorder.

[Prevalence of disability in Iceland in December 2005]. / Algengi örorku á Islandi 1. desember 2005.

OBJECTIVE: To determine the size and main medical and social characteristics of the group of individuals receiving disability benefits in Iceland in December 2005. MATERIAL AND METHODS: The study includes all those receiving disability benefits in Iceland on December 1st 2005 as ascertained by the disability register at the State Social Security Institute of Iceland classified by gender, age and place of residence. Similar information was obtained on the Icelandic population. The prevalence of disability pension was calculated. RESULTS: On December 1st 2005 the prevalence of disability pension was 8.6% for females (8.0% for the higher and 0.6% for the lower pension level) and 5.5% for males (5.2% for the higher and 0.3% for the lower pension level). For females the prevalence of disability was lower in the capital region than in other regions, but this was not the case for males. The prevalence of disability increased with age. On the whole disability was more common among females than males. Mental and behavioural disorders and diseases of the musculoskeletal system and connective tissue were the most prevalent causes of disability. CONCLUSION: The prevailing trend over the last decade of increasing disability in Iceland has continued. Iceland appears to lag behind the other Nordic countries in the use of vocational rehabilitation and labour marked activation to prevent disability. Ample opportunities to slow down this trend are therefore available by greater emphasis on such measures.

The effects of repetitive transcranial magnetic stimulation on depressive symptoms and the P(300) event-related potential.

Changes in the Hamilton Depression Rating Scale and the P(300) auditory event-related potential were assessed in 10 patients with depression before and after a treatment course of five daily sessions of 10 Hz repetitive transcranial magnetic stimulation (rTMS) over the left prefrontal cortex. The patients were initially randomly allocated either to an active or a placebo rTMS treatment. All patients received both types of treatment separated by an interval of 4 weeks. The median Hamilton score decreased by 7 points following active rTMS and by 1 point after sham (p=0.075). Active rTMS was associated with a significant increase in the P(300) amplitude compared with sham (p=0.02). There was no correlation between changes in P(300) measurements and the Hamilton scores after active treatment. We conclude that five daily sessions of left prefrontal rTMS treatment is not of sufficient duration to make a significant improvement in depressive symptoms.

[Prevalence of disability pension related to obesity in Iceland 1992-2004]. / Algengi offitugreiningar hjá öryrkjum á Islandi 1992-2004.

OBJECTIVES: To investigate changes in the prevalence of disability pension related to obesity in Iceland from 1992 to 2004. MATERIAL AND METHODS: Data were obtained from the disability register of the State Social Security Institute and Statistics Iceland for the years 1992 and 2004. Prevalence of disability pension related to obesity and of disability pension in general was calculated for both years. Statistical significance was assessed by calculating chi square and standardized risk ratios. RESULTS: From 1992 to 2004 the number of recipients of disability pension with obesity as a primary diagnosis increased from 37 to 111, amounting to 183% increase for females and 263% for males. This increase is significantly greater than the increase in disability pension in general during this period. Age standardized risk ratio showed increased disability related to obesity for both genders. Among males it was greater than the general increase in disability, while among females it was less. There was a significantly greater increase in disability related to obesity in areas outside the capital compared with Reykjavík and surrounding areas among females. The increase in disability related to obesity far surpasses the increase in obesity in the population, according to population surveys, suggesting that severe and morbid obesity may be particularly on the rise. CONCLUSION: There has been a significant increase in the prevalence of disability pension related to obesity in Iceland from 1992 to 2004. It is possible that increased social awareness of obesity during the study period has influenced diagnostic habits of physicians and thus increased the use of obesity as a diagnosis in medical certificates and disability assessment. In all likelihood, however, there has been an increase in disabling obesity in Iceland, indicating that obesity is an increasing public health problem demanding appropriate intervention.

[Prevalence of disability in Iceland in December 2002.].

