Our Staff
Eleftheria Tsavoussis, PMHCNS-BC
Owner, CEO & Psychiatric Clinical Nurse Specialist
Eleftheria Tsavoussis is a seasoned Psychiatric Clinical Nurse Specialist and Adult Nurse Practitioner with over 25 years of experience across multiple healthcare settings. She offers psychopharmacologic treatment for adult clients with a focus on resistant depression, anxiety and panic disorders, ADHD testing and treatment, bipolar disorder, substance abuse and women’s issues.
Click here to learn more
Before joining Waltham Behavioral Health, LLC, Ms. Tsavoussis was a Psychiatric Clinical Nurse Specialist in private practice in Newton, at Greater Lowell Psychiatric Associates, Nova Psychiatric, Neurobehavioral Associates, and Neponset Health Center. Ms. Tsavoussis has been double-boarded in as a primary care Nurse Practitioner, and a Psychiatric Clinical Nurse Specialist and divided her time between primary care and psychopharmacology at Neponset Health Center until 2008. Prior to that, Ms. Tsavoussis was owner and CEO of Bayside Nursing Placement. Eleftheria Tsavoussis received her Post-Master’s Certification as Psychiatric Clinical Nurse Specialist from Boston College and a Master of Science from Simmons College. She received her bachelor’s degree in nursing from Boston College. She currently is an Adjunct Assistant Professor at UMass Lowell and has held teaching positions with Boston College and Simmons College. Ms. Tsavaoussis is a certified Psychiatric Clinical Nurse Specialist by the American Nurse Credentialing Center. She is a member of the Massachusetts Coalition of Nurse Practitioners and serves on the Massachusetts Action Coalition working to remove restrictions that limit patients’ access to high-quality, cost effective health care across a variety of specialties including primary care, psychiatric and mental health care, and pediatrics where patient care needs exceed physician supply. Ms. Tsavoussis was a contributing author to the MA Action Coalition Report: The Advanced Practice Nurse in Massachusetts.
Suzanne Brennan-Nathan, LICSW, C.G.P.
Clinical Social Worker
Suzanne Brennan-Nathan’s areas of specialty include: trauma, sexual abuse, depression, group psychotherapy, eating disorders and adult children of alcoholics and dysfunctional families. She has over 30 years of experience in counseling and social work.
Click here to learn more
In addition to her work with Waltham Behavioral Health, LLC, Ms. Brennan-Nathan is a private practice therapist and Director of Trauma Services, Director of Training and Clinical Director at Sameen Associates, Inc. Prior to joining Waltham Behavioral Health, LLC, she was the Clinical Director of Lifecycle Counseling Center and the Director of the Cambridge Hospital Crisis Team. Suzanne Brennan-Nathan received a Master of Social Work from Smith College. Ms. Brennan Lambert has held teaching positions with Boston University, Simmons College, Smith College and Boston College. Ms. Lambert is a member of the National Association of Social Workers, American Group Psychotherapy Association, New England Group Psychotherapy Association, and the New England Society for the Treatment of Trauma.
Chris Shaw, PMHNP-BC
Psychiatric Mental Health Nurse Practitioner
Christopher Shaw offers psychopharmacology services for adolescent and adult patients. He specializes in treating patients with dual diagnoses of mental health and addictions. In addition to his work with Waltham Behavioral Health, LLC, Mr. Shaw is a nurse practitioner Addictions Consult Team Leader at Massachusetts General Hospital.
Click here to learn more
Prior to joining Waltham Behavioral Health, LLC, he was a nurse practitioner in multiple departments at Massachusetts General Hospital and a nurse manager at Pine Street Inn. He was also a nurse practitioner at the Barbara Mcinnis House Respite, Boston Health Care for the Homeless. Christopher Shaw received a Post Master’sCertificate in Psychiatric Nursing from the University of Massachusetts, Lowell and a Masters in Nursing from the University of Massachusetts Boston. Mr. Shaw is an active member of the International Nurses Society of Addictions, and present board member and past president of the Association of Nurses in AIDS Care. In addition, he is the cofounder and Board Secretary of NPO Sibusiso.
Christine Aposhian, Ed.D, M.Ed.
Psychologist
Christine Aposhian has over 30 years of experience in the mental health field with a special interest in diagnosing and treating bipolar spectrum disorders. She especially enjoys incorporating the arts into therapy. Prior to joining Waltham Behavioral Health, Ms. Aposhian was a psychologist at Greater Lowell Psychiatric Associates, at The Psychological Center in Lawrence, and the North Essex Mental Health Center.
