BRITISH JOURNAL OF PSYCHIATRY (2002), 181, 129^134 Cell adhesion molecule expression in the met the DSM–IV criteria for dementia, schizophrenia or other psychotic disorders, dorsolateral prefrontal cortex and anterior a manic or hypomanic episode or a mood disorder due to a general medical condi- tion. Subjects were also excluded if they cingulate cortex in major depression in the elderly met the neuropathological criteria for any known cause of dementia (such as Alzhei- ALAN J. THOMAS, I. NICOL FERRIER, RAJESH N. KALARIA, SUE DAVIS mer’s disease, vascular dementia or demen- and JOHN T.O’BRIEN tia with Lewy bodies) or had evidence of any other neurological disorder. Control subjects were known to be capable of living independently and met the same criteria Background Neuroimaging studies The ‘vascular depression’ hypothesis pro- except that they had never suffered a have demonstrated changes in the poses that late-life depression is associated depressive episode. with vascular disease affecting the frontal- All subjects in the depression group had dorsolateral prefrontal cortex (DLPFC) subcortical circuitry, based on associations undergone extensive assessments, including and anterior cingulate cortex (ACC) in between depression and vascular disease a full history, mental state examination, major depression. (Alexopoulos et aletal, 1997) and magnetic physical examination, screening blood tests, resonance imaging studies in major depres- cognitive tests and, in some cases, computed Aims WeinvestigatedWeinvestigatedthe the expression of sion, which have shown an increase in white tomography or magnetic resonance imaging cell adhesion molecules (CAMs) in the matter lesions (WMLs) that may have a scans. All had received standard antidepres- prefrontal cortex in depression. vascular origin (O’Brien et aletal, 1996). The sant treatment regimes, with selective WMLs appear to be most strongly asso- serotonin reuptake inhibitors or tricyclic MethodMethod Immunohistochemistry to ciated with depression when they involve antidepressants singly or often in combina- localise CAMsinCAMs in post-mortemtissuepost-mortem tissue from frontal-subcortical circuits, which recipro- tion with other agents, and 11 had received cally link prefrontal areas (the dorsolateral electroconvulsive therapy. No control sub- 20 subjects with major depression and 20 prefrontal cortex (DLPFC) and the anterior ject had taken any antidepressant or anti- controls, and image analysis to quantify cingulate cortex (ACC)) to the basal ganglia psychotic medication. The case notes on their expression. (Greenwald et aletal, 1998). This is consistent all subjects were examined to see if they with positron emission tomography studies had a history of hypertension sufficient to ResultsResults Wefound significantsignificantincreases increases in depression, which have demonstrated need treatment with antihypertensive in CAMs in the grey matter of the DLPFC hypometabolism in the DLPFC (Bench medication. All subjects had had a full inthein the depression group butnobut no et aletal, 1992) and the ACC (Drevets et aletal,, post-mortem assessment (except one whose comparable differences in the ACC or 1997). This study tested whether ischaemic body was unavailable for autopsy) and the changes occur in the brain in depression in post-mortem delay was recorded. occipital cortex.Inthe white matter there the DLPFC and the ACC, by measuring was a non-significant increase in two cell adhesion molecules (CAMs). The intercellular adhesion molecule-1 in the expression of these CAMs is increased by Tissue DLPFC in the depression group but no ischaemiaischaemia in vitroinvitro (Kim, 1996) and in After death the right hemisphere was fixed human cerebral microvessels in the vicinity in 10% formalin and the brains were dis- increase ininthe the other areas or for vascular of the infarct following ischaemic stroke sected in a standard manner. To obtain tis- celladhesionmolecule-1in anyarea.Paired (Lindsberg(Lindsberg et aletal, 1996).,1996). sue blocks for analysis, tissue was selected tests showed specificity for the DLPFC in from three areas: the DLPFC (Brodmann the depression group only. areas (BA) 9 and 46), the ACC (BA 24) METHOD and the occipital cortex (BA 19 and 39) as Conclusions TheincreaseinCAM a comparison area. The DLPFC blocks expressionintheexpressionin the DLPFC suggests an Subjects were chosen by carefully selecting the coro- inflammatoryreaction andis consistent Brain tissue from 40 subjects was obtained nal slice from each subject to include BA 9 from the Neuropathology Department/ and 46 according to a standard map (Perry, with ischaemia. Newcastle Brain Tissue Bank. Permission 1993). Owing to the variation in humans, Declaration of interest None.None. had been