OBJECTIVE: To determine the size and main medical and social characteristics of the group of individuals receiving disability benefits in Iceland in December 2002 and compare the results with figures from 1996. MATERIAL AND METHODS: The study includes all those receiving disability benefits on December 1st 2002 and December 1st 1996 as ascertained by the disability register at the State Social Security Institute of Iceland. Information on age and gender distribution of the Icelandic population was obtained. Age-standardized risk ratio between the years 1996 and 2002 was calculated for both pension levels combined and for full disability pension alone. RESULTS: On December 1st 2002 there were 11,791 individuals receiving disability benefits, 7044 women (59.7%) and 4747 men (40.3%). Of these there were 10,960 individuals receiving full disability pension, 6500 women (59.3%) and 4460 men (40.7%). The prevalence of all disability pension was 6.2%; full disability pension 5.8% and partial disability pension 0.4%. The prevalence of disability was lower in the capital region compared with other regions of Iceland among women, but among men there was no significant difference in the prevalence of disability according to residence. The prevalence of disability increased with age. On the whole disability was more common among women than men, but in the age group 16-19 years it was more common among men than women. Mental and behavioural disorders and diseases of the musculoskeletal system and connective tissue were the most prevalent causes of disability. The standardized risk ratio showed a significantly increased risk for both pension levels combined and for full disability pension alone both for men and women in the year 2002 as compared with the year 1996. CONCLUSION: The increase in the prevalence of disability in Iceland between the years 1996 and 2002 is probably mainly due to the introduction of a new method of disability evaluation in 1999 and increased pressure from the labour market, with increasing unemployment and competition. Mental and behavioural disorders are the most common cause of disability in Iceland and there has been a marked increase in disability due to these disorders since 1996.

[Disability due to mental and behavioural disorders in Iceland.].

AIMS: To determine the prevalence of disability in Iceland on December 1st 2002 due to mental and behavioural disorders according to gender, place of residence and marital status and main subcategories. MATERIAL AND METHODS: The disability register of the State Social Security Institute was used to obtain information on the number, gender, age, place of residence, marital status and main diagnosis of recipients of disability pension. From Statistics Iceland the same information was obtained for the Icelandic population between the age of 16 and 66. RESULTS: The prevalence of disability due to mental and behavioural disorders was 2.32% for females and 1.98% for males. For males receiving disability pension the proportion having mental disorders as the main cause of disability was larger than for females. Among females the most common cause of disability was mood disorders whereas among males it was schizophrenia, schizotypal and delusional disorders. Most of those with schizophrenia, schizotypal and delusional disorders in Iceland receive full disability pension. The prevalence of disability due to mental and behavioural disorders was significantly higher in the capital region than in the rest of the country. Marriage and registered co-habitation was considerably less common among recipients of disability pension due to mental and behavioural disorders than among the nation in general. CONCLUSION: The prevalence of disability due to mental and behavioural disorders in the capital region is in excess of what is to be expected from the prevalence of these disorders and from disability in general in Iceland. The relatively high prevalence of disability due to mental and behavioural disorders among males is in line with epidemiological data. The prevalence of disability due to mental and behavioural disorders in Iceland has been rising. This needs to be addressed by improving vocational rehabilitation programs for those suffering from these disorders.

[Comparison of the first medical assessment for rehabilitation benefits and disability pension in Iceland September 1st 1999 to November 30th 2003.].

AIMS: To evaluate the main characteristics which differentiate between those who are considered to benefit from rehabilitation and those for whom disability pension is thought more appropriate. MATERIAL AND METHODS: The study includes all those fulfilling the medical criteria for rehabilitation benefits or full disability pension in their first assessment at the State Social Security Institute of Iceland between September 1st 1999 and November 30th 2003. RESULTS: Rehabilitation benefits were mainly awarded in younger age groups; disability pension in older age groups. Mental and behavioural disorders were the most common medical reasons for granting rehabilitation benefits among both genders, followed by disorders of the musculoskeletal system and connective tissue, malignant neoplasms and injuries. Among females disorders of the musculoskeletal system and connective tissue were the most common medical reason for granting full disability pension, but this group of disorders was a less common reason for rehabilitation benefits. Those who fulfilled the medical criteria for rehabilitation benefits due to disorders of the musculoskeletal system and connective tissue were markedly older than those who fulfilled the medical criteria for rehabilitation benefits due to mental and behavioural disorders. CONCLUSION: In Iceland rehabilitation benefits are most likely to be awarded to relatively young claimants suffering from psychiatric disorders.

[Transcranial magnetic stimulation.].

Transcranial Magnetic Stimulation (TMS) is a new non-invasive method to investigate the central nervous system. Initially it was used to assess the functional integrity of the pyramidal pathways but more recently various other aspects of brain function have been studied including cortical excitability. By localised interference with brain function, it is possible to use TMS to assess the relationship between various brain regions and cognitive functions. The therapeutic effect of TMS has been explored in the treatment of neurological diseases and psychiatric disorders such as epilepsy, cerebellar ataxia and depressive illness.

