Asa Hammar

Haukeland University Hospital, Bergen, Hordaland, Norway

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Publications (35)74.61 Total impact

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    ABSTRACT: Major Depressive Disorder (MDD) is often associated with high levels of stress and disturbances in the hypothalamic-pituitary-adrenal (HPA) system, yielding high levels of cortisol in addition to cognitive dysfunction. The aim of the present study was to examine the relation between cortisol levels after the dexamethasone suppression test and cognitive function in recurrent unipolar MDD patients. Twenty-four patients meeting the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.) criteria for a recurrent MDD diagnosis were included in the study. The control group was matched for age, sex, and education level. Cortisol was measured in saliva collected with Salivette sampling devices. Saliva samples were collected four times during a 24-hr period over two consecutive days: at awakening, after 45 min, after 7 hr, and at 11:00 p.m. One milligram of dexamethasone was given on Day 1 at 11:00 p.m. The neuropsychological test battery consisted of standardized tests measuring cognitive functioning within verbal and visual memory, as well as executive functioning. Cortisol levels did not differ between patients and controls on Day 1. Cortisol levels in patients were higher than in controls at awakening on Day 2 (D2S1), after dexamethasone administration the previous evening. All significant correlations between cognitive measures and cortisol at D2S1 were negative, indicating that low suppression after intake of dexamethasone is related to poor cognitive functioning. Significant relations were found in three of the cognitive tests measuring verbal memory, semantic fluency, and inhibition. The present findings indicate that dysregulation of the HPA-axis is related to poor verbal memory functioning. There was no firm evidence that abnormal cortisol levels were associated with inhibition difficulties.
    PsyCh Journal. 12/2013; 2(3).
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    ABSTRACT: Introduction: Autism Spectrum Disorder (ASD) is a developmental disorder characterized by affected communication, lack of social interaction and stereotypic behavior for which no specific biological marker has been identified. We compared an ASD group and a healthy control (HC) group with regards to Gamma -Aminobutyric Acid (GABA) and glutamate levels in the left anterior cingulate cortex with non-invasive Proton Magnetic Resonance Spectroscopy (MRS) . Methods: We recruited 10 boys with autism mean age (SD) 10. 3(2.1). The ASD diagnosis was confirmed by a child and adolescent psychiatrist, using the new DSM 5 diagnostic criteria. A healthy age matched control group consisting of 10 boys aged 11.3(1.1) was recruited. All subjects were assessed with the Wechsler Abbreviated Scale of Intelligence (WASI). Exclusion criteria for both groups were braces, genetic abnormalities and prematurity <36 weeks. We used a 3T GE Signa HDxt MR scanner with a 8ch head coil acquiring a PRESS sequence, TE=35ms / TR=1500 ms and a MEGA PRESS TE=68 ms /TR=1500 ms. PRESS and MEGA PRESS data were analyzed with LCModel, both with voxel size 30 x 30 x 30 mm3. In the PRESS results we required SD<15% (Cramér-Rao lower bounds) and SD<10% for the GABA values in MEGA PRESS. Results: Using the Mann Whitney U test the relative values of GABA were higher and the relative values of glutamate were lower in the ASD group compared to the healthy control (HC) group (ASD / HC: GABA 9.25 ± 1.56/8.78 ± 0.96, Glutamate 17.62 ± 3.09 /19.08 ± 3.08), but the differences were not statistically significant. There were moreover no statistically significant differences between the two groups ASD/HC, using students t-test, in n-acetylaspartate (NAA) 7.78 ± 0.66/7,38 ±0,85, myoinositol (mI) 4.43 ± 0.63/ 4.21± 0.68, creatine(Cr)5.26 ±0.49/ 5.23 ± 0.62, choline (GPC)1.70 ± 0.30/ 1.70 ±0.20 and glutamate + glutamine (Glx)12.65 ± 12.65 ±2.2/ 11.41 ± 2.14). Discussion: Our preliminary results from this ongoing study of boys with ASD do not support an excitatory/inhibitory imbalance hypothesis where ASD symptoms are explained by overactivity of the glutamate system due to lack of GABA inhibition. However, previous studies using the same technique have shown lower concentration of GABA in ASD subjects compared to HC in specific areas of the brain, with no group differences in other areas of the brain. The sample size in our study is small, and further inclusion of subjects may influence our findings. Conclusion: We found relatively lower glutamate and higher GABA concentrations in the left anterior cingulate cortex in the ASD group compared with the healthy control group, although the difference was small and statistically non-reliable.
