To report a case of metachromatic leukodystrophy (MLD) being treated as Schizophrenia for over two decades.

Metachromatic leukodystrophy is a rare disease that affects one in a million. It usually presents in childhood, with history of developmental delay associated with progressive motor deficits. Manifestation in adulthood is rare, with clinical features being behavioral and mood symptoms, often leading to misdiagnosis as psychiatric conditions.

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A 44-year old woman from Western India presented with a 23-year history of progressive psychiatric symptoms. She was apparently alright till the age of 21 years, following which she started developing symptoms of impaired attention, irrelevant self talks, reduced personal care, and anger outbursts, which were attributed to psychiatric involvement. In view of associated positive maternal family history, a diagnosis of Schizophrenia was made, and she was started on psychotropic medications. However, she continued to worsen despite medications, and over the years, started developing other symptoms such as echolalia, wandering behavior, inappropriate laughter, incontinence, ultimately becoming completely dependent on her family for all her activities of daily living. Hence, diagnosis was reconsidered and neurological evaluation was done, which showed cognitive decline involving all domains with extrapyramidal features. Neuroimaging showed anterior predominant bilaterally symmetrical deep white matter signal changes. A diagnosis of adult onset metachromatic leukodystrophy was considered and Arylsulfatase A enzyme activity was done, which was found to be markedly low. Diagnosis was confirmed by whole exome sequencing, which showed homozygous ARSA gene mutation.

Adult form of Metachromatic leukodystrophy is a rare presentation, and reaching the diagnosis becomes challenging due to predominant neuropsychiatric burden. When in doubt, in patients not showing adequate clinical response to antipsychotics, organic disorders are to be considered, and detailed evaluation in the form of clinical examination and neuroimaging proves key.