given for post-mortem research, this may have included BA 10 in some sub- and ethical approval was granted for this jects. The ACC block was taken from BA study. Cases consisted of 20 subjects who 24 just rostral to the genu of the corpus had had depression and 20 controls. Sub- callosum or, occasionally, just including jects with depression were included if they the rostral tip of the genu. These blocks were 60 years or over at death and had were chosen to examine the areas identified suffered at least one well-documented as reduced in function in depression in the episode of DSM–IV major depression DLPFC (Bench et aletal, 1992) and ACC (American Psychiatric Association, 1994). (Drevets(Drevets et aletal, 1997). The occipital cortex Subjects were excluded if they had ever block was chosen to determine whether 129129 Downloaded from https://www.cambridge.org/core. 30 Sep 2021 at 08:21:20, subject to the Cambridge Core terms of use. THOMAS ET AL any changes in the prefrontal areas were lightly counterstained with haematoxylin structures. Interrater and intrarater reliabil- specific for these areas or occurred through- and were examined using a light micro- ity ratings were calculated (from 48 images out the brain. These blocks were embedded scope to check the quality of staining on 16 patients) for the two raters using the in paraffin wax, the duration of fixation of before proceeding to quantitative analysis. intraclass correlation coefficient and the these large blocks was recorded and they coefficient of variation, respectively. were sectioned using a sledge microtome into 10-into10-mmm sections (one per subject) on Quantitative analysis Statistical analysis large slides (36622’’’’). These slides were Analysis was conducted on one section per coded so that all analysis could be carried anatomical area per subject, based on cal- Statistical comparisons were carried out out blind to diagnosis. culations of the variability between fields using SPSS software (Version 9.0). Tests and between different immunocytochem- for normality were conducted and un- ical assays. The mean coefficient of error paired, two-way Student’s tt-tests or-testsor Immunocytochemistry for five fields (from five subjects) was Mann–Whitney tests were used, as appro- Sections were processed for immuno- 6.8% and there was very little difference priate, to compare ICAM-1 and VCAM-1 cytochemical localisation in a standard whether fields were taken from one section expression in the depression and control manner. Briefly, sections were dewaxed per subject (mean coefficient of error¼ groups. To examine whether any changes in xylene, rehydrated and microwaved in 6.6% for ten fields from five subjects) or in ICAM-1 and VCAM-1 expression 0.01% citrate buffer (pH 6.0) to optimise from two sections per subject run in differ- showed specificity for the prefrontal areas, antigen retrieval. They were immersed in ent immunocytochemistry assays (mean pairedpaired tt-tests and Wilcoxon signed rank hydrogen peroxide, blocked with an coefficient of error¼7.3% for ten fields, tests were used, as appropriate, for within- appropriate serum and incubated for 1 h five per section, from five subjects). group comparisons. Secondary analyses at room temperature with the primary Images were captured using a 661010 were conducted to examine possible con- antibody. The primary antibodies used objective lens on a Zeiss Axloplan 2 light founders. These included comparison of were a polyclonal antibody to intercellular microscope coupled to a three-chip CCD collagen IV expression in the two groups adhesion molecule-1 (ICAM-1) (R&D true-colour video camera (JVC KY F55B), and possible effects of treatment and Systems; 1:500 dilution), a polyclonal anti- producing a field size of 185 000 mmmm22 hypertension on CAM expression. Pearson body to vascular cell adhesion molecule-1 (0.185 mm(0.185mm22). For each antibody, five correlation coefficients, tt-tests or Mann– (VCAM-1) (R&D Systems; 1:800 dilution) images selected randomly were captured Whitney tests, and analysis of variance were and a monoclonal antibody to collagen from the grey matter and ten from the used, as appropriate, for these analyses. IV (Sigma; 1:500 dilution). Immuno- white matter on each section from the cytochemistry was carried out using slides DLPFC and the occipital cortex, and RESULTSRESULTS with code numbers to ensure blindedness ten from the grey matter and fifteen from and with a random order of depression the white matter in the ACC. Images were Subjects’ characteristics are given in and control cases. Slides were processed obtained randomly by the operator select- Table 1, which shows no significant differ- together for each primary antibody in ing a field by moving the stage while not ences in age,