    Neuroscience 2013, San Diego; 11/2013
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    ABSTRACT: Intracranial arachnoid cysts have been shown to yield cognitive impairment over a range of basic mental functions, and these functions normalize after surgical cyst decompression. We wanted to investigate whether such cysts may also impair executive cognitive functions, and whether surgical cyst decompression leads to an improvement. This study included 22 patients with arachnoid cysts and 13 control patients scheduled for low back surgery. All subjects were tested with Delis-Kaplan Executive Function System (D-KEFS) tests, assessing executive function 1 day before surgery and a minimum of 3 months after surgery. The data were analyzed according to scaled score computations based on raw scores provided by D-KEFS, adjusted for age, gender, and educational norms. Preoperatively, the patients with cysts group performed worse than the control group in verbal knowledge, mental flexibility, inhibitory capacity, problem solving, and planning skills. Postoperatively, the patients with cysts group significantly improved performance and were no longer different from the control group in the following subtests: inhibition, inhibition/switching, letter fluency, category switching, and total switching accuracy. The patients with cysts group also significantly improved performance in color naming, category fluency, and in the Tower test, but nevertheless remained impaired at follow-up compared with the control group. The control group did not show a similar improvement, except for the Tower test. Cyst size or postoperative volume reduction did not correlate with cognitive performance or postoperative improvement. Patients with left-sided temporal cysts performed poorer than patients with right-sided cysts on a complex verbal task demanding mental flexibility. Arachnoid cysts seem to impair not only basic cognition, but also executive functions. Most of this impairment appears to be reversible after surgical cyst decompression. These results may have implications for future preoperative considerations for patients with intracranial arachnoid cysts.
    Journal of Neurodevelopmental Disorders 08/2013; 5(1):21. · 3.45 Impact Factor
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    ABSTRACT: BACKGROUND: The literature on the neuropsychological profiles in Bipolar disorder (BD) depression is sparse. The aims of the study were to assess the neurocognitive profiles in treatment-resistant, acutely admitted BD depression inpatients, to compare the neurocognitive functioning in patients with BD I and II, and to identify the demographic and clinical illness characteristics associated with cognitive functioning. METHODS: Acutely admitted BD I (n = 19) and BD II (n = 32) inpatients who fulfilled the DSM-IV-TR criteria for a major depressive episode were tested with the MATRICS Consensus Cognitive Battery (MCCB), the Wechsler Abbreviated Scale of Intelligence, the National Adult Reading Test, and a battery of clinical measures. RESULTS: Neurocognitive impairments were evident in the BD I and BD II depression inpatients within all MCCB domains. The numerical scores on all MCCB-measures were lower in the BD I group than in the BD II group, with a significant difference on one of the measures, category fluency. 68.4% of the BD I patients had clinically significant impairment (>1.5 SD below normal mean) in two or more domains compared to 37.5% of the BD II patients (p = 0.045). A significant reduction in IQ from the premorbid to the current level was seen in BD I but not BD II patients. Higher age was associated with greater neurocognitive deficits compared to age-adjusted published norms. CONCLUSIONS: A high proportion of patients with therapy-resistant BD I or II depression exhibited global neurocognitive impairments with clinically significant severity. The cognitive impairments were more common in BD I compared to BD II patients, particularly processing speed. These findings suggest that clinicians should be aware of the severe neurocognitive dysfunction in treatment-resistant bipolar depression, particularly in BD I.Trial registration:
    BMC Psychiatry 04/2013; 13(1):105. · 2.23 Impact Factor
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    Mari Strand, Mike W Oram, Asa Hammar
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    ABSTRACT: Although there is considerable knowledge of the cognitive and perceptual deficits associated with the acute phases of major depressive disorder (MDD), the processes involved in remission and relapse are still being evaluated. In the present study emotional information processing in remission was investigated. A Stroop paradigm was used to compare responses from a group of remitted or partially remitted MDD patients with a matched control group. The stimuli consisted of lexical and visual facial stimuli, with one word (positive/negative) superimposed on a face (happy/sad), presented in the same trial, and being congruent or incongruent. The task was to identify the emotional content of either the face (ignoring the word), or vice versa. The results showed that both patients and controls had the same interference patterns when the target was defined by the word, and that when the target was defined by the facial expression, reaction times were faster for both groups. However, patients showed a reduced positive bias, possibly indicating dissociation between patients and control groups in terms of attention to complex emotional information. Future studies testing the sensitivity of the Emotional Stroop test in the investigation of attention to complex emotional information is needed. Clinical implications are discussed.