[Relationship between rate of unemployment and incidence of disability pension in Iceland 1992-2003.].

OBJECTIVE: To evaluate the effect of unemployment and the introduction of a new method of disability assessment on the number of recipients of disability pension in Iceland by examining changes in the incidence of disability pension and unemployment year by year from 1992 to 2003. MATERIAL AND METHODS: Information on gender, age and disability grade of new recipients of disability pension in Iceland and corresponding information on the Icelandic population for each year in the period 1992 to 2003 was used to calculate the incidence of disability pension. The results were compared with data on the rate of unemployment in Iceland. RESULTS: The incidence of disability pension was relatively high from 1992 to 1995, was lower from 1996 to 2002 and then increased markedly in 2003. There is a strong correlation between the incidence of disability pension and the rate of unemployment among both genders in Iceland during the period covered by the study. An increase from 1999 to 2000 in the incidence of disability pension among females coincided in time with the introduction of a new method of disability assessment in September 1999, but also with an increase in the rate of unemployment among females. CONCLUSION: It is not warranted to claim that the introduction of a new method of disability evaluation in September 1999 has resulted in a decisive increase in the incidence of disability pension in Iceland. The increase in the number of recipients of disability pension in Iceland recently has a strong statistical correlation with changes in the labour marked, especially with rising unemployment and increased pressure at work.

[Fibromyalgia and anxiety disorder.].

OBJECTIVE: The etiology of fibromyalgia is unclear. The diagnosis is based on widespread pain and muscular tenderness, but other symptoms often occur, such as sleep disturbance, excessive anxiety and fatigue and concentration difficulties. All these symptoms can occur in generalized anxiety disorder. The aim of this study was to assess whether fibromyalgia is associated with other diagnoses, particularly anxiety disorder. MATERIAL AND METHODS: The study includes all those receiving full disability pension on the 1st of December 2001 as ascertained by the disability register at the State Social Security Institute of Iceland. Information was obtained from the register on gender, age and diagnoses of the disability beneficiaries. Diagnoses were compared between two groups of disability beneficiaries - an index group with fibromyalgia and a comparison group without that diagnosis. There were 716 women in each group. We also compared diagnoses among the women who had fibromyalgia as primary diagnosis in the index group and among all women who had anxiety/depression as primary diagnosis. RESULTS: In the index group fibromyalgia was the single registered diagnosis in only 6.8% of cases, while 38.3% of the comparison group had a single registered diagnosis. There was a significant difference between the two groups in terms of the number of diagnoses by disease category (p<0.0001). Among individual categories of disease, the only category that showed a significant excess in the index group was mental disorders (p<0.0001). Women with fibromyalgia as a primary diagnosis were compared with women with a primary diagnosis of anxiety or depression in terms of distribution of the numbers of diagnoses per person. The distribution pattern was similar. CONCLUSIONS: The probability of having a mental disorder, especially an anxiety disorder, is significantly higher amongst women with fibromyalgia as compared to other women with full disability pension. This indicates an association between fibromyalgia and anxiety, an association which needs to be properly addressed in the treatment of this disorder.

Changes in the prevalence of disability pension in Iceland 1976-1996.

AIMS: The objectives were to determine changes in the prevalence of disability pension in Iceland and its distribution according to gender, age, and main diagnoses. METHODS: The study includes all persons receiving either full or partial disability pension in 1976 and 1996. The age-standardized risk ratio between the years 1976 and 1996 was calculated for all disability pensions and for full disability pension only. RESULTS: The prevalence of all disability pensions decreased significantly among both men and women in 1996 as compared with 1976. When the figures were disaggregated, however, theyrevealed an increased risk of full disability pension and a decreased risk of partial disability pension. Th e prevalence of full disability pension had increased in most disease categories. CONCLUSION: The decreased prevalence of disability pension in 1996 as compared with 1976 is noteworthy, as unemployment was increasing during the years immediately preceding 1996. It seems likely, however, that the decrease of partial disability pension and increase of full disability pension is a reflection of increased competition for work in the labour market as well as increased attractiveness of full disability pension due to new supplementary sickness insurance benefits linked to full disability pension.