Personality disorders in old age

Definition. An enduring, pervasive and inflexible pattern of inner experience and behaviour that deviates markedly from cultural expectation, with onset by adolescence or early adulthood, causing distress or impairment.

Prevalence. About 10% of community-dwelling elderly and up to one-third of older psychiatric patients. It is under-diagnosed because diagnostic criteria were validated in younger adults and depend on work and relationship domains that are irrelevant to a retired, widowed person.

Clusters and their ageing course. Cluster A (paranoid, schizoid, schizotypal) — often becomes more prominent with isolation and sensory loss. Cluster B (antisocial, borderline, histrionic, narcissistic) — impulsive traits tend to "burn out" or attenuate. Cluster C (obsessive-compulsive, avoidant, dependent) — persists or worsens; obsessive-compulsive and avoidant types are the commonest in old age.

Age-specific presentation. Expressed through illness behaviour rather than work or sexual life — treatment refusal and non-adherence, staff splitting in care homes, repeated crises, hoarding disorder, and severe self-neglect (Diogenes syndrome), querulous or demanding behaviour, and carer burnout.

Differential diagnosis — the critical point. A personality change that begins in old age is never a personality disorder. It is organic until proved otherwise — frontotemporal dementia, stroke, head injury, tumour, hypothyroidism, alcohol, or medication effect. Also exclude depression, mania and psychosis.

Management. A consistent, coordinated team approach with a single agreed care plan and clear behavioural boundaries. Psychotherapy (adapted CBT, DBT, schema-focused therapy) has evidence in older adults. Treat comorbid depression, anxiety and substance misuse. Medication only for comorbid disorder or crisis; avoid benzodiazepines. Support and supervise family carers and care-home staff.

ICD-11 dimensional model (in force since 2022, widely adopted 2023–25). The categorical subtypes have been abolished and replaced by a single diagnosis of Personality Disorder graded mild / moderate / severe, described by five trait domains — negative affectivity, detachment, dissociality, disinhibition and anankastia — plus a borderline pattern qualifier. This dimensional approach fits older adults far better than the cluster system, and DSM-5-TR retains a parallel Alternative Model (Section III). If asked for 15 marks, add: full list of the ten DSM categories with one-line descriptors; theories of trait stability versus change with ageing (maturation vs heterotypic continuity); assessment instruments (SIDP-IV, Gerontological Personality Disorder Scale, informant history); interaction of personality disorder with physical illness outcomes and rehabilitation; medico-legal aspects of self-neglect and capacity; and a worked care-plan example for Diogenes syndrome.