    Applied Neuropsychology 04/2013; 20(2):110-9. · 1.32 Impact Factor
  • Asa Hammar, Marit Schmid
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    ABSTRACT: The aim of the present study was to investigate delayed recall, recognition, and visual-spatial memory among subjects (N = 24) with major depressive disorder (MDD) following 9 months of recovery from acute depression. Visual-spatial memory assessment was conducted using the Rey Complex Figure Test. In the acute phase, the MDD subjects performed significantly worse compared with control subjects in delayed recall and recognition. Following 9 months of recovery, there were no longer differences between groups. The MDD group made a significant improvement in terms of depressive symptoms and performed better in recall and recognition. The results suggest that depression and memory performance are linked.
    Applied Neuropsychology 02/2013; · 1.32 Impact Factor
  • Marit Schmid, Asa Hammar
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    ABSTRACT: Introduction. Executive Functions (EF) has been documented to be impaired in patients with recurrent Major Depressive Disorder (MDD) in several studies. Longitudinal studies have suggested that these impairments may be a result of several episodes of depression or they may represent stable traits in this patient group. However, few studies have addressed these issues and investigated cognitive functioning with a particular focus on EF in patients who experience MDD for the first time. Methods. In the present study, the executive functions of inhibition, verbal fluency, mental flexibility, and planning and problem solving were investigated in a group of patients diagnosed with first episode MDD. Thirty patients and 30 control subjects were included in the study. Results. The patient group performed significantly more poorly in the cognitive functions of inhibition and semantic fluency. In addition, the patient group showed a reduced speed of mental processing on some of the measures. However, the results showed that reduced processing speed alone could not account for the poor performance in inhibition and semantic fluency. There were no differences between the two groups in the other measures of EF, indicating that functioning of mental flexibility, phonemic fluency, planning, and problem solving was intact in the patient group. Conclusions. The results show that impaired inhibition and semantic fluency are present early in the course of MDD. The present findings indicate that poor inhibition and performance in semantic fluency may represent stable traits in MDD, independent of symptom severity and the number of depressive episodes.
    Cognitive Neuropsychiatry 01/2013; · 1.68 Impact Factor
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    ABSTRACT: BACKGROUND: Patients with panic disorder (PD) are known to report impaired sleep quality and symptoms of insomnia. PD is an anxiety disorder characterised by deficient physiological regulation as measured by heart rate variability (HRV), and reduced HRV, PD and insomnia have all been related to impaired inhibitory ability. The present study aimed to investigate the interrelationships between subjectively reported sleep impairment, cognitive inhibition and vagally mediated HRV in a sample characterised by variability on measures of all these constructs. METHODS: Thirty-six patients with PD with or without agoraphobia were included. Cognitive inhibition was assessed with the Color-Word Interference Test from the Delis-Kaplan Executive Function System (D-KEFS), HRV was measured using high frequency (HF) power (ms(2)), and subjectively reported sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI). RESULTS: Cognitive inhibition was related to both Sleep latency and Sleep disturbances, whereas HRV was only related to Sleep disturbances. These relationships were significant also after controlling for depression. LIMITATIONS: Correlational design. CONCLUSION: Cognitive inhibition is related to key insomnia symptoms: sleep initiation and sleep maintenance. The data supports the psychobiological inhibition model of insomnia, and extends previous findings. Possible clinical implications of these findings are discussed.