Click here to learn more
Christine Aposhian received a Doctor of Education in Counseling Psychology from Boston University and a Master of Education in Counseling from Boston University.
Susan Korber, PMHCNS-BC
Psychiatric Mental Health Nurse Practitioner
Susan Korber, PMHCNS-BC Sue Korber is an experienced clinical nurse specialist treating children, adolescents and adults across the lifespan. She offers psychopharmacologic assessment and treatment for these patient populations and has been working in this arena for thirty-one years. She has extensive experience working with affective disorders such as Depression and Bipolar disorder, ADHD, PTSD, Autism Spectrum Disorders, Disruptive Mood Dysregulation disorder, Substance Use disorders and has special expertise in Tourette’s Syndrome and other movement disorders.
Click here to learn more
Before joining Waltham Behavioral Health Ms. Korber gained wide-ranging expertise in various roles. Susan has worked as a Clinical Nurse Specialist at Sameem Associates in Newton, MA and at Nova Psychiatric and Neuro Behavioral Associates in the Greater Boston metropolitan area. Her resume also includes work in the Outpatient Department at Tufts New England Medical Center as well as a tenure on the Inpatient Psychosomatic Unit at Boston’s Children’s Hospital. Additionally, for the past sixteen years, Susan has worked at Italian Home for Children in acute residential, long-term residential and outpatient-care settings providing children, adults and families medication evaluation and treatment assessment. Susan received her Bachelor of Science in Nursing from Simmons College and her Master of Science in Psychiatric Nursing from Boston University. She is Board Certified through the American Nurses Credentialing Center.
Linda Simon LICSW
Clinical Social Worker
Linda Simon LICSW Linda has more than thirty years’ experience treating children, adolescents and adults in individual, couples and family therapy. She focuses on the needs of each client through the integration of cognitive-behavioral therapy (CBT), psychodynamic psychotherapy and family systems modalities.
Marylouise Demick, PMHNP-BC
Psychiatric Mental Health Nurse Practitioner
Marylouise Demick, PMHNP-BC, has psychiatric experience providing psychotherapy and psychopharmacology treating patients in both inpatient, partial programs and adult outpatient clinical settings. She is currently a Psychiatric Nurse Practitioner at McLean Hospital and serves as adjunct faculty at Boston College. While working as a staff nurse at Brigham and Women’s Hospital, Marylouise’s primary interests were parenting education and family intervention in areas of perinatal loss, In Vitro Fertilization, postpartum depression and parenting. Before working at Waltham Behavioral Health, Marylouise continued building her expertise by completing a postgraduate psychiatric residency at the Boston VA concentrating on depression, anxiety, mood disorders, trauma, addictions, PTSD and narrative therapy.
Margaret (Meg) van Bael LICSW
Clinical Social Worker
Margaret (Meg) van Bael has worked in the mental health field for thirty years with adults of all ages. Her areas of specialization include unipolar and bipolar depression, PTSD and other anxiety disorders, adult children of alcoholics, dual diagnosis (substance use disorder and mental illness), chronic illness and stress, life role transitions and issues of grief and loss. Since she believes that there is no such thing as “One size fits all” when it comes to mental health treatment, her style is eclectic, incorporating supportive interpersonal work, CBT, mindfulness and other modalities. During her academic training, she worked at the EN Rogers Memorial Veterans’ Hospital before graduating Summa cum Laude from the Salem State Graduate School of Social Work. Prior to joining Waltham Behavioral Health, she worked for McLean Hospital, Program of All-inclusive Care for the Elderly (PACE) and Jewish Family and Children’s Service. She is a member of the Private Practice Shared Interest Group of the Massachusetts National Association of Social Workers.
Karen Kronenberg LICSW
Licensed Independent Clinical Social Worker
Karen Kronenberg is a (LICSW) who specializes in helping adults who are facing issues with depression, anxiety, grief and loss, relationship problems or other mental-health concerns. Prior to joining Waltham Behavioral Health, she served as a hospice social worker, ran a dual-diagnosis group at a Partial Hospital Program, and as a psychotherapist at different mental-health agencies prior to WBH. Mental Health Association. Karen specializes in using a combination of psychodynamic therapy, cognitive-behavioral therapy (CBT), dialectical behavioral therapy (DBT), and Emotionally Focused Therapy (EFT) in a warm, supportive environment while challenging clients as appropriate. She holds a B.A. in Human Services from the University of Massachusetts/Boston and an MSW from Simmons University’s Graduate School of Social Work.