    Journal of affective disorders 01/2013; · 3.76 Impact Factor
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    Marit Schmid, Asa Hammar
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    ABSTRACT: The present study investigated the Executive Functions (EF) of inhibition, mental flexibility and phonemic and semantic fluency in a 1-year follow-up assessment of patients diagnosed with first episode Major Depressive Disorder (MDD). In the acute phase, the patient group performed significantly poorer compared to the control group (CG) in inhibition and semantic fluency. The present study pursued these findings from the acute phase to see if the impairment seen in inhibition and semantic fluency in the acute phase normalized or persisted in the follow-up assessment. In addition, the present study investigated the association between poor inhibition and semantic fluency performance and the experience of relapse during the 1-year period. Twenty eight patients and 28 individually matched control subjects were included. EF was reassessed using three tests from the Delis Kaplan Executive Function System (D-KEFS). Results: There was a significant decrease in depression severity score from the acute phase, showing that most of the patients were in remission in the follow-up assessment. Results showed a sustained impairment in inhibition and semantic fluency in the patient group. However, the performance in inhibition was more severe when an additional requirement of mental flexibility was included. There were no group differences in the other EF functions measured. Further, patients with a relapse in the course of 1 year performed significantly poorer in inhibition/switching at inclusion compared to patients that did not relapse and the CG. This relationship was not found for semantic fluency. Poor performance in inhibition and semantic fluency are prolonged despite symptom reduction in patients with a first episode of MDD. Moreover, although based on a small sample of patients, the present study showed that there may be a relationship between impaired ability in the EF of inhibition/switching and vulnerability for the experience of relapse.
    Frontiers in Psychology 01/2013; 4:633. · 2.80 Impact Factor
  • Journal of Affective Disorders. 01/2013;
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    Asa Hammar, Guro Ardal
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    ABSTRACT: The aim of the present study was to investigate verbal memory performance in a group of patients with remitted and partial remitted major depressive disorder. Thirty-one patients and 31 healthy matched controls were included in the study. Results from the California Verbal Learning Test show intact verbal memory performance in the patient group regarding learning, recall and recognition. However, patients had significantly poorer performance compared to healthy controls in immediate recall of the first trial in the verbal memory test. In conclusion, the patient group showed intact memory performance, when material is presented more than once. These findings indicate that memory performance in MDD patients with partial remission and remission benefit from repetition of material.
    Frontiers in Psychology 01/2013; 4:652. · 2.80 Impact Factor
  • Guro Ardal, Anders Lund, Asa Hammar
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    ABSTRACT: Årdal G, Lund A, Hammar Å. Health-related quality of life in recurrent major depressive disorder-A 10-year follow-up study. Nord J Psychiatry 2012;Early online:1-5. Background: Major depressive disorder strongly affects health-related quality of life (HRQOL). Few studies have followed patients suffering recurrent major depressive disorder (rMDD) and paid attention to HRQOL in remitted state. Aim: The aim of the present study was to assess HRQOL in a 10-year longitudinal perspective in patients suffering rMDD, and comparable healthy control subjects. Results: The results show significant lowered HRQOL in depressed patients on all measured domains in the acute phase of illness. Conclusions: Although HRQOL in the depressed patient group significantly improved on most measures between the two assessments, the patient group still reported a significant lowered HRQOL compared with matched controls at the 10-year follow-up assessment. More research should focus on HRQOL after a depressive episode.
    Nordic journal of psychiatry 12/2012; · 0.99 Impact Factor
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    ABSTRACT: Hammar, Å., Kildal, A. B. & Schmid, M. (2012). Information processing in patients with first episode major depression. Scandinavian Journal of Psychology 53, 445-449. Few studies have investigated cognitive functioning in a group of patients experiencing a first episode of depression. The aim of this study was to investigate how patients diagnosed with a first episode of depression perform in effortful and non-effortful information processing compared to healthy controls. An experimental paradigm based on a visual search test was applied. Thirty-one patients and thirty-one healthy controls were included in the study. All patients experienced a severe level of symptom load at the time of testing. Results showed no significant differences between groups under any of the conditions. Findings in the present study indicate that patients with a first episode of depression perform equally to healthy controls in tasks requiring visual attention in both effortful and non-effortful information processing.
    Scandinavian Journal of Psychology 12/2012; 53(6):445-9. · 1.29 Impact Factor
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    ABSTRACT: Heart rate variability (HRV) is reduced in patients who suffer from panic disorder (PD). Reduced HRV is related to hypoactivity in the prefrontal cortex (PFC), which negatively affects executive functioning. The present study assessed the relationships between vagally mediated HRV at baseline and measures of executive functioning in 36 patients with PD. Associations between these physiological and cognitive measures and panic-related variables were also investigated. HRV was measured using HF-power (ms(2)), and executive functions were assessed with the Wisconsin Card Sorting Test (WCST) and the Color-Word Interference Test (CWIT) from the Delis-Kaplan Executive Function System (D-KEFS). Panic-related variables comprised panic frequency, panic-related distress, and duration of PD. Performance on the neuropsychological measures correlated significantly with HRV. Both panic-related distress and duration of PD were inversely related with measures of HRV and cognitive inhibition. The current findings support the purported relationship between HRV and executive functions involving the PFC.
    International journal of psychophysiology: official journal of the International Organization of Psychophysiology 10/2012; · 3.05 Impact Factor
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    ABSTRACT: Introduction: Depression is associated with cognitive deficits, social withdrawal and high risk of relapse. Several factors have been proposed as pertaining to increasing the risk of relapse, including a bias in emotional information processing. This study was carried out to examine the relationships between major depressive disorder (MDD), level of depressive symptoms and bias in emotional effortful information processing. Method: Nineteen patients diagnosed with recurrent MDD and 19 matched controls were tested with an experimental visual face-in-the-crowd paradigm including sad, happy and neutral information. The patients were tested on average 9 months after hospitalization. At testing, the patient group showed an overall decrease in depression severity symptom load as measured on the Hamilton Depression Rating Scale (HDRS), but with variable symptom load. Results: Reaction time (RT) did not vary between patients and controls in the visual face-in-the-crowd task or on a measure of psychomotor speed. In the patient group, symptom load was related to longer RTs when negative targets were shown against positive distractors. The results revealed a specific bias in response to negative emotional information. Conclusions: Symptom load in the patient group is related to a negative bias in emotional information processing that cannot be explained by psychomotor retardation.
    Nordic journal of psychiatry 08/2012; · 0.99 Impact Factor
  • Asa Hammar, Guro Ardal
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    ABSTRACT: The aim of the present study was to longitudinally investigate effortful cognitive functioning in a group of patients diagnosed with major depressive disorder (MDD) in a 10-year follow-up period. Results at inclusion in the acute phase of MDD showed impaired effortful processing and that this impairment prevailed at a 6-month follow-up, despite significant symptom reduction. Non-effortful processing was normal as compared to healthy controls. Sixteen patients along with 16 healthy controls were included in the 10-year follow-up. They all participated in the original study and were matched for age and educational length. The mean symptom load at the time of testing at the 10-year follow-up indicated that the patients as a group were in remission. All participants were examined with a visual search paradigm, with demands for effortful and non-effortful processing. Results showed that the patient group had normalized their performance for effortful information processing and no longer differed significantly from the healthy controls at the 10-year follow-up, and the lack of difference between the groups for non-effortful processing remained the same. These results indicate that short-term effortful cognitive impairments normalize over the course of long-term recovery that goes together with clinical improvement and remission.
    Psychiatry Research 03/2012; · 2.68 Impact Factor
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    ABSTRACT: In the present study, verbal and visual memory functioning in a group of recurrent major depressive disorder patients were investigated. The study included 48 participants: 24 patients and 24 control subjects. Verbal and visual memory were investigated using the California Verbal Learning Test and the Rey Complex Figure Test. The results show that the depressed patients performed significantly worse compared with the controls on the very first trial in the verbal memory test. On all other conditions, the patients showed intact verbal memory, while visual memory was impaired. It is important to highlight the intact verbal memory performance in the acute phase of illness to detect cognitive strengths in this patient group.
    Applied Neuropsychology 07/2011; 18(3):191-6. · 1.32 Impact Factor
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    ABSTRACT: Several studies have demonstrated impaired performance in inhibition and semantic fluency in the acute phase of illness in patients with recurrent major depression. However, few studies have investigated these functions longitudinally, focusing on how these impairments relate to symptoms over time. The present longitudinal study investigated whether the specific impairment in inhibition and semantic fluency seen in the acute phase of Major Depressive Disorder (MDD) was prolonged or normalized with symptom reduction in a 9-month follow-up. Twenty recurrent major depressive patients and 19 control subjects were included in the study. Inhibition and semantic fluency were investigated using tests from the Delis-Kaplan Executive Function System. The results show that the patient group still had significantly lower scores in inhibition and semantic fluency compared with the control group despite significant symptom reduction. Further, the results show that impaired inhibition in the acute phase was strongly correlated with impaired inhibition in the follow-up, suggesting that the inability to inhibit may represent a trait marker in recurrent MDD.
    Archives of Clinical Neuropsychology 06/2011; 26(7):677-86. · 2.00 Impact Factor
  • Guro Årdal, Åsa Hammar
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    ABSTRACT: Even though many studies demonstrate cognitive impairment in the acute phase of depression and several studies indicate that this impairment might be long lasting despite symptom reduction and recovery, there is a lack of longitudinal studies on this field with considerable follow-up length. The aim of this study was to investigate whether the impairment observed in cognitive inhibition in the acute phase of depression is reversible or irreversible in a 10-year follow-up assessment. A longitudinal study of 38 individuals, 19 with recurrent unipolar depression and 19 healthy controls matched for gender, age, and education were included in the study. Cognitive inhibition was investigated using the Stroop test at three different occasions: acute phase, short-term (6 months), and long-term (10 years) follow-up. The results show that recurrent major depressive disorder patients have a long-lasting impairment in inhibition as measured by the Stroop test in 10-year follow-up. Further there is high consistency in inner group performance suggesting that severe impairment in the acute phase of illness is associated with severe impairment 10 years later despite recovery in the patient group. The results show that impairment in cognitive inhibition is long lasting when present in the acute phase of recurrent depression. Impaired cognitive inhibition might be an irreversible vulnerability marker for recurrent depression.
    Psychology and psychotherapy. 06/2011; 84(2):141-50.
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    ABSTRACT: It is widely accepted that depression is associated with deficits in a range of cognitive domains. However, there is no consensus regarding the neuropsychological profile in depression. The aim of the present report is to test the cognitive effort hypothesis as a possible framework for understanding the observed cognitive impairment in major depressive disorder (MDD), using the Delis Kaplan Executive Function system (D-KEFS). Twenty-four patients with recurrent MDD, in the acute phase of illness, were compared with a healthy control group. We expected that the patient group would show impairment on tests that measure higher-level effortful cognitive processing, whereas basic cognitive skills would be equal to the control group. There were no differences between the two groups on measures of basic cognitive skills, except for Colour Naming. Furthermore, MDD patients performed significantly worse than the control group on three out of seven of the cognitively effortful measures; namely Inhibition, Inhibition/Switching and Category Fluency. We could not find consistent support for the cognitive effort hypothesis in the present study. However, the results indicate that depressed patients have a specific impairment within the Executive Function domain affecting Inhibition, Inhibition/Switching and Category Fluency.
    Nordic journal of psychiatry 02/2011; 65(1):74-80. · 0.99 Impact Factor

Publication Stats

327 Citations
74.61 Total Impact Points


  • 2013
    • Haukeland University Hospital
      Bergen, Hordaland, Norway
  • 1997–2012
    • University of Bergen
      • • Department of Biological and Medical Psychology
      • • Department of Clinical Medicine
      Bergen, Hordaland Fylke